Four Hours of Tide experience by Evelina Phemister

Thoughts on Entrada Rag from the think on paper series of promotions from Moab.

Four Hours of Tide Experience Paper Line

E NTRADA RAG

Paper Company

Brand

LEGION PAPER MOAB

Four Hours of Tide Experience

Four Hours of Tide Experience Paper Line

E NTRADA RAG

Paper Company

Brand

LEGION PAPER MOAB

Academy of Art University _ San Francisco, CA

6 COPYRIGHT

This book is devoted to people who walked on the ocean bottom during the massive negative tide on November 15, 2009 and all scientists and rangers who educated people to appreciate and save the ocean life.

DEDICATION 7

8 CONTENT

CONTENT

10 _ Legion Paper/Moab/Entrada 12 _ Concept 14 _ Tide Characteristics 16 _ Tide Definition 18 _ Tide Hystory 20 _ The Web of Life 24 _ Meet the Starfish 28 _ Meet the Crab 32 _ Meet the Sea Anemone 38 _ Look at the Mussel 42 _ Admire the Seaweed 46 _ Production Notes 48 _ Moab Products/Colophon

LEGION PAPER / MOAB / ENTRADA

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LEGION PAPER / MOAB / ENTRADA

LEGION PAPER } North Americaâ&#x20AC;&#x2122;s premier distributor of fine art papers and museum board sourced from mills around the world, is committed to developing innovative products, which } empower visual thinkers to share their inspiration. MOAB Created in Moab, UT surrounded by the endless red rock wonders of Arches and Canyonlands National Parks, the Colorado River, and the LaSal Mountains, the Moab line of archival, digital imaging papers continues to rely on that inspiration to design premium solutions for digital photographers and artists.

Double-sided Sheets and Rolls Entrada Rag Bright 190 Entrada Rag Bright 300 Entrada Rag Natural 190 Entrada Rag Natural 300 Single-sided Rolls Entrada Rag Bright 290 Entrada Rag Natural 290

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CONCEPT

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NEW EXPERIENCE

CONCEPT

Unforgettable experience visiting Half Moon Bay during the massive negative tide and observing the ocean bottom life people rarely have chance to see. EBB TIDE Massive Negative Tide SUNDAY _ November 15, 2009 Half Moon Bay, CA These very low tides only happen a few times per year, and usually at night or during the week. This is a rare daytime weekend chance to see tons of critters that are rarely visible. Mussels, sea stars, eels, clams, crabs, and many other critters become trapped in the tide pools for a few hours. The reef is walkable starting shortly after 1PM, lowest tide is 3PM, the reef remains walkable until about 5PM. Please do not touch animals nor disturb sealife in any way. Watch your step and only walk on bare rock. Take only pictures,leave nothing behind.

14 TIDE CHARACTERISTICS

NOVEMBER 15, 2009

1:00 PM

CHARACTERISTICS

Higher High Water

Lower High Water

Lower Low Water

Higher Low Water

TIDE DEFINITION

NOVEMBER 15, 2009

MARINE ECOSYSTEMS AND THEIR DIVERSITY

Shoreline Communities

Experience N 1 Common name

E B B TI DE

Range Variations SPRING NEAPS

Tides are the rise and fall of ocean levels caused by the combined effects of the rotation of the Earth and the gravitational forces exerted by the Moon and the Sun. The tides occur with a period of approximately 12 and a half hours and are influenced by the shape of the near-shore bottom. Neap Tide Earth

Moon

Spring Tide

Spring Tide Sun

Most coastal areas experience two daily high (and two low) tides. This is because at the point right “under” the Moon (the sub-lunar point), the water is at its closest to the Moon, so it experiences stronger gravity and rises. On the opposite side of the Earth (the antipodal point), the water is at its farthest from the moon, so it is pulled less; at this point the Earth moves more toward the Moon than the water does—causing that water to “rise” (relative to the Earth) as well. In between the sub-lunar and antipodal points, the force on the water is diagonal or transverse to the sub-lunar/antipodal axis (and always towards that axis), resulting in low tide. CHARACTERISTICS Tides are most commonly semidiurnal (two high waters and two low waters each day), or diurnal (one tidal cycle per day). The two high waters on a given day are typically not the same height (the daily inequality); these are the higher high water and the lower high water in tide

tables. Similarly, the two low waters each day are the higher low water and the lower low water. The daily inequality is not consistent and is generally small when the Moon is over the equator. Tide changes proceed via the following stages: 1. Sea level rises over several hours, covering the intertidal zone; flood tide. 2. The water rises to its highest level, reaching high tide. 3. Sea level falls over several hours, revealing the intertidal zone; ebb tide. 4. The water stops falling, reaching low tide. HISTORY OF TIDAL PHYSICS Tidal physics was important in the early development of heliocentrism and celestial mechanics, with the existence of two daily tides being explained by the moon’s gravity. More precisely the daily tides were explained by universal gravitation involving the interaction of the moon’s gravity and the sun’s gravity to cause the variation of tides. An early explanation of tides was given by Galileo Galilei in his 1632 Dialogue Concerning the Two Chief World Systems, whose working title was Dialogue on the Tides. However, the resulting theory was incorrect - he attributed the tides to water sloshing due to the Earth’s movement around the Sun, hoping to provide mechanical proof of the Earth’s movement - and the value of the theory is disputed, as discussed there. At the same time Johannes Kepler correctly suggested that the Moon caused the tides, based upon ancient observation and correlations, which was rejected by Galileo. It was originally mentioned in Ptolemy’s Tetrabiblos as being derived from ancient observation. AAAIsaac Newton (1642–1727) was the first person to explain tides scientifically. His explanation of the tides was published in 1686, in the second volume of the Principia. Isaac Newton laid the foundations of scientific tidal studies with his mathematical explanation of tide-generating forces in the Philosophiae Naturalis Principia Mathematica. Newton first applied the theory of universal gravitation to account for the tides as due to the lunar and solar attractions, offering an initial theory of the tide-generating force. Newton and others before Pierre-Simon Laplace worked with an equilibrium theory, largely concerned with an approximation that describes the tides that would occur in a non-inertial ocean evenly covering the whole Earth.The tidegenerating force is still relevant to tidal theory, but as an intermediate quantity rather than as a final result; theory has to consider also the Earth’s dynamic tidal response to the force, a response that is influenced by bathymetry, Earth’s rotation, and other factors. In 1740, the Académie Royale des Sciences in Paris offered a prize for the best theoretical essay on tides.

1:20 PM

RANGE VARIATION: SPRINGS AND NEAPS The semidiurnal tidal range (the difference in height between high and low waters over about a half day) varies in a two-week cycle. Around new and full moon when the Sun, Moon and Earth form a line (a condition known as syzygy 1 ), the tidal force due to the Sun reinforces that due to the Moon. The tide’s range is then at its maximum: this is called the spring tide, or just springs. It is not named after the season but, like that word, derives from an earlier meaning of “jump, burst forth, rise” as in a natural spring. When the Moon is at first quarter or third quarter, the Sun and Moon are separated by 90° when viewed from the Earth, and the solar gravitational force partially cancels the Moon’s. these points in the lunar cycle, the tide’s range is at its minimum: this is called the neap tide, or neaps (a word of uncertain origin). Spring tides result in high waters that are higher than average, low waters that are lower than average, slack water 2 time 2 that is shorter than average and stronger tidal currents than average. Neaps result in less extreme tidal conditions. There is about a seven day interval between springs and neaps.The changing distance separating the Moon and Earth also affects tide heights. When the Moon is at perigee the range increases, and when it is at apogee the range shrinks. Every 7½ lunations (the full cycle from full moon to new to full), perigee coincides with either a new or full moon causing perigean spring tides with the largest tidal range. If a storm happens to be moving onshore at this time, the consequences (property damage, etc.) can be especially severe.

TIDE DEFINITION

1 In broadest terms, syzygy is a kind of unity, especially through coordination or alignment, most commonly used in the astronomical

BATHYMETRY The shape of the shoreline and the ocean floor change the way that tides propagate, so there is no simple, general rule for predicting the time of high water from the Moon’s position in the sky. Coastal characteristics such as underwater bathymetry and coastline shape mean that individual location characteristics affect tide forecasting; actual high water time and height may differ from model predictions due to the coastal morphology’s effects on tidal flow. However, for a given location the relationship between lunar altitude and the time of high or low tide (the lunitidal interval) is relatively constant and predictable, as is the time of high or low tide relative to other points on the same coast. Land masses and ocean basins act as barriers against water moving freely around the globe, and their varied shapes and sizes affect the size of tidal frequencies. As a result, tidal patterns vary. For example, in the U.S., the East coast has predominantly semi-diurnal tides, as do Europe’s Atlantic coasts, while the West coast predominantly has mixed tides.

and/or astrological sense. Syzygy is derived from the Late Latin syzygia, “conjunction,” from the Greek (syzygos). Syzygial, adjective of syzygy, describes the alignment of three or more celestial bodies in the same gravitational system along a line. 2

Slack water, or slack tide, is the period during which no appreciable tidal current flows in a body of water. Slack water usually happens near high tide and low tide, and occurs when the direction of the tidal current reverses.

TIDE HYSTORY

HISTORY From ancient times, tidal observation and discussion has increased in sophistication, first marking the daily recurrence, then tides’ relationship to the Sun and Moon. Pytheas travelled to the British Isles about 325 BC and seems to be the first to have related spring tides to the phase of the Moon. In the 2nd century BC, the Babylonian astronomer, Seleucus of Seleucia, correctly described the phenomenon of tides in order to support his heliocentric theory. He correctly theorized that tides were caused by the Moon, although he believed that the interaction was mediated by the pneuma. He noted that tides varied in time and strength in different parts of the world. According to Strabo, Seleucus was the first to link tides to the lunar attraction, and that the height of the tides depends on the Moon’s position relative to the Sun. AAAThe Naturalis Historia of Pliny the Elder collates many tidal observations, e.g., the spring tides are a few days after (or before) new and full moon and are highest around the equinoxes, though Pliny noted many relationships now regarded as fanciful. In his Geography, Strabo described tides in the Persian Gulf having their greatest range when the Moon was furthest from the plane of the equator. All this despite the relatively small amplitude of Mediterranean basin tides. (The strong currents through the Strait of Messina and between Greece and the island of Euboea through the Euripus puzzled Aristotle). Philostratus discussed tides in Book Five of The Life of Apollonius of Tyana. Philostratus mentions the moon, but attributes tides to “spirits”. In Europe around 730 AD, the Venerable Bede described how the rising tide on one coast of the British Isles coincided with the fall on the other and described the time progression of high water along the Northumbrian coast. In the 9th century, the Arabian earth-scientist, Al-Kindi (Alkindus), wrote a treatise entitled Risala fi l-Illa al-Failali l-Madd wa l-Fazr (Treatise on the Efficient Cause of the Flow and Ebb), in which he presents an argument on tides which “depends on the changes which take place in bodies owing to the rise and fall of temperature.” He describes a clear and precise laboratory experiment that proved his argument. The first tide table in China was recorded in 1056 AD primarily for visitors wishing to see the famous tidal bore in the Qiantang River. The first known British tide table is thought to be that of John, Abbott of Wallingford, based on high water occurring 48 minutes later each day, and three hours earlier at the Thames mouth than upriver at London. William Thomson (Lord Kelvin) led the first systematic harmonic analysis of tidal records starting in 1867. The main result was the building of a tide-predicting machine using a system of pulleys to add together six harmonic time functions.

NOVEMBER 15, 2009

ENVIRONMENT Because intertidal organisms endure regular periods of immersion and emersion, they essentially live both underwater and on land and must be adapted to a large range of climatic conditions. The intensity of climate stressors varies with relative tide height because organisms living in areas with higher tide heights are emersed for longer periods than those living in areas with lower tide heights. This gradient of climate with tide height leads to patterns of intertidal zonation, with high intertidal species being more adapted to emersion stresses than low intertidal species. These adaptations may be behavioral (i.e. movements or actions), morphological (i.e. characteristics of external body structure), or physiological (i.e. internal functions of cells and organs). In addition, such adaptations generally cost the organism in terms of energy (e.g. to move or to grow certain structures), leading to trade-offs (i.e. spending more energy on deterring predators leaves less energy for other functions like reproduction). Intertidal organisms, especially those in the high intertidal, must cope with a large range of temperatures. While they are underwater, temperatures may only vary by a few degrees over the year. However, at low tide, temperatures may dip to below freezing or may become scaldingly hot, leading to a temperature range that may approach 30°C (86°F) during a period of a few hours. Many mobile organisms, such as snails and crabs, avoid temperature fluctuations by crawling around and searching for food at high tide and hiding in cool, moist refuges (crevices or burrows) at low tide. Besides simply living at lower tide heights, non-motile organisms may be more dependent on coping mechanisms. For example, high intertidal organisms have a stronger stress response, a physiological response of making proteins that help recovery from temperature stress just as the immune response aids in the recovery from infection. Intertidal organisms are also especially prone to desiccation during periods of emersion. Again, mobile organisms avoid desiccation in the same way as they avoid extreme temperatures: by hunkering down in mild and moist refuges. Many intertidal organisms prevent water loss by having waterproof outer surfaces, pulling completely into their shells, and sealing shut their shell opening. Limpets do not use such a sealing plate but occupy a home-scar to which they seal the lower edge of their flattened conical shell using a grinding action. They return to this home-scar after each grazing excursion, typically just before emersion. On soft rocks, these scars are quite obvious. Still other organisms, such as the algae 1 Ulva and Porphyra, are able to rehydrate and recover after periods of severe desiccation. The level of salinity can also be quite variable.

1:40 PM

Low salinities can be caused by rainwater or river inputs of freshwater. Estuarine species must be especially euryhaline, or able to tolerate a wide range of salinities. High salinities occur in locations with high evaporation rates, such as in salt marshes and high intertidal pools. Shading by plants, especially in the salt marsh, can slow evaporation and thus ameliorate salinity stress. In addition, salt marsh plants tolerate high salinities by several physiological mechanisms, including excreting salt through salt glands and preventing salt uptake into the roots. In addition to these exposure stresses (temperature, desiccation, and salinity), intertidal organisms experience strong mechanical stresses, especially in locations of high wave action. There are myriad ways in which the organisms prevent dislodgement due to waves. Morphologically, many mollusks (such as limpets and chitons) have low-profile, hydrodynamic shells. Types of substrate attachments include mussels’ tethering byssal threads and glues, sea stars’ thousands of suctioning tube feet, and isopods’ hook-like appendages that help them hold onto intertidal kelps. Higher profile organisms, such as kelps, must also avoid breaking in high flow locations, and they do so with their strength and flexibility. Finally, organisms can also avoid high flow environments, such as by seeking out low flow microhabitats. Additional forms of mechanical stresses include ice and sand scour, as well as dislodgment by water-borne rocks, logs, etc.

TIDE HYSTORY

1 Algae (Latin for “seaweed”) is a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The

FOOD WEB STRUCTURE During tidal immersion, the food supply to intertidal organisms is subsidized by materials carried in seawater, including photosynthesizing, phytoplankton and consumer zooplankton. These plankton2 are eaten by numerous forms of filter feeders—mussels, clams, barnacles, sea squirts, and polychaete worms—which filter seawater in their search for planktonic food sources. The adjacent ocean is also a primary source of nutrients for autotrophs, photosynthesizing producers ranging in size from microscopic algae (e.g. benthic diatoms) to huge kelps and other seaweeds. These intertidal producers are eaten by herbivorous grazers, such as limpets that scrape rocks clean of their diatom layer and kelp crabs that creep along blades of the feather boa kelp Egregia eating the tiny leaf-shaped bladelets. Crabs are eaten by Goliath Grouper, which are then eaten by sharks. Higher up the food web, predatory consumers—especially voracious starfish—eat other grazers (e.g. snails) and filter feeders (e.g. mussels). Finally, scavengers, including crabs and sand fleas, eat dead organic material, including dead producers and consumers.

largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and “simple” because they lack the many distinct organs found in land plants. 2 Plankton consist of any drifting organisms (animals, plants, archaea, or bacteria) that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. Plankton are defined by their ecological niche rather than their phylogenetic or taxonomic classification. They provide a crucial source of food to larger, aquatic organisms such as fish.

THE WEB OF LIFE

NOVEMBER 15, 2009

2:00 PM

THE WEB OF LIFE

The concept of food chains is a much simplified version of what actually occurs in the oceans. In any particular community or ecosystem, feeding patterns are usually far more dynamic, forming an interconnecting web of relationships. Consumers may pray on a wide range of animals at several different trophic levels, and species may change level at different stages of their lifecycle. A broad-based food web is ecologically more stable than a simple linear chain. Of course, not all the food on offer at any level is consumed; much escapes or is rejected, and eventually sinks through the water column untouched or only partially consumed. Many types of phytoplankton and zooplankton co-exist and, if they evade predation, live out their undramatic lives, energized by sunlight and stirred by swirling currents. As they die and begin to fall through the water column, decomposition by microorganisms begins almost immediately. The recycling of nutrients stimulates more primary production, forming yet another loop in the web.

THE WEB OF LIFE

NOVEMBER 15, 2009

u _ Killer Whales

t _ Leopard Seals

s _ Skuas, Petrels

r _ Penguins

q _ Crabeater Seals

p _ Sperm Whales

o _ Demersal Fishes

n _ Pelagic Fishes

m _ Pelagic Fishes

l _ Squid

k _ Large Zooplankton

i _ Baleen Whales

h _ Benthic Invertebrates

g _ Zooplankton

f _ Krill

e _ Copepods

d _ Detritus

c _ Macroalgae

b _ Bacteria

a _ Phytoplankton

Trophic Levels

THE WEB OF LIFE

2:10 PM

24 MEET THE STARFISH

NOVEMBER 15, 2009

Asteroidea Brisingida (100 species) Forcipulatida (300 species) Family Asteriidae Family Heliasteridae Family Zoroasteridae Paxillosida (255 species) Family Astropectinidae Family Ctenodiscidae Family Goniopectinidae Family Luidiidae Family Porcellanasteridae Family Radiasteridae Notomyotida (75 species) Spinulosida (120 species) Suborder Eugnathina Family Korethrasteridae Family Pterasteridae Family Pythonasteridae Family Solasteridae Suborder Leptognathina Family Acanthasteridae Family Asterinidae Family Echinasteridae Family Ganeriidae Family Metrodiridae Family Mithrodiidae Family Poraniidae Family Valvasteridae Valvatida (695 species) Sub-order Granulosina Family Archasteridae Family Chaetasteridae Family Goniasteridae Family Odontasteridae Family Ophidiasteridae Family Oreasteridae Sub-order Tumulosina Family Podosphaerasteridae Family Sphaerasteridae Velatida (200 species) Family Korethrasteridae Family Myxasteridae Family Pterasteridae Family Solasteridae

2:30 PM

MEET THE STARFISH

Lateral Canal Ampulla Radial Canal

Gonad

Pyloric Duct

Tube Foot

Pyloric Cecum Skin Gill

Gonopore

Mouth

2 6 MEET THE S TA R F I S H

NOVEMBER 15, 2009

MARINE ECOSYSTEMS AND THEIR DIVERSITY

Shoreline Communities

Experience N 2 Kingdom

Common name

Class

ANIMALIA

S E A S TA R S

ASTEROIDEA

Sea stars are star-shaped, free moving echinoderms. The body is composed of rays, projecting from a central disc. They are commonly red, orange, blue, purple, green, or have a combination of colors. Most sea stars have 5 rays ranging in length from 10 to 25 cm (4–10 in.). Some species may be much larger and have more than 5 rays; the sunflower star has 26 or more rays and often reaches 1 meter (3 ft.) in diameter.

6 1

2 5 11

3 4 7

1 - Pyloric stomach 2 - Intestine and anus 3 - Rectal sac 4 - Stone canal 5 - Madreporite 6 - Pyloric caecum 7 - Digestive glands 8 - Cardiac stomach 9 - Gonad 10 - Radial canal 11 - Tube feet As echinoderms, starfish possess a hydraulic water vascular system that aids in locomotion. The water vascular system has many projections called tube feet on the ventral face of the sea star’s arms which function in locomotion and aid with feeding. Tube feet emerge through openings in the endoskeleton and are externally expressed through the open grooves present along the bottom of each arm.

Starfish or sea stars are echinoderms belonging to the class Asteroidea. The names “starfish” and “sea star” essentially refer to members of the Class Asteroidea. However, common usage frequently finds “starfish” and “sea star” also applied to ophiuroids which are correctly referred to as “brittle stars” or “basket stars”. There are over 1800 species of living species of starfish that occur in all the world’s oceans, including the Atlantic, Pacific, Indian as well as in the Arctic and the Southern Ocean (i.e., Antarctic) regions. Starfish occur across a broad depth range from the intertidal to abyssal depths (>6000 m). Starfish are among the most familiar of marine animals and possess a number of widely known traits,such as regeneration and feeding on mussels. Starfish possess a wide diversity of body forms and feeding methods. The extent that Asteroidea can regenerate varies with individual species. Broadly speaking, starfish are opportunistic feeders, with several species having specialized feeding behavior, including suspension feeding and specialized predation on specific prey. The Asteroidea occupy several important roles throughout ecology and biology. Sea stars, such as the Ochre star (Pisaster ochraceus) have become widely known as the example of the keystone species concept in ecology. The tropical Crown of Thorns starfish (Acanthaster planci) are voracious predators of coral throughout the Indo-Pacific region. Other starfish, such as members of the Asterinidae are frequently used in developmental biology. Starfish express pentamerism or pentaradial symmetry as adults. However, the evolutionary ancestors of echinoderms are believed to have had bilateral symmetry. Starfish, as well as other echinoderms, do exhibit bilateral symmetry, but only as larval forms. Most starfish typically have five rays or arms, which radiate from a central disk. However, several species frequently have six or more arms. Several asteroid groups, such as the Solasteridae, have 10-15 arms whereas some species, such as the Antarctic Labidiaster annulatus can have up to 50. It is not unusual for species that typically have five-rays to exceptionally possess five or more rays due to developmental abnormalities. The bodies of starfish are composed of calcium carbonate components, known as ossicles. These form the endoskeleton, which takes on a variety of forms that are externally expressed as a variety of structures, such as spines and granules. The architecture and individual shape/form of these plates which often occur in specific patterns or series, as well as their location are the source of morphological data used to classify the different groups within the Asteroidea. Terminology referring to body location in sea stars is usually based in reference to the mouth

2:40 PM

to avoid incorrect assumptions of homology with the dorsal and ventral surfaces in other bilateral animals. The bottom surface is often referred to as the oral or actinal surface whereas the top surface is referred to as the aboral or abactinal side. The body surface of sea stars often has several structures that comprise the basic anatomy of the animal and can sometimes assist in its identification. The madreporite can be easily identified as the light-colored circle, located slightly off center on the central disk. This is a porous plate which is connected via a calcified channel to the animal’s water vascular system in the disk. Its function is, at least in part, to provide additional water for the animal’s needs, including replenishing water to the water vascular system. Several groups of asteroids, including the Valvatacea but especially the Forcipulatacea possess small bear-trap or valve-like structures known as pedicellariae. These can occur widely over the body surface. In forcipulate asteroids, such as Asterias or Pisaster, pedicellariae occur in pompom like tufts at the base of each spine, whereas in goniasterids, such as Hippasteria, pedicellariae are scattered over the body surface. Although the full range of function for these structures is unknown, some are thought to act to act as defense where others have been observed to aid in feeding. The Antarctic Labidiaster annulatus uses its large, pedicellariae to capture active krill prey. The North Pacific Stylasterias has been observed to capture small fish with its pedicellariae. o t h e r t y p e s o f s t r u c t u r e s va r y by t a x o n . Fo r example, Porcellanaster idae employ additional cribriform organs which occur among their lateral plate series, which are thought to generate current in the burrows made by these infaunal sea star. INTERNAL ANATOMY The body cavity not only contains the water vascular system that operates the tube feet, but also the circulatory system, called the hemal system. Hemal channels form rings around the mouth (the oral hemal ring), closer to the top of the sea star and around the digestive system (the gastric hemal ring). A portion of the body cavity called the axial sinus connects the three rings. Each ray also has hemal channels running next to the gonads. On the end of each arm or ray there is a microscopic eye (ocellus), which allows the sea star to see, although it only allows it to see light and dark, which is useful to see movement. Only part of the cells are pigmented (thus a red or black color) and there is no cornea or iris. This eye is known as a pigment spot ocellus. Several types of toxins and secondary metabolites have been extracted from several species of sea star. Research into the efficacy of these compounds

MEET THE S TA R F I S H

for possible pharmacological or industrial use occurs all around the world. LOCOMOTION The underside of a sea star. The inset shows a magnified view of the tube feet. Sea stars move using a water vascular system. Water comes into the system via the madreporite. It is then circulated from the stone canal to the ring canal and into the radial canals. The radial canals carry water to the ampullae and provide suction to the tube feet. The tube feet latch on to surfaces and move in a wave, with one body section attaching to the surfaces as another releases. Most sea stars cannot move quickly. However, some burrowing species from the genera Astropecten and Luidia are capable of rapid, creeping motion: “gliding” across the ocean floor. This motion results from their pointed tubefeet adapted specially for excavating patches of sand. Sea stars and other echinoderms have endoskeletons, suggesting that echinoderms are very closely related to chordates, animals with a hollow nerve chord that usually have vertebrae. Starfish are capable of both sexual and asexual reproduction. Most species are dioecious, with separate male and female individuals, but some are hermaphrodites. For example, the common species Asterina gibbosa is protandric, with individuals being born male, but later changing into females. FAN FACTS 1. Echinoderm is a Greek word meaning “spiny-skinned.” At the tip of each arm is one tube foot that cannot be retracted. This is a tactile organ. Just above the tactile organ is a small white eyespot that detects changes in light intensity. When searching for food, the sea star relies on chemoreception, a combined sense of taste and smell. 2. Sea stars regenerate lost rays. Regeneration is typically slow and may take one year. Some stars may have six or seven rays because two rays may regenerate instead of one. 3. The ochre sea star is more tolerant of exposure to air than other Pisaster species. They regularly withstand up to 8 hours of exposure during low tides. In laboratory conditions, they have tolerated up to 50 hours out of the water with little harm. They cannot tolerate high water temperatures or low oxygen levels. 4. Bat stars have short webbed arms reminiscent of the wings of bats, thus giving rise to their common name. 5. Colors range from solid red to mottled yellow, orange, or brown. The wide color variation is due to genetics. 6. Some sea stars, such as the giant-spined sea star, have pedicellariae—tiny pincherlike structures covering their aboral (top) surface. Pedicellariae help grind algae and other tiny pieces of debris that collect along the skin of the sea star.

28 MEET THE CRAB

NOVEMBER 15, 2009

Crab (numbers of extant and extinct species are given in brackets) Dromiacea Dakoticancroidea (6) Dromioidea (147 _ 85) Eocarcinoidea (1) Glaessneropsoidea (45) Homolodromioidea (24 _ 107) Raninoida (46 _ 196) Cyclodorippoida (99 _ 27) Eubrachyura Heterotremata Aethroidea (37 _ 44) Bellioidea (7) Bythograeoidea (14) Calappoidea (101 _ 71) Cancroidea (57 _ 81) Carpilioidea (4 _ 104) Cheiragonoidea (3 _ 13) Corystoidea (10 _ 5) Componocancroidea (1) Dairoidea (4 _ 8) Dorippoidea (101 _ 73) Eriphioidea (67 _ 14) Gecarcinucoidea (349) Goneplacoidea (182 _ 94) Hexapodoidea (21 _ 25) Leucosioidea (488 _ 113) Majoidea (980 _ 89) Orithyioidea (1) Palicoidea (63 _ 6) Parthenopoidea (144 _ 36) Pilumnoidea (405 _ 47) Portunoidea (455 _ 200) Potamoidea (662 _ 8) Pseudothelphusoidea (276) Pseudozioidea (22 _ 6) Retroplumoidea (10 _ 27) Trapezioidea (58 _ 10) Trichodactyloidea (50) Xanthoidea (736 _ 134) Thoracotremata Cryptochiroidea (46) Grapsoidea (493 _ 28) Ocypodoidea (304 _ 14) Pinnotheroidea (304 _ 13)

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MEET THE CRAB

Front View

Top View

Bottom View

MEET THE CRAB

NOVEMBER 15, 2009

MARINE ECOSYSTEMS AND THEIR DIVERSITY

Shoreline Communities

Experience N 3 Kingdom

Common name

Class

ANIMALIA

CRAB

MALACOSTRACA

The general crab body is flat and wide. Crabs have an exoskeleton, called a carapace. This is the outer shell that protects them from predators and protects the internal organs. Like other decapods, crabs have 10 jointed legs. The first pair of legs is modified into large, grasping claws called chelipeds. The compound eyes of a crab protrude from the front of the carapace and are on the end of stalks. Crab species vary greatly in size. The largest is the Japanese spider crab, Macrocheira kaempferi, at 13 ft. The smallest crabs are the male pea crabs, Pinnotheres spp., at 0.29 in. 6 1

9 10

7 8

5 4 1 - Cheliped 2 - Antenna 3 - Compound eye 4 - Legs 5 - Cephalothorax 6 - Dactylus 7 - Pollex 8 - Merus 9 - Propodus 10 - Carpus 11 - Laternal Spine LOCOMOTION Crabs can crawl forward slowly and commonly move sideways. Most crabs cannot swim, with the exception of the Portunids. Swimming crabs have the last pair of legs modified into flattened.

FEEDING Predatory swimming crabs use their chelipeds to grasp fishes and squids. Some crabs have large, blunt chelipeds for crushing shells. Other will scrape algal films from rocks or pick off pieces of seaweed. REPRODUCTION Crabs are either male or female. Female crabs can only be fertilized when they are newly molted. The male usually molts before the mating season, and must discover a female prior to her molting so that he can be present to fertilize her eggs before her new exoskeleton hardens. The fertilized eggs are attached to the female’s abdominal appendages and the embryos are brooded beneath her abdomen. Swimming larva are called zoea. After several molts into a more crablike stage in which they can swim and walk on the bottom, they are called a megalopa. Megalopas eventually molt into juvenile crabs. ECOLOGY AND CONSERVATION Many species of crabs are consumed by humans. The crab fishing industry is very powerful and developed for the capture, farming, and sale of crabs. Potential commercial overfishing may put crab populations in danger and it is important that crab fisherman follow the regulations that are set forth. Beachcombers, tidepoolers, and divers must remember not to disturb or collect any specimens that they may encounter. The removal of animals from an ecosystem may disrupt ecological processes and decrease the diversity in areas that are frequently visited. Because of their specific nutritional and physiological needs, certain animals, such as crabs have a much better chance for survival in their natural environment than in an unregulated home aquarium. EVOLUTION Crabs are generally covered with a thick exoskeleton, and armed with a single pair of chelae (claws). Crabs are found in all of the world’s oceans, while many crabs live in freshwater and on land, particularly in tropical regions. About 850 species of crab are freshwater or (semi-)terrestrial species; they are found throughout the world’s tropical and semi-tropical regions. They were previously thought to be a monophyletic group, but are now believed to represent at least two distinct lineages, one in the Old World and one in the New World. The earliest unambiguous crab fossils date from the Jurassic, although Carboniferous Imocaris, known only from its carapace may be a primitive crab. The radiation of crabs in the Cretaceous and afterward may be linked either to the break-up of Gondwana or to the concurrent radiation of bony fish, crabs’ main predators.

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BEHAVIOUR Crabs typically walk sideways (a behaviour which gives us the word crabwise). This is because of the articulation of the legs which makes a sidelong gait more efficient . However, some crabs prefer to walk forwards or backwards, including raninids, Libinia emarginata and Mictyris platycheles. Some crabs, notably the Portunidae and Matutidae, are also capable of swimming. Crabs are mostly active animals with complex behaviour patterns. They can communicate by drumming or waving their pincers. Crabs tend to be aggressive towards one another and males often fight to gain access to females. On rocky seashores, where nearly all caves and crevices are occupied, crabs may also fight over hiding holes. Crabs are omnivores, feeding primarily on algae, and taking any other food, including molluscs, worms, other crustaceans, fungi, bacteria and detritus, depending on their availability and the crab species. For many crabs, a mixed diet of plant and animal matter results in the fastest growth and greatest fitness. Crabs are known to work together to provide food and protection for their family, and during mating season to find a comfortable spot for the female to release her eggs. HUMAN CONSUMPTION Crabs make up 20% of all marine crustaceans caught, farmed, and consumed worldwide, amounting to 1½ million tonnes annually. One species accounts for one fifth of that total: Portunus trituberculatus. Other commercially important taxa include Portunus pelagicus, several species in the genus Chionoecetes, the blue crab (Callinectes sapidus), Charybdis spp., Cancer pagurus, the Dungeness crab (Metacarcinus magister) and Scylla serrata, each of which yields more than 20,000 tonnes annually. CULTURAL INFLUENCES Both the constellation Cancer and the astrological sign Cancer are named after the crab, and depicted as a crab. John Bevis first observed the Crab Nebula and its resemblance to the animal in 1731. The Crab pulsar lies at the centre of the nebula. The Moche people of ancient Peru worshipped nature, especially the sea. They often depicted crabs in their art. Western cultures have been influenced by the crab towards the game crab soccer, where players rest and move on an inverted all-fours pose.

MEET THE CRAB

FAN FACTS 1. The order decapoda contains about one-four th of t he s p ecies of cr us t a cea ns. A ll d eca p od s s ha re t he following features: a. The first three pairs of thoracic appendages are modified as maxillipeds, leaving five pairs of legs. b. The first pair of legs is modified as large claws, or chelipeds. c. Most decapods are adapted for crawling. The legs are heavy and the pleopods are used for reproductive functions rather than swimming, as seen in shrimp. d. The body is somewhat flattened and the exoskeleton is quite r igid. 2. Some of the smallest crabs, such as the Pinnotheridae (pea crabs) are commensal, living in polychaete tubes and burrows, mantle cavities of bivalves and snails, on sand dollars, in tunicates or in other animals. 3. Male fiddler crabs have one enor mously enlarged cheliped, either left or right. It often weighs as much as the rest of the crab. This cheliped is not used for feeding or defense. Rather, it is waved by the male as he stands beside his burrow entrance to advertise his status and willingness to mate. Female fiddler crabs have small, equal- sized chelipeds. 4. A crabs’ main line of defense is the chelipeds. However, other protective devices and habits are present. Some crabs carry sea anemones on their chelipeds. Some crabs, like the spider crabs, are covered with hooked setae to which foreign objects become attached. This is referred to as “decorating,” and has become highly developed in some species.

32 MEET THE SEA ANEMONE

NOVEMBER 15, 2009

Sea Anemone Endocoelantheae Actinernidae Halcuriidae Nyantheae Athenaria Andresiidae Andwakiidae Edwardsiidae Galatheanthemidae Halcampidae Halcampoididae Haliactiidae Haloclavidae Ilyanthidae Limnactiniidae Octineonidae Boloceroidaria Boloceroididae Nevadneidae Thenaria Acontiophoridae Actiniidae Actinodendronidae Actinoscyphiidae Actinostolidae Bathyphelliidae Condylanthidae Diadumenidae Discosomidae Exocoelactiidae Haliplanellidae Hormathiidae Iosactiidae Isanthidae Isophelliidae Liponematidae Metridiidae Minyadidae Nemanthidae Paractidae Phymanthidae Sagartiidae Sagartiomorphidae Stichodactylidae Thalassianthidae Protantheae Gonactiniidae Ptychodacteae Preactiidae Ptychodactiidae

3:20 PM

MEET THE SEA ANEMONE

NOVEMBER 15, 2009

MARINE ECOSYSTEMS AND THEIR DIVERSITY

Shoreline Communities

Experience N 4 Common name

SEA ANEMONE

Kingdom

Class

ANIMALIA ANTHOZOA

Sea anemones are a soft-bodied marine invertebrate. The body has a pedal disc that attaches to a substrate, a columnar body, and an oral surface surrounded by tentacles. Submerged animals usually have their tentacles extended; anemones exposed at low tide are often contracted and camouflaged with tiny shells and rocks for protection. Sea anemones are often brightly colored and may be white, green, blue, orange, or red. The size of sea anemones varies from 1.3 cm to 1.5 m (0.5 in.â&#x20AC;&#x201C;5 ft.) 1 2 3 4 7 5

8 6 1 - Tentacles 2 - Oral Disc 3 - Mouth 4 - Pharynx 5 - Complete Septum 6 - Acontia 7 - Incomplete Septa 8 - Pedal Disc LOCOMOTION Sea anemones are sedentary as adults. Though they mainly remain attached to a substrate, they do have the ability to move and relocate. RANGE All oceans, particularly diverse in tropical oceans

DIET Fishes, crustaceans, bivalves, and plankton. Some tropical species have a symbiotic relationship with zooxanthallae, a type of algae. While the anemone provides the zooxanthallae with protection and a safe home, the zooxanthallae produce food through photosynthesis for the anemone to consume. FEEDING A mass of tentacles surrounds the mouth of the sea anemone. The tentacles are in multiples of six. These tentacles contain numerous nematocysts that the anemone uses to paralyze its prey. The anemone grasps the paralyzed prey with its tentacles and carries the prey to its mouth. REPRODUCTION Some anemones will reproduce asexually by pedal laceration or by dividing into two equal parts. Sea anemones may be her maphroditic or dioecious (individuals are either male or female). LIFE SPAN Average lifespan is between 60 to 80 years. Carpet anemones may live up to 100 years. HABITAT Deep or coastal waters; attached to rocks or shells, or burrow in mud or sand. Anemones are either solitary or form colonies of clones. LIFE CYCLE Unlike other cnidarians, anemones (and other anthozoans) entirely lack the free-swimming medusa stage of the life cycle: the polyp produces eggs and sperm, and the fertilized egg develops into a planula that develops directly into another polyp. Anemones tend to stay in the same spot until conditions become unsuitable (prolonged dryness, for example), or a predator attacks them. In that case anemones can release themselves from the substrate and use flexing motions to swim to a new location. The sexes in sea anemones are separate for some species while some are hermaphroditic. Both sexual and asexual reproduction may occur. In sexual reproduction males release sperm to stimulate females to release eggs, and fertilization occurs. Anemones eject eggs and sperm through the mouth. The fertilized egg develops into a planula, which settles and grows into a single polyp. Anemones can also reproduce asexually, by budding, binary fission (the polyp separates into two halves), and pedal laceration, in which small pieces of the pedal disc break off and regenerate into small anemones.

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ANATOMY A sea anemone is a polyp, attached at the bottom to the surface beneath it by an adhesive foot, called a pedal disk, with a column shaped body ending in an oral disk. The mouth is in the middle of the oral disk, surrounded by tentacles armed with many cnidocytes, which are cells that function as a defense and as a means to capture prey. Cnidocytes contain nematocyst, capsule-like organelles capable of everting, giving phylum Cnidaria its name. The cnidae that sting are called nematocysts. Each nematocyst contains a small vesicle filled with toxins (actinoporins) an inner filament and an external sensory hair. When the hair is touched, it mechanically triggers the cell explosion, a harpoon-like structure which attaches to organisms that trigger it, and injects a dose of poison in the flesh of the aggressor or prey. This gives the anemone its characteristic sticky feeling. the sea anemone eats small fish and shrimp. The poison is a mix of toxins, including neurotoxins, which paralyzes the prey and allows it to be moved to the mouth for digestion inside the gastrovascular cavity. Actinoporins have been reported as highly toxic to fish and crustaceans, which may be the natural prey of sea anemones. In addition to their role in predation, it has been suggested that actinoporins could act, when released in water, as repellents against potential predators.[citation needed] Anemonefish (clownfish), small banded fish in various colors, are not affected by their host anemone’s sting and shelter from predators within its tentacles. The external anatomy of anemones is quite complex. There is a gastrovascular cavity with a single opening to the outside which functions as both a mouth and an anus: waste and undigested matter is excreted through the mouth/anus, which can be described as an incomplete gut. A primitive nervous system, without centralization, coordinates the processes involved in maintaining homeostasis as well as biochemical and physical responses to various stimuli. Anemones range in size from less than 1¼ cm (½ in) to nearly 2 m (6 ft) in diameter.They can have a range of ten tentacles to hundreds. The muscles and nerves in anemones are much simpler than those of other animals. Cells in the outer layer (epidermis) and the inner layer (gastrodermis) have microfilaments that group into contractile fibers. These fibers are not true muscles because they are not freely suspended in the body cavity as they are in more developed animals. Since the anemone lacks a skeleton, the contractile cells pull against the gastrovascular cavity, which acts as a hydrostatic skeleton. The anemone stabilizes itself by shutting its mouth, which keeps the gastrovascular cavity at a constant volume, making it more rigid.

MEET THE SEA ANEMONE

ECOLOGY AND CONSERVATION Some species of sea anemones have become popular in the home aquarium trade. The overharvesting of anemones is a concern in some regions. Also, removal of anemones could be damaging to some clownfish populations. Beachcombers, tidepoolers, and divers must remember not to disturb or collect any specimens that they may encounter. The removal of animals from an ecosystem may disrupt ecological processes and decrease the diversity in areas that are frequently visited. Because of their specific nutritional and physiological needs, certain animals, such as sea anemones have a much better chance for survival in their natural environment than in an unregulated home aquarium. FAN FACTS 1. In the Red Sea and Indo-Pacific Sea, clownfishes ( A p m h i p r i o n s p p. ) l i v e s y m b i o t i c a l l y a m o n g t h e tentacles of large sea anemones, a habit that would prove lethal to most other fishes. A coating of mucus probably protects the fish. Clownfishes have a mucus layer three to four times thicker than nonsymbiotic fishes. Also, the mucus appears to lack the chemical compounds that trigger nematocyst discharge. Researchers also believe t hat a cclim at ion is involved ; t he clow nfis hes m us t “ease” into the tentacles and grow immune to them. The anemone provides protection and some food leftovers for the fish; the fish in turn protects the anemone from some predators, removes dead tissue, and by its swimming, ventilates the anemones and reduces fouling by sediment. 2. The green sea anemone’s color is caused partly by pigments in its epidermis and partly by single-celled green algae living in the anemone’s tissues. Cer tain individuals living in crevices away from sunlight tend to lack the algae; they are white. 3. Some species of anemones exhibit aggression towards non-clones or ot her a nem one s p ecies. Sp ecia lized cnidocytes on searching tentacles are fired on contact with the other anemone. One or both anemones may suffer tissue damage. This behavior may provide spatial separation between species or clones. 4. A few sea anemones in European and Amer ican waters have nematoc ysts that can produce a severe toxic reaction in humans. They include the ber r ied sea anemones, Alicia mirabilis, and the Caribbean sea anemone, Lebrunia danae. The most toxic sea anemone is believed to be the West Australian, Dolfleina armata.

4:00 PM

ALOOK AT THE MUSSEL

NOVEMBER 15, 2009

Mussel Pteriomorphia (marine mussels) Arcoida (ark shells) Arcoidea Limopsoidea Cyrtodontoida Limoida (file shells and allies) Acesta Divarilima Escalima Lima Limaria Limatula Limea Mytiloida (saltwater mussels) Ostreoida (oysters and scallops) Praecardioida Pterioida (winged oysters and allies) Isognomonidae Malleidae Pinnidae Pteriidae Pulvinitidae Ramonalinidae Palaeoheterodonta (freshwater mussels) Trigonioida Myophoriidae Trigoniidae Unionoida Etheriidae Swainson Margaritiferidae Haas Mutelidae Swainson Unionidae Fleming Hyriidae Swainson Mycetopodidae Gray Heterodonta Cycloconchidae Hippuritoida Antillocaprinidae Caprinidae Diceratidae Hippuritidae Ichthyosarcolitidae Plagioptychidae Polyconitidae Radiolitidae Requieniidae Lyrodesmatidae Myoida Redoniidae Veneroida

4:10 PM

LOOK AT THE MUSSEL

NOVEMBER 15, 2009

MARINE ECOSYSTEMS AND THEIR DIVERSITY

Shoreline Communities

Experience N 5 Kingdom

Common name

Class

ANIMALIA

M USSE L

BIVALVIA

The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval. In most marine mussels the shell is longer than it is wide, being wedge-shaped or asymmetrical. The external color of the shell is often dark blue, blackish, or brown, while the interior is silvery and somewhat nacreous. In general, bivalves (mussels, clams, oysters, and scallops) can live 20 to 30 years. 2 4

3 5

1 - Stomach 2 - Posterior Adductor Muscle 3 - Rectum 4 - Foot 5 - Labial Palp 6 - Anterior Adductor 7 - Digestive Gland 8 - Byssal Retractor Muscle LOCOMOTION Mussels seldom move after settling. They live attached to rocks or other suitable substrate by byssal threads, which are secreted by the foot. HABITAT Low to mid-intertidal on rocks, wharf pilings, and sea walls; mussels thrive in areas of high wave energy and are found in dense mats referred to as “mussel beds.”

GENERAL ANATOMY The mussel’s external shell is composed of two hinged halves or “valves”. The valves are joined together on the outside by a ligament, and are closed when necessary by strong internal muscles. Mussel shells carry out a variety of functions, including support for soft tissues, protection from predators and protection against desiccation. The shell is made of three layers. In the pearly mussels there is an inner iridescent layer of nacre (mother-of-pearl) composed of calcium carbonate, which is continuously secreted by the mantle; the prismatic layer, a middle layer of chalky white crystals of calcium carbonate in a protein matrix; and the periostracum, an outer pigmented layer resembling a skin. The periostracum is composed of a protein called conchin, and its function is to protect the prismatic layer from abrasion and dissolution by acids (especially important in freshwater forms where the decay of leaf materials produces acids). Like most bivalves, mussels have a large organ called a foot. In freshwater mussels, the foot is large, muscular, and generally hatchet-shaped. It is used to pull the animal through the substrate (typically sand, gravel, or silt) in which it lies partially buried. It does this by repeatedly advancing the foot through the substrate, expanding the end so it serves as an anchor, and then pulling the rest of the animal with its shell forward. It also serves as a fleshy anchor when the animal is stationary. In marine mussels, the foot is smaller, tongue-like in shape, with a groove on the ventral surface which is continuous with the byssus pit. In this pit, a viscous secretion is exuded, entering the groove and hardening gradually upon contact with sea water. This forms extremely tough, strong, elastic, byssus threads that secure the mussel to its substrate. The byssus thread is also sometimes used by mussels as a defensive measure, to tether predatory molluscs, such as dog whelks, that invade mussel beds, immobilising them and thus starving them to death. In cooking, the byssus of the mussel is known as the “beard” and is removed before the mussels are prepared. ECOLOGY AND CONSERVATION Mussels filter dinoflagellates that produce toxins that can cause paralytic shellfish poisoning in humans. Mussels can accumulate large amount of this toxin when the dinoflagellates are most abundant. To prevent shellfish poisoning, mussels are often quarantined during times of large dinoflagellate blooms. Many mussel species are considered “invasive species” when they are introduced out of their natural range. One example is the Asian mussel, Musculista senhousia, which has invaded areas in Australia and San Diego,

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California. Beachcombers, tidepoolers, and divers must remember not to disturb or collect any specimens that they may encounter. The removal of animals from an ecosystem may disrupt ecological processes and decrease the diversity in areas that are frequently visited. Because of their specific nutritional and physiological needs, certain animals, such as mussels have a much better chance for survival in their natural environment than in an unregulated home aquarium. Also, a fishing license is required for collecting mussels to eat and they should not be collected during quarantine periods. FEEDING Both marine and freshwater mussels are filter feeders; they feed on plankton and other microscopic sea creatures which are free-floating in seawater. A mussel draws water in through its incurrent siphon. The water is then brought into the branchial chamber by the actions of the cilia located on the gills for cilliary-mucus feeding. The wastewater exits through the excurrent siphon. The labial palps finally funnel the food into the mouth, where digestion begins. Marine mussels are usually found clumping together on wave-washed rocks, each attached to the rock by its byssus. The clumping habit helps hold the mussels firm against the force of the waves. At low tide mussels in the middle of a clump will undergo less water loss because of water capture by the other mussels. REPRODUCTION Both marine and freshwater mussels are gonochoristic, with separate male and female individuals. In marine mussels, fer tilization occurs outside the body, with a larval stage that drifts for three weeks to six months, before settling on a hard surface as a young mussel. There, it is capable of moving slowly by means of attaching and detaching byssal threads to attain a better life position. Freshwater mussels also reproduce sexually. Sperm released by the male directly into the water enters the female via the incurrent siphon. After fer tilization, the eggs develop into a larval stage called a glochidium (plural glochidia), which temporarily parasitize fish, attaching themselves to the fishâ&#x20AC;&#x2122;s fins or gills. Prior to their release, the glochidia grow in the gills of the female mussel where they are constantly flushed with oxygen-rich water. In some species, release occurs when a fish attempts to attack the musselâ&#x20AC;&#x2122;s minnow or other prey species-shaped mantle flaps, an example of aggressive mimicry. Glochidia are generally species-specific, and will only live if they find the correct fish host. Once the larval mussels attach to the fish, the fish body reacts to cover them with cells forming a cyst, where the glochidia remain

LOOK AT THE MUSSEL

for two to five weeks (depending on temperature). They grow, break free from the host, and drop to the bottom of the water to begin an independent life. FUN FACTS 1. A California mussel, Mytilus californianus, may reach a length of 86 mm (3.4 in.) within its first year. 2. Humans have been using mussels as a source of food for thousands of years. Some species, such as the blue mussel (Mytilus edulis), are cultivated in order to protect the natural mussel beds from destructive harvesting practices.

Aulerpa Agardhii Alternans Annulata Antoensis Brachypus Brownii Buginensis Crassifolia Cupressoides Dichotoma Diligulata Distichophylla Ellistoniae Elongata Falcifolia Faridii Fastigiata Fergusonii Filicoides Filiformis Flexilis Floridana Harveyi Hedleyi Heterophylla Holmesiana Imbricata Juniperoides Kempfii Lagara Lanuginosa Lentillifera Lessonii Macrophysa Manorensis Matsueana Mexicana

Seaweed

Fucus ceranoides Fucus chalonii Fucus cottonii Fucus distichus Fucus evanescens Fucus gardneri Fucus nereideus Fucus serratus Fucus spermophorus Fucus spiralis Fucus tendo Fucus vesiculosus Fucus virsoides Gracilaria Laminaria Laminaria abyssalis Laminaria agardhii Laminaria appressirhiza Laminaria brasiliensis Laminaria brongardiana Laminaria bulbosa Laminaria bullata Laminaria complanata Laminaria digitata Laminaria ephemera Laminaria farlowii Laminaria hyperborea Laminaria inclinatorhiza Laminaria multiplicata Laminaria digitata Laminaria nigripes Laminaria ochroleuca Laminaria pallida Laminaria platymeris Laminaria rodriguezii Laminaria ruprechtii

Fucus

42 ADMIRE SEAWEED NOVEMBER 15, 2009

C. microphysa Murrayi Nummularia Obscura Okamurae Oligophylla Ollivieri Opposita Papillosa Parvula Paspaloides Peltata Pickeringii Pinnata Plumulifera Prolifera Pusilla Qureshii Racemosa Remotifolia Reniformis Reyesii Scalpelliformis Sedoides Selago Serrulata Sertularioides Seuratii Simpliciuscula Spathulata Subserrata Taxifolia Trifaria Urvilleana Vanbossea Veravalensis Verticillata Vesiculifera Webbiana Zeyheri

Laminaria sachalinensis Laminaria setchellii Laminaria sinclairii Laminaria solidugula Laminaria yezoensis Macrocystis Macrocystis angustifolia Macrocystis integrifolia Macrocystis laevis Macrocystis pyrifera Monostroma Porphyra Porphyra abbottae Porphyra leucosticta Porphyra linearis Porphyra miniata Porphyra purpurea Porphyra tenera Porphyra umbilicalis 4:40 PM ADMIRE SEAWEED 43

LaminariaHyperborea Largassum Vulgare

Chondrus Crispus

Caulerpa Laxifolia

Dilsea Carnosa

Codium Decorlicalum

ADMIRE SEAWEED

NOVEMBER 15, 2009

MARINE ECOSYSTEMS AND THEIR DIVERSITY

Shoreline Communities

Experience N 6 Common name

S E AW E E D

Kingdom

Class

PROTISTA VARIES

Seaweed is a loose colloquial term encompassing macroscopic, multicellular, benthic marine algae. Seaweeds are classified into three major groups; the green algae (Chlorophyta), the brown algae (Phaeophyta), and the red algae (Rhodophyta). Seaweeds are placed into one of these groups based on their pigments and colouration. Other features used to classify algae are; cell wall composition, reproductive characteristics, and the chemical nature of their photosynthetic products (oil and starch).

2 3 4 1 - Blades 2 - Float 3 - Stripe 4 - Holdfast SEAWEED CLASSIFICATION Seaweeds are classified into three major groups; the green algae, the brown algae, and the red algae. Placement of seaweed into one of these groups is based on the pigments and colouration existing in the plant. Other seaweed features that are used to classify algae

include: cell wall composition, as well as reproductive c haracter istics, and the c hemical nature of the photosynthetic products. Plant structure, form and shape are additional characteristics used to classify seaweed. AAASeaweeds are a fascinating and diverse group of organisms living in the earthâ&#x20AC;&#x2122;s oceans. You can find them attached to rocks in the intertidal zone, washed up on the beach, in giant underwater forests, and floating on the oceanâ&#x20AC;&#x2122;s surface. They can be very tiny, or quite large, growing up to 30 metres long!.AAAAlthough they have many plant-like features seaweeds are not true vascular plants; they are algae. Algae are part of the Kingdom Protista, which means that they are neither plants nor animals. Seaweeds are not grouped with the true plants because they lack a specialized vascular system (an internal conducting system for fluids and nutrients), roots, stems, leaves, and enclosed reproductive structures like flowers and cones. Because all the parts of a seaweed are in contact with the water, they are able to take up fluids, nutrients, and gases directly from the water, and do not need an internal conducting system. Like true plants, seaweeds are photosynthetic; they convert energy from sunlight into the materials needed for growth. Within their cells seaweeds have the green pigment chlorophyll, which absorbs the sunlight they need for photosynthesis. Chlorophyll is also responsible for the green colouration of many seaweeds. In addition to chlorophyll some seaweeds contain other light absorbing pigments. These pigments can be red, blue, brown, or golden, and are responsible for the beautiful colouration of red and brown algae. SEAWEED STRUCTURE Instead of roots seaweeds have holdfasts, which attach them to the sea floor. A holdfast is not necessary for water and nutrient uptake, but is needed as an anchor. Holdfasts are made up of many fingerlike projections called haptera.AAA The stalk or stem of a seaweed is called a stipe. The function of the stipe is to support the rest of the plant. The structure of the stipe varies among seaweeds; they can be flexible, stiff, solid, gas-filled, very long (20 metres), short, or completely absent. The leaves of seaweeds are called blades. The main function of the blades is to provide a large surface for the absorption of sunlight. In some species the blades also support the reproductive structures of the seaweed. Some seaweeds have only one blade, which may be divided, while other species have numerous blades. Many seaweeds have hollow, gas-filled structures called floats or pneumatocysts. These help to keep the photosynthetic structures of the seaweed buoyant so they are able to absorb energy from the sun. The term thallus refers to the entire plant body of a seaweed.

5:00 PM

SEAWEED ECOLOGY Seaweeds play very important ecological roles in many marine communities. They are a food source for marine animals such as sea urchins and fishes, and are the nutritional base of some food webs. They also provide shelter and a home for numerous fishes, invertebrates, birds, and mammals. Large seaweeds can form dense underwater forests, called kelp forests. These forests provide a physical structure that supports marine communities by providing animals with food and shelter. Kelp forests act as underwater nurseries for many marine animals, such as fish and snails. The lush blades form a dense forest canopy where invertebrates, fishes, birds, otters, and whales can find lots of tasty food and a good home. Beautiful sea slugs and kelp crabs can be seen on the blades and stipes of the seaweeds, while other small marine animals like worms find their homes in the the holdfasts. Kelp forests are a huge food source for sea urchins and other grazing invertebrates. Seaweeds are affected by the physical characteristics of their environment. Because seaweeds absorb gases and nutrients from the surrounding water, they rely on the continual movement of water past them to avoid nutrient depletion. The constant motion of ocean water also subjects seaweeds to mechanical stress. Ocean waves and currents are sometimes strong enough to rip seaweeds right off the rocks! Seaweeds cope with mechanical stress by having a strong holdfast, a flexible stipe and blades, and bending towards the substrate as waves move over them. Many seaweeds live in rocky intertidal communities. Because they cannot get up and follow the water when the tide goes out, intertidal seaweeds are subjected to the stresses associated with exposure to air and weather conditions. To survive in the intertidal, seaweeds must be able to tolerate or minimize the effects of evaporative water loss and temperature and salinity changes. When exposed to air seaweeds lose water through evaporation. Some seaweeds can dry out almost completely when the tide is out, then take up water and fully recover when the tide brings water back to them. Seaweeds living in tidepools are exposed to changes in water temperature and salinity caused by weather conditions. On hot, sunny days the water in tidepools warms up and evaporates, which increases the salinity of the water. When it rains the opposite happens, the salinity of tidepool water decreases. On cold days, seaweeds can be damaged by freezing. When the tide is out mobile intertidal animals must also try to minimize water loss. One way they do this is by seeking out a moist hiding place under some seaweed. As well as providing shelter for invertebrates, intertidal seaweeds are also a food source for animals.

ADMIRE SEAWEED

SEAWEED REPRODUCTION Seaweed life and reproductive cycles can be quite complicated. Some seaweeds are perennial, living for many years, while others are called annuals because they live for only one year. Annual seaweeds generally begin to grow in the spring, and continue throughout the summer. During powerful fall and winter storms the stipes and blades of seaweeds are often ripped off. If the holdfast manages to survive through the winter, new blades will begin to grow from it in the spring. Perennial species may also lose many of their blades during the winter and their growth is reduced. Seaweeds can reproduce sexually, by the joining of specialized male and female reproductive cells, called gametes. Like the cells that make up our bodies, the cells of adult seaweed plants are diploid, which means that they contain two sets of chromosomes. Diploid plants are called sporophytes because they produce and release spores. Spores are produced by meiosis, a cell division process that halves the number of chromosomes and forms new cells containing only one set of chromosomes (haploid cells). After they are released from the sporophyte, the haploid spores settle and grow into male and female plants called gametophytes. The gametophytes are also haploid, and they produce gametes (sperm or eggs). The sperm and eggs are either retained within the gametophyte plant body, or released into the water. Eggs are fertilized when the sperm and egg fuse together, and a diploid zygote is formed. Zygotes develop and grow into diploid sporophytes, and the life cycle continues. Seaweeds display a variety of different reproductive and life cycles and the description above is only a general example of one type, called alternation of generations. If the gametophyte and sporophyte forms look the same, it is called isomorphic (same form) alternation of generations, and if they vary in appearance, it is called heteromorphic (different form). Seaweeds can also reproduce asexually (a reproductive process that does not involve gametes) through fragmentation or division. This occurs when parts of a plant break off and develop directly into new individuals. All offspring resulting from asexual reproduction are clones; they are genetically identical to each other and the parent seaweed.

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