bottomless water by nalarivera

bottomless

water Creatures in the Deep By: Ariel Ruiz

300 meters 1500 meters 3500 meters 5000 meters 6000 + meters

Epipelagic Zone Mesopelagic Zone Bathypelagic Zone Abyssopelagic Zone Hadalpelagic Zone

bottomless

water Creatures in the Deep By: Ariel Ruiz

table of contents

Introduction

Stonefish ................................................ 6

Sea Snake ............................................... 10

Tiny Creature of Death

Kraitâ&#x20AC;&#x2122;s ..................................................... 20

II.

Blue Ringed Octopus .......................... 14

Man - of - War ....................................... 24

Medium Man Eaters

Great Shark ........................................... 34

III.

Lion Fish ................................................ 28

Blue Whale............................................. 38

Large Biters

Japanese Sider Crab ............................ 48

IV.

Bull Shark .............................................. 42

Frilled Shark ......................................... 52

Colossal Creatures

Great - Great Whale ............................ 62

Portuguese Man - of - War . ............... 56

Immortal Jellies . .................................. 66

Sturgeon . ............................................... 70

Oldest Gaints

Colossal Creatures

bottomless water

VI.

t is not known whether deep-sea gigantism comes about as a result of adaptation for scarcer

food resources (therefore delaying sexual maturity and resulting in greater size), greater hydrostatic pressure, or for other reasons. In the case of marine crustaceans, it has been proposed that the increase in size with depth occurs for the same reasons as the increase in size with latitude : both trends involve increasing size with decreasing temperature. The trend with depth has been observed in mysids, euphausiids, decapods, isopods, and amphipods. Temperature does not appear to have a similar role in influencing the size.

The Japanese Spider Crab

Frilled Sharks

Portuguese Man-of-War

HABITAT: Seabed at depths of 500 ft to 1000 ft, or more. Giant spider crabs migrate up to 160ft depth during breeding season

Food: Fish, Carrion, Aquatic Crustaceans, Detritus, other Marine Invertebrates

The Japanese Spider Crab

Plant Foods: Algae, Macroalgae

Primary Diet:

Omnivore, Detritivore

Communication: Visual and Tactile

Mutualist Species: Sponges

Although not the heaviest, the Japanese giant spider crab is the largest known living arthropod. The well calcified carapace is only around 37 centimeters long, but adult specimens can be nearly 4 meters long from one tip of one cheliped (a claw-bearing leg) to the other when stretched apart.

apanese spider crabs Macrocheira kaempferi are mostly limited to the Pacific side of the Japanese islands, Konshu and Kyushu, usually at a latitude between 30 and 40 degrees North. They are found most often in the Sagami, Suruga, and Tosa bays, as well as off the coast of the Kii peninsula. However, the crab has been found as far south as Su-ao, in Eastern Taiwan. This is most likely a onetime event; it is very possible a fishing trawler

or extreme weather to perhaps have carried this

individual much further south than its home range. The carapace of a Macrocheira kaempferi is very sub-circular and pear-shaped (pyriform), narrower towards the head. Females tend to have wider, although slightly smaller, abdomens than males. Spiny and stubby tubercles (growths) cover the carapace, which ranges from dark orange to light tan in color and sometimes a light red.

It possesses no cryptic coloration and is unable to change color. The rostrum (an extension of the carapace above the head) is shaped into two slender spines that jut out from between the eyes. The base of the well-developed antennae is fused with the epistome (the area above the mouth). The carapace tends to stay the same size throughout adulthood, but the walking legs and chelipeds lengthen considerably as the crab ages. Spider crabs are known for having long, spindly legs. Like the carapace, the legs are also orange, but may be blotchy and mottled with both orange and white. The walking legs of Macrocheira kaempferi end simply in inwardly-curving dactyls (the movable part at the tip of a walking leg). These assist the creature in climbing and hooking onto rock, but prevent it from picking up or grasping objects. In adult males the chelipeds are far longer than any of the walking legs, with the right and left chelipeds being of equal size. Females, on the other hand, tend to possess chelipeds that are shorter than the other walking legs. The merus (upper portion of 76 longer than the palm (portion of the leg) is slightly the leg containing the unmoving part of the claw), but comparable in shape. The weak movable finger is small, taking up less than a quarter of the palm. Although long, the legs are often weak. One study reported that nearly three quarters of these crabs are missing at least one limb, most often one of the first walking legs. This is because the limbs are long and poorly-jointed to the body of the organism, and tend to come off due to predators and nets. Spider crabs can usually survive with up to 3

walking legs missing. The walking legs often grow back during the successive molts. Japanese spider crabs most often inhabit the sandy and rocky bottom of the continental shelf and slope at an average depth of 150-300 meters. They have, however been found at depths of 600 feet. During spawning season the crabs spend most of their time in shallower waters around 50 meters. In Suruga Bay, at depths of 300 meters, the temperature is around 10 degrees Celsius. Younger crabs tend to live in shallower areas with warmer temperatures.

Trophic Strategy Macrocheira kaempferi is an omnivorous scavenger. These large crustaceans generally do not hunt, but instead crawl along and pick at dead and decaying matter along the sea bed. This includes both animal and plant matter. They occasionally eat living kelp and algae. Although they move slowly, giant crabs occasionally hunt for small marine invertebrates that they can catch easily. Mariners used to tell tales of M. kaempferi dragging sailors underwater and feasting on their flesh. This is generally regarded as untrue, although it is certainly plausible that one of these crabs would feast upon the dead body of a sailor who had previously drowned.

Associations Macrocheira kaempferi is not an active predator, as it mainly scavenges the sea floor for dead and decaying matter. While nearly all spider crabs tend to decorate their carapaces with sponges

Size:

Range Mass: 16 to 20 kg. Range length: 3.7 (high) m. Average length: 3 m.

Depth:

Range Depth: 50 to 600 m. Average depth: 200 m.

Features:

Ectothermic, Heterothermic, Bilateral Symmetry

Lifespan:

Wild: 100 years

Development:

Life Cycle: metamorphosis

Breeding interval: Giant Japanese spider crabs

mate once a year, seasonally between January and April

Breeding season: Early spring

Offspring range: 1,500,000 eggs (high).

and other items, M. kaempferi does it less than others because it has so very few predators and therefore it has no need to be camouflage. Sponges provide camouflage and protection for the crab; the spider crab carries the sponge to new areas and provides it with drifting food.

Behavior Not much is known about communication in Macrocheira kaempferi. They often scavenge for food alone, and there is little communication between members of the species, even when isolated with other spider crabs in aquaria. The antennae are greatly reduced. The eye stalks are also very short and stubby. Since these crabs are not active hunters and do not have many predators, their sensory systems are not as acute as those of other decapods in the same area.

Life cycle This species goes through two zoeal stages and one megalopa stage. The zoeal stages generally last between 12-37 days, a shorter duration than other crabs in the same region. The megalopa stage typically lasts an average of 30 days. During the first molt (the prezoeal stage) the hatchlings writhe about, eventually slowly drifting to the sea bed. Here, each hatch-ling thrashes about until it flicks up the spines on its carapace. This dislodges the cuticle, and allows it to wriggle out by twisting and pulling until it frees itself. The optimal rearing temperature for all larval stages is between 15-18 degrees Celsius, while

the survival temperature is 11-20 degrees Celsius. Larval stages can most likely be found at shallower depths, then later move to deeper waters. In Suruga Bay, the temperature at 300 meters is around 10 degrees, and only adults may be found at these depths. These survival temperatures are much higher than those of other decapod species in the region. In the lab, at optimum growth conditions, only around 75% survive the first zoeal stage. This number increasingly drops to around 33% for the second zoeal and megalopa stages.

Life Relatively little is known information regarding the longevity of this species. It is often reported that one of these crabs may live to be 100 years old in its natural habitat, but this may be conjecture. Other reports indicate that M. kaempferi generally cane live for over half of a century out in the wild. In captivity that still remains unknown.

Reproduction These spider crabs mate seasonally during early spring, from January through March. Mating behavior is rarely observed. Male crabs hold sperm in spermatophores, which are inserted into the femaleâ&#x20AC;&#x2122;s abdomen using the first two chelipeds. Even though juvenile stages are well-documented in laboratories, reproduction information concerning M. kaempferi in its natural habitat is sparse.

Key Reproductive Features: Seasonal breeding, gonochoric, dioecious (sexes separate), sexual, fertilization (Internal), oviparous

Parental Investment:

female parental care, per-hatching/birth (Protecting: Female)

n the past one hundred years of ocean science has been distinguished by dramatic milestones, remarkable discoveries, and major revelations. This book is a clear and lively survey of many of these amazing findings. Look inside and see what lies deep underneath, and find out which sea creatures are friendly and which are foe. This book places a current understanding in the context of history. Get informed on topics like tiny sea creature that will kill you, coral reefs, and the great sea creatures that are still around today. The productivity of the sea, and the geologic revolution that changed all knowledge of the earth in the twentieth century and may help you survive the depth.

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