SEAW ORDS TheMarineOption Program Newsletter
June2021
Volume XXXVI, Number 6
Aloha, and welcome to the June issue of Seawords! We're certainly glad to see the start of summer vacation! Travel along with a wide array of sea creatures this month, from sea turtles in the Sargasso (4) to sponges in the deep sea (8). Learn about how sharks navigate on page 20! And if you're looking for ways to revamp your wardrobe for summer, look no further than our quiz on page 10, where you can take inspiration from some of the most fashionable fishes on the reef! W hat would you like to see more of in Seawords?Send in your thoughts, and follow us on Twitter and Instagram at @mopseawords!
Zada Boyce-Quentin, SeawordsEditor, & Matilda Phillips, Associate Editor
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Contents 2: LETTER FROM THE EDITOR 4: SARGASSO SEA ASTURTLE NURSERY 8: ON THE MOVE: DEEP SEA SPONGES 10: W HAT FISH FASHION SHOULD YOU CHANNEL 14: CREATURE OF THE MONTH 20: SHARKSUSING MAGNETIC FIELDS
Photo Credits Fr ont Page: Nautilus. By: Sivanesan S., Flickr. Tabl e of Contents: Clownfish. By: Daniel Smith, Flickr. Back Cover : Nudibranch. By: Elias Levy, Flickr.
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Sar gasso Sea as Tur tl e Nur ser y By: Geor gia Johnson-King, UHM MOP Student 4 | Seawords
Sargasso sea. By: freezingmariner, Flickr.
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A new study published in the May edition of The Royal Society Biological Journal has found that the Sargasso Sea is the perfect nursery for juvenile sea turtles. Due to both technological and logistical limits in the tracking of sea turtles, data concerning the so called ?lost years?of juveniles have thus far remained unquantified. However, new offshore tracking systems which utilize a tag attachment for young turtles have provided data that support the Sargasso Sea as a kind of turtle playroom. Researchers caught 22 hatchling turtles, 10 green and 12 loggerheads, emerging from nests in Florida before returning them to the Florida Atlantic Nursery Marine Laboratory. The turtles were raised until they were 3-9 months of age or greater than 300 grams in weight. The transmitters could be affixed when the hatchlings reached 300 grams. These lightweight solar-powered transmitters were originally used to track birds and were proven to have no effects on turtle growth and behavior after a few months, the transmitters were designed to fall off.
Sargasso sea. By: rjsinenomine, Flickr. 6 | Seawords
Sea turtle. By: Pierre Pouliquin, Flickr.
Tracking lasted between 10 and 152 days and found that the majority of the turtles?orientation was statistically significant, revealing that the majority of the turtles navigated towards the Sargasso Sea. As sea turtles require warmer temperatures and places to frequently surface, the Sargasso Sea makes a perfect nursery. The Sargasso Sea is a specific region of the Atlantic Ocean known for being the only sea without shores. Instead, a number of currents make up the borders of the sea. To the north is the North Atlantic Current, East is the Canary Current, South is the North Atlantic Equatorial Current and the western boundary is the Gulf Stream. This study sheds light on the journey made by juvenile sea turtles, and scientists hope that this information will assist in efforts to conserve turtle populations, especially during their first years, when they are particularly vulnerable to predation and other dangers.
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On the Move: Deep Sea Sponges By: Alexandrya Robinson, UHM MOP Student
Deep sea sponge. By: NOAA Ocean Exploration, Flickr. 8 | Seawords
W hen thinking about the deep ocean floor, pictures may come to mind of barren hills of sand, maybe dotted with the occasional prints from crab legs. But other organisms call the depths their home, and recently one phylum has been the source of discussion: sponges. Sponges are simple, multicellular filter-feeding organisms with no tissue diversification. Scientists from the Helmholtz Centre for Polar and Marine Research, after looking at high resolution images of arctic depths, found mysterious tracks across the ocean floor that baffled them until they followed those tracks, which led to sponges, showing evidence of mobility. Sponges were previously accepted as sessile organisms that sometimes passively moved from one area to another, transported by other organisms or even water currents. However, in deep arctic water, where these images were taken, there are no strong currents. That, coupled with an almost snail-like ooze trail, were definite indicators of the sponge?s path. These images provide new evidence that sponges are not as immobile as previously thought. 69%of the images taken by the Helmholtz Centre for Polar and Marine Research showed these trails, meaning this is not just an isolated occurrence. How was this fact missed for so many years?The answer to that is simply the time intervals of observation. Because sponges move very slowly, while lab experiments have observed contraction and relaxation of the sponge?s skeleton which can cause movement up to four millimeters a day, this phenomenon has not been seen in the wild until this point due simply to the time scientists can realistically spend observing individual sponges in the wild. Sponge movement is already an odd concept due to the lack of muscle tissues in Phylum Porifera. The skeletons of sponges are very dense and, in some cases, highly rigid. The question, then, is how these sponges are moving and why. Currently there is no definitive explanation, only the hypothesis that sponges are moving around the ocean to potentially seek out sources of food, move away from poor conditions, or to disseminate their offspring. Sponges are incredibly important to deep-sea ecosystems, and this new information is another piece of the puzzle scientists are hoping to understand.
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W hat Fish Fashion Should You Channel This Summer? The reef is home to a diverse array of stunning FISHtonistas, and with summer upon us, it's the perfect time to draw inspSEAration from their bold and colorful statement scales. W AVE in some fresh pieces for your wardrobe this month by taking our quiz to determine which ocean-dwelling style icon should be your influence!
W hat col or s/ patter ns do you most fr equentl y w ear ? A. Bold stripes B. Bright pastels C. Solid colors and simple lines
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How do you r espond to confl ict? A. Hide! That's what my home defense system is for! B. Live and let live! We're all in this together :) C. Defend my territory!
W hat's your favor ite summer jam genr e? A. Circus music B. Experimental lo-fi C. Fast-paced pop
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Mostl y As: Congratulations! Your summer fashion icon is Clark's anemonefish, or Amphiprion clarkii. These fish protect themselves from the venom of the anemones they call home by coating themselves in a layer of mucus (which we don't recommend as a summer style.) You can channel this fashionable fish by: - Opting for stripes - Selecting vibrant statement pieces - Finding a flashy accessory sure to deter predation Clark's anemonefish. By: Klaus Stiefel, Flickr.
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Mostl
Congratulations! Yo icon is the palenose psittacus. These fish their beak-like mo them to scrape alg Parrotfish sleep in s mucus to protect You can channel this - Investing i - Looking for hol - Finding a bold complement Palenose parrotfish. By: Ken_Ichi Ueda, Flickr.
l y Bs:
our summer fashion parrotfish, or Scarus are recognizable by ouths, which allow gae from the reef. secreted bubbles of ct from parasites. s fashionable fish by: in gauzy layers ograph/ neon pieces d statement lip to t your wardrobe
Mostl y Cs: Congratulations! Your summer fashion icon is the lagoon triggerfish, or Rhinecanthusaculeatus. These fish defend their territory aggressively, and prefer shallower parts of the reef with many rocks. W hen disturbed, they've been observed grunting to scare off intruders. You can channel this fashionable fish by: - Choosing a bold eyeliner - Picking simple pieces with clean lines - Finding a pop of color to emphasize your outfit Lagoon triggerfish. By: Michelle Bender, Flickr.
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Cr eatur e of the Month: Chamber ed Nautil us By: Hal ey Chasin, UHM MOP Student
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Nautilus. By: Klaus Stiefel, Flickr. JUNE 2021
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Chambered nautiluses, referred to by scientists as ?living fossils?due to the fact that they have remained generally unchanged for the past 500 million years, are defined by their beautifully patterned external shells. The chambered nautilus is a kind of cephalopod, closely related to cuttlefish, squids, and octopuses. They are found in tropical Western Pacific waters (though not in the Hawaiian islands, capable of living in both shallow waters (300 feet or 90 meters or less) and the very deepest depths (1500 feet or 450 meters). This means that the nautilus can tolerate large ranges in bothpressure and temperature. There are several species in the Nautilidae family, with five in the genus Nautilus (N. belauensis, N. macromphalus, N. pompilius, N. repertus, and N. stenomphelus) and two species in the genus Allonautilus(A. perforatusand A. scrobiculatus). The largest nautilus species, the emperor nautilus is 8-10 inches in diameter, with a body weighing 2.8 pounds. The smallest, meanwhile, is the bellybutton nautilus at about 6-7 inches. Members of genus Allonautiluswere actually thought to be extinct but were recently re-discovered in the South Pacific. Allonautilusspecies have slimy, hairy shells, which, among other body plan changes, make them characteristically different from other nautiluses. Nautilus. By: Klaus Stiefel, Flickr.
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Chambered nautilus. By: margencero, Flickr.
Though nautiluses have poor eyesight, with their simple eyes and no lens, like ?hollow bulbs on a stalk?only capable of perceiving light and dark, they are active predators. They feed on shrimp and other crustaceans using 38-90 tentacles which retract into a sheath. These tentacles are lined with alternating grooves and ridges to grip objects. These catch prey and pass it along to the jaws, then to the radula, which shreds the food. The shell of the nautilus is constructed similarly to snails. It is produced by the mantle tissue and has a genetically hardwired shape called a logarithmic spiral. The shell is separated or compartmentalized into chambers- four in newly hatched nautiluses and thirty in mature individuals. The animal lives in the outermost, or newest, portion of the shell, and as it grows it moves forward. The animal can completely withdraw inside the outer chamber and can even cover itself with a leathery material called the ?hood?as a defense mechanism. The shell is counter-shaded, meaning that when you look down, the animal is darker with irregular stripes on top, and when you look up the animal appears lighter due to the pattern. Nautiluses control buoyancy changes by adjusting the amount of seawater in their shell. The siphuncle is a calcareous tube which connects all interior chambers, and has live tissue running through the shell that serves to pump fluid out of the vacant chamber, thereby adjusting the buoyancy. JUNE 2021
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The nautilus shell is also designed to maintain neutral buoyancy, as the older sections of the shell are filled with gas to counter the weight of the animal.Nautiluses swim in a see-saw motion by way of jet propulsion, pulling water into the mantle cavity and blowing it out through the siphon. Experiments at the W aikiki Aquarium have been done to determine what temperature is most optimal in order for nautilus eggs to develop. Oxygen-18 isotope concentrations were used to track changes because it is a tracer and is heavier, so is found farther from the surface. Oxygen-18 values of each septum, or wall between chambers, can be interpreted as the reliability of the temperature in the water where the septa is formed. In the earlier life history stages, the nautilus embryo starts off with a smaller amount of isotopic oxygen-18. Increases in isotopic oxygen-18 between embryonic and post-embryonic septa reflect preparation for colder, deeper water after hatching. Isotopic values of the embryonic septa are thought to reflect the environment inside the eggs,whereas after the embryonic stage it reflects the outside environment, representing changes in habitat after hatching.
Nautilus shell. By: rainy city, Flickr.
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Close-up nautilus. By: anataman, Flickr.
Changes in isotopic oxygen-18 in the wild are due to changes in both morphology and environment. Understanding these isotopic concentrations is still a work in progress, but it has allowed aquariums and marine research centers to determine the temperature at which eggs best develop. In the Cretaceous period, nautiluses did not experience the same shift in oxygen-18 compared to extant nautiluses.This indicates that nautiluses during this time period did not relocate to habitats differing in temperature and pressure after hatching. Nautiluses have been the subject of poetry, artwork, math, and jewelry, and they have also inspired the names of technology from submarines to exercise equipment. In Greek culture, the chamber of the nautilus is a symbol of perfection, and their shell shape has been recognized as a natural mathematical logarithm. The best time to catch nautiluses is in spring and early summer in deeper waters.Often sought after for their shells, as well as the shell?s nacre, or inner layer,the six living nautilus species are slowly declining in population.This is especially concerning given the difficulty of cultivating nautiluses from eggs in captivity, and scientists are seeking ways to preserve the numbers of these fascinating creatures. JUNE 2021
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Sharks Using Magnetic Fields By: Brenna Loving, UHM MOP Student Bonnethead shark. By: Kevin Bryant, Flickr.
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Animals of the ocean known for their great migratory journeys, such as whales, have been proven to use the earth?s magnetic field as a navigational tool. This allows them to return to the same spots in the vast ocean year after year. A similar pattern can be observed with bonnethead sharks specifically, as they return to the same estuary annually. Scientists from Florida State University Coastal and Marine Laboratory tested this knowledge with the bonnetheads in their own backyard off the coast of Florida, under the hypothesis that sharks use their sensitivity to the earth?s magnetic field to guide their way. PhD graduate Bryan Keller and his team were able to set up a test to determine how much sharks relied on the earth?s magnetic field to find their way back to these estuaries. Keller?s idea was that the bonnetheads would travel north when faced with a southern polarity, vice versa, and have no preference or change when the magnetism was of their destination. The study consisted of 20 juvenile bonnethead sharks that were placed in a magnetic field found hundreds of miles away from the site, and the individuals behaved in response to the magnetism just as hypothesized. Similar to other species that rely on the earth?s magnetism for navigation, sharks have sensory organs over their snout that detect electromagnetic waves and magnetic polarization. However, the details of these sensory organs are still widely debated amongst scientists. This newly solidified information could be the source in finding new ways to prevent shark bycatch in fishing, which is a monumental threat to sharks and other bycatch victims. A study by Vincent Raoult from the University of Newcastle in Australia proved that there could be a way to use magnetism to ward off sharks from fishing areas in efforts to reduce their bycatch. In the study, Raoult and his team placed powerful magnets on bait traps set out by fishermen that are used to catch other fish, but often attract unwanted predators like sharks. After 8 months of monitoring 1,100 traps with the magnets, Raoult found that the magnetic traps saw a 30%reduction in shark bycatch and a 30%increase in snapper caught by them. More research must be done in determining the most efficient and effective ways of utilizing magnetism to deter sharks and other victims of bycatch from the affected areas, but verifying the hypothesis of sharks relying on and reacting to changes in the earth?s magnetic field is a fantastic step in finding ways to save shark populations around the world.
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Vol u m e XXXVI, Nu m ber 6 Editor : Zada Boyce-Qu en tin Dr. Cyn th ia H u n ter (em in en ce gr ise) Jeffr ey Ku wabar a (em in en ce gr ise) W r itin g Team : Br en n a Lovin g, Ch l oe M ol ou , Caitl in Tsu ch iya, Al exan dr ya Robin son , Geor gis Joh n son -Kin g, H al ey Ch asin , an d An n am ar ie Coffar o Seawor ds- M ar in e Option Pr ogr am Un iver sity of H awai ?i , Col l ege of Natu r al Scien ces 2450 Cam pu s Road, Dean H al l 105A H on ol u l u , H I 96822-2219 Tel eph on e: (808) 956-8433 Em ail : <seawor ds@ h awaii.edu > W ebsite: <h ttp:/ / www.h awaii.edu / m op> Seawor ds is th e m on th l y n ewsl etter n ewsl etter of th e M ar in e Option Pr ogr am at th e Un iver sity of H awai?i. Opin ion s expr essed h er ein ar e n ot n ecessar il y th ose of th e M ar in e Option Pr ogr am or of th e Un iver sity of H awai?i. Su ggestion s an d su bm ission s ar e wel com e. Su bm ission s m ay in cl u de ar ticl es, ph otogr aph y,ar t wor k , or an yth in g th at m ay be of in ter est to th e m ar in e com m u n ity in H awai ?i. an d ar ou n d th e wor l d. All photos ar e taken by M OP unless other wise cr edited.