08 January 2008

Stars and Jellies



The beach at Perdido Key was littered with Portuguese Man O'War Jellies and a kind of sea star with which I am unfamiliar. The sea star had broad black and white bands on it's arms, and the arms swirled out from it's body in a spiral like this:

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Underneath, the orangey tube feed waved in the damp air, trying to find the sandy substrate that it was supposed to be sitting on. The waves had flipped them upside down, feet reaching for the sky, finding nothing but air on which to feed.



The Man O'War were impressive! A few huge animals washed ashore, but most were man o warlets, little grape sized blue-purple floats and tentacles, sending jolts of pain into any unsuspecting passersby. Even dead, these colonial siphonophores can hurt!



Even the sand grains look large next to these tiny Man O'War babies, but they still pack a mean sting!



On the north shore, cannon ball jellies lay at the water line, gently swaying in the lapping waves.



While these jellies don't sting, they still have plenty of feeding tentacles and a powerful bell to propel them through the water with a modicum of self-control.



Though largely directed by the currents and waves, they are elegant 'swimmers' in a relatively still pool.



I'm not sure who started calling these animals groups 'starfish' and 'jellyfish'. Maybe it was conventional to call anything in the sea a fish, though there are far more invertebrates than fish, and the biggest 'fish', the whales, are mammals. Sea stars and jellies have such perfect names for them -- Echinoderms for the spiny skinned, radially symmetrical sea stars, and Cnidarians (Coelenerates) for the watery, tentacled, often stinging, jellies. How are such apt names discarded in favor of the slippery fish? Fish are amazing in their own right, but jellies and sea stars deserve recognition for the unique critters they are.

Small bits of Sargassum washed in on the winter tides as well. Sometimes, huge rafts arrive with well-adapted sargassum hitch hikers.



It scares me to think that some countries are now harvesting the Sargassum rafts caught out in the Atlantic currents, in the Sargasso Sea. These drifting algal mats provide important habitat in the deep oceans for fish, crabs, and hatchling sea turtles.



The most prevalent theory for the early "Lost Years" is that little loggerheads swim out to the ocean currents in their first days, eventually finding these Sargassum mats where ocean currents coincide. The mats provide coverage from birds feeding overhead and fish feeding from below. Hatchlings thrive here until they are large enough to evade most predators and swim along with the North Atlantic Gyre, feeding for a while longer until they return to near-shore feeding grounds once they reach 'dinner plate size'. Protecting these critical habitats needs to be a concern for all sea turtle biologists and enthusiasts everywhere!

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