Thursday, September 29, 2011

Creature Feature: Upside-down Jellyfish.

Cnidarians, as creatures, are underrated. Sure, they don't have claws, teeth, or even spinal cords, but that does not make them any less fascinating than large predatory mammals. The only two biologically-immortal animals in existence are cnidarians. All those pretty fluorescent proteins used in labs come from jellyfish and anemones. A box jellyfish will kill you more quickly than a tiger. Hell, cnidarians even have a sort of agriculture.

Cassiopea jellyfish are also aptly called upside-down jellyfish. They are found in swamps and mudflats of hot, humid areas like Florida, Hawaii, and Southeast Asia. Instead of stinging like normal jellies, they secrete their venom into a mucous cloud above them; said fluid is extremely itchy to swim through. They are not born upside-down, but do eventually spend their lives as living, tentacled pancakes secreting itchy fluid into the water.

Upside-down jellyfish often have algae growing on their tentacles. Specifically, zooxanthellae, a type of protist algae (as opposed to stuff like cyanobacteria), take up residence in the jellies' tentacles, making them look more like flora than fauna. The algae get a more or less safe place while the jellyfish get food. They even get free water circulation from the Cassiopea's pulsating bell. It all works out.

Of course, some things take advantage of these jellies' unusual anatomy. Sea urchin crabs steal them and put them on their backs as goofy-looking, living protection. Loggerhead sea turtles and ocean sunfish love these jellies (they're probably whole foods!). Admittedly, when you look like a salad bar, you are asking to be food no matter how toxic you are.

Cnidarians: Is there anything they can't do? Yes, we're pretty sure they can do tentacle rape, too.

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