Sea stars, sea cucumbers and other echinoderms
What are sea urchins? Members of Class Echinoidea, they’re distant cousins of starfishes that boast imposing defenses and bad reputations. Do sea urchins sting? Not really. It’s more that they impale. But, if you don’t bother them, these oceanic pincushions won’t bother you. The trick is in not accidentally bothering them. RATHER THAN APPRECIATING SEA URCHINS, MOST PEOPLE FLEE FROM THEM, CAREFULLY. After all, the likely result of interacting with these oceanic pincushions while doing
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Basket stars are the starfish relatives you’re least likely to see in their full glory. Key basket star fact: They do their work of unfolding their tangled arms and capturing passing prey in the dead of night. Another: If you come across one during a night dive and stop to look at it – shining a light on it, of course – it’s going to fold right up and not quite disappear in front of
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Coral reefs are constantly being built up and simultaneously torn down, but Crown of Thorns Starfishes throw that equation out the window. Left to their own devices during population outbreaks, Acanthaster planci devour coral polyps and devastate reef habitats. Herewith: Crown of thorns starfish facts. IF CROWN OF THORNS STARFISHES HAD A THEME SONG, it would be Darth Vader-type music. So destructive are these rogue echinoderms that their very name is synonymous with bad news
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UNLIKELY ANIMALS THEY MAY SEEM TO OUR EYES, but feather stars are full-fledged members of the animal kingdom. Here’s a key feather star fact: They may seem to be fixed in place in their perches on coral heads or sponges or sea rods, but these crinoid creatures eat, reproduce and move like other animals. As a bonus, they’re often beautiful and compelling. TECHNICALLY, FEATHER STARS HAVE ARMS JUST LIKE THEIR STARFISH AND BRITTLESTAR COUSINS. At
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If you think of brittlestars as just a variation on the familiar, pointy starfish, think again. They’re made quite differently, they act differently and they live quite a different lifestyle. It’s all in the long, whip-like arms. BRITTLESTARS ARE MORE THAN JUST TRADITIONAL STARFISHES WITH LONG, SINUOUS ARMS AND LAID-BACK ATTITUDES. Actually, there are many differences between brittlestars and star-shaped starfishes, both in body design and behavior. In contrast to sea stars, brittlestars have flexible,
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IF IT LOOKS LIKE A PIG AND IT WALKS LIKE A PIG AND IT’S UNDERWATER, THEN IT MIGHT BE A…SEA CUCUMBER. Specifically, a member of the genus Scotoplanes. Or, to its multitudinous fans worldwide, a sea pig. Whereas most of us are used to seeing sea cucumbers that actually more or less resemble cucumbers in body shape, Scotoplanes species like S. globosa really do remind people of pigs. Plump, pink and sporting rather porky “legs,”
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BOTH LITTLE KIDS AND MARINE BIOLOGISTS KNOW STARFISH BY THEIR FIVE ARMS. The starfish anatomy that lurks underneath a starfish’s bumpy skin is another thing (To be clear, the biologists know sea star facts, the rest of us not so much). There are 1,500 to 2,000 species of starfish, or sea stars, found in oceans worldwide, in pretty much every depth and type of habitat. They’re all alike in general architecture but come in a myriad
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WITH FIVE ARMS STRETCHING IN FIVE DIRECTIONS, you’d think that starfish could move along the seafloor like Indiana Jones. In fact, usually they creep along on hundreds of little tube feet that line the undersides of those arms. But, researchers studying how starfish walk found something else: sometimes starfish bounce along for speed. As echinoderms in Class Asteroidea, starfish walk by operating their multitudes of little tiny feet through intricate networks of fluid-filled canals. With
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IT MAKES SENSE THAT YELLOWLINE ARROW CRABS would want to hang out with long-spined sea urchins. After all, it should be a gimme that these crustaceans with 10 long, thin legs would seek to blend in with urchins whose most visible features are long, thin spines. On the other hand, the sources seem to put Stenorhynchus seticornis all over the place – atop sponges, sea fans and other gorgonians, under and next to sea anemones.
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A POST HERE SEVERAL MONTHS AGO closed with the “Really Odd Fact” that blenny-like pearlfish (Periclimenes imperator) have a habit of taking up residence in the … well…rear ends of sea cucumbers. The overall post, “Sea Cucumbers – Superheroes of the Sea,” was about the fact that sea cucumbers, often ignored as inert, unimportant creatures, actually had a lot to recommend them. THE PEARLFISH/CUCUMBER EQUATION The pearlfish/cuke interaction is generally described as commensal relationship, but that term implies a
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