| For a pretty straightforward design, the sea cucumbers, (weli, or loli) of Hawaii come in an amazing variety of "flavors": you've got your white-spotted and your yellow-spotted, your spiky and your leopard. For the more adventurous, there's the stubborn sea cucumber, the impatient, the prickly, the difficult, and the paradoxical sea cucumber. Whoever is naming these things might want to stop by the shrink's office for a little tune-up. But whatever you call them, these fluid-filled enchinoderms of our tidal pools, reef flats and bays do their job in the ecosystem by scavenging up organic debris, then expelling out the remainder to fertilize the algae. Their mouth is located on one end, and is ringed with feeding tentacles. While their "loaf of bread" shape may deceive you, these echinoderms are related to sea urchins and sea stars. The cukes' spines are reduced but clearly present on some of them; their shape is mainly supported by the water that fills their muscular body. Like other echinoderms, they are bottom dwelling, (most) have tube-feet for location and gripping power, and have a five-part body layout (though this is usually only apparent internally). Inside, a special structure called a respiratory tree enables the cuke to extract oxygen from the seawater. I once picked up a sea cucumber at a touch pool, and it drained the water from this structure, leaving me holding a flat tire. |
Seeing as these creatures are soft and slow, and without the spiny protection of their cousins, you might think they are easy pickings, but sea cucumbers have a arsenal of defenses. Their squishable bodies allow them to tuck under rocks and in small crevices. Some simply taste bad due to noxious chemicals in their skin. But here's something unique: some cukes expel Cuvierian tubules from their anus - sticky threads that entangle predators, and may be accompanied by the release of a toxin called holothurin. Take that! And just in case, some sea cukes can also eviscerate, which essentially means that they can expel some of their insides, sneak away, and then spend a good portion of time regenerating.
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October 2014
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