surface. In the Marshall Islands, similar sea cucum- 

 bers are pounded and the mangled remains dropped 

 into pools at low tide, stupefying the fish enough that 

 they can be caught easily. Yet the poison is not feared 

 by the natives. It is harmless to human skin, and fish 

 caught through its use are often eaten raw with no ill 

 effects. 



About 500 different kinds of sea cucumbers have 

 been found, living almost exclusively on or in the 

 bottom sediments. Most of them are dull colored, 

 and only a few have contrasting spots or stripes. Yet 

 they pursue their lethargic way of life on minute food 

 in so many difTerent levels of the sea that a surprising 

 variety of form and body build is represented. 



Something in common can be seen between a child 

 solemnly licking its fingers to clean them of jam, and 

 a big sea cucumber in its normal method of feeding 

 with ten or more profusely branched tentacles, each 

 like a shrubby tree. The cucumber spreads its tenta- 

 cles over the sea bottom and rubs them around, gath- 

 ering food particles in the mucus coating. Then, one 

 at a time, the animal thrusts a loaded tentacle into 

 its mouth, closes fleshy lips around it, and pulls out 

 the tentacle all clean and ready for reloading. 



Sea cucumbers acting in this way can be found in 

 cooler waters between low-tide mark and 1200 feet 

 below the surface. Ciicwnaria froiulosa, found in tide 

 pools along rocky coasts on both sides of the North 

 Atlantic, is one that presents a particularly magnifi- 

 cent set of bushy tentacles when fully expanded. Along 

 the body of a Cucumaria, five lengthwise tracts of 

 short tube-feet show the five-parted symmetry so ob- 

 vious in most echinoderms. 



In Thyone, the whole body is studded with tube- 

 feet and curved into a broad U. Ordinarily these ani- 

 mals bury themselves in the bottom with only the 

 cloacal opening and the bushy tentacles exposed. If a 

 Thyone is dug out and then placed on the sea floor, 

 it usually needs three to four hours to work itself into 

 the hidden position again. 



Some other sea cucumbers with bushy tentacles 

 have a scale covering. Usually these animals rest on 

 a solelike area of the lower surface, and give the 

 general appearance of an armored slug with tentacles 

 instead of gills. They creep from place to place, and 

 can climb the vertical walls of a glass aquarium at 

 fair speed. Psoitis has tube-feet only around and un- 

 der the creeping sole, whereas Psolidiiiin extends 

 degenerate tube-feet that lack sucker tips through 

 holes in the body scales. 



Psoitis cmtarctictis carries as many as 22 young 

 along with it, holding to smooth areas of the creeping 

 sole. Cucumaria parva has been seen holding plant 

 material against its body, helping keep young in 

 place. Other species of these two genera have pockets 

 in the body wall, usually around the anterior end, in 

 which the eggs develop. 



These large sea cucumbers in a coral reef of the South 

 Pacific face the danger of being collected and pre- 

 pared for human food as "beche-de-mer" or "trepang." 

 (Great Barrier Reef. Fritz Goro: Life Magazine) 



Large tropical and subtropical sea cucumbers usu- 

 ally have twenty tentacles, but each of these feeding 

 organs has an expanded tip and cannot be withdrawn 

 into the body as is done by cucumbers with bushy ten- 

 tacles. Holotlmria is one genus of particularly inert 

 and sausage-like sea cucumbers, with no obvious 

 flattened surface to indicate a ventral side. Actinopyga 

 has a creeping sole, as has Stichopus. Both of these 

 live in exposed positions on mudflats, reaching rec- 

 ord lengths of 40 inches and a diameter of 8 inches. 

 Actinopyga differs from Stichopus in that the anus 

 opens into the cloaca through an armament of five 

 limy teeth. Stichopus lacks these teeth, but has the 

 ability to raise its body in waves of movement, like a 

 giant caterpillar walking, and shift the animal far 

 more rapidly than use of its tube-feet would permit. 



Close relatives of these cucumbers live in the great 

 depths of the ocean. There Bathyplotes appears to 

 drift well above the bottom for most of its life, sup- 

 ported by a float extending around the rim of its 

 creeping sole. Mesothuria intestinalis, a grayish white 

 animal often tinged with pink or violet, is sometimes 

 found also near the surface. It covers its body with 

 debris, as though to hide from enemies, and has been 

 found to begin adult life as a male, later transforming 

 into an egg-laying female. 



Molpadonias are sea cucumbers with a conspicu- 

 ous tail, often found buried in the bottom mud with 

 only the tail tip and cloacal opening exposed. These 

 animals lack tube-feet, or have them only around the 

 anus, perhaps used there in keeping the cloaca free 



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