13 



Whereas our Bermudian species, Stichopus moebii, eats mud, 

 or rather the calcareous sand of the coral rifs and monotonously 

 continues eating it day after day, this species shows a little 

 more complicated behavior. 



In its natural habitat this species lives in mud in shallow 

 places. This mud is of the darkest and richest kind, almost blue 

 in color and full of detritus. If one puts some specimens in an 

 aquarium the bottom of which is covered with this mud, one 

 can observe that after a little while part of the animals have 

 buried themselves in the mud and on dissection the gut will 

 be found full of this material. After some time however the 

 majority of the animals is found partly buried in the sand, but 

 with their ring of tree-like tentacles sticking out of the mud. 

 These tentacula arborescentia are in constant motion and a 

 closer study of their behavior reveals a most interesting game. 



Like nets these little arms move through the water in a fan- 

 like and slow movement, apparently for the purpose of fishing 

 small planktonts and debris out of the water. As soon as one 

 of these bumps against one of the tentacles, the organ slowly 

 bends downward and disappears into the mouth. 



Of the ten tentacles the two ventral ones appear to be very 

 much shorter. Shortly after one of the large tentacles has disap- 

 peared into the mouth, it comes back, and the small tentacles 

 now functionate as , f scratchers" and whipe the returning tentacle 

 off. Another tentacle again disappears and the same rhythmic 

 game goes on for hours and hours at a stretch. 



Has a Thyone once found a suitable place, it can stay there 

 for weeks and weeks, fishing in uninterrupted rhythm, once 

 about every 7 ! /2 minutes (Pearse 98)), a most interesting and 

 fascinating spectacle. Cucumaria planci according to Dohrn 32), 

 has preference for thick bushes of algae in which they hang 

 for months. 



From these observations it will be evident that Thyone is 

 by no means an exclusive mud-eater, and it can not astonish 

 us any more that, as we will see in chapter 19, the dried 

 contents of the stomach contain much more nitrogen pro gram 

 of substance than the mud in which the animals live. 



Many other Holothurians live only on mud or sand, i.e. on 

 the organic material contained in it. The importance of this 

 process, the amount of bottom material ,, worked through" by 

 Stichopus moebii, has been estimated by Crozier 18). 



Stichopus moebii. Semper, a very large species, such as are 

 eaten by the Chinese as ,,trepang", occurs in great abundance 

 in the Bermuda islands on the shallow littoral bottom. Its sits 

 on the sand and eats it by means of its 18^20 shovel-like 

 tentacula peltata. Crozier determines the amount of sand present 

 in the gut when it is filled completely. Then he observes how 

 many times a day the gut is filled. This is possible because 



