STAR-FISHES, SEA-URCHINS, ETC. 



353 



de-mer soup is held in high favour, and its more 

 extensive introduction onthe menu-cards of Western 

 civilisation may be only a question of time. 



Many species of sea-cucumbers inhabit British 

 seas, but none possess that density of tissue which 

 is essential for their economic conservation ; the 

 majority, moreover, are of comparatively small size, 

 some few inches long only when fully extended, 

 whereas the commercially valuable tropical ones may 

 measure as much as from 2 to 3 feet. The mode of 

 feeding of sea-cucumbers is somewhat interesting; 

 the smaller species, with much-branching tentacles, 

 generally affix themselves by their tube-feet to 

 some object, and, extending their tentacles in all 

 directions, utilise them, like those of a sea- 

 anemone, for seizing any minute and suitable prey 

 which may strike against them. The microscopic 

 organisms on which they chiefly feed abound in 

 the waters they inhabit, and one after the other, 

 the branched tentacles having effected a capture, 

 are gathered together and tucked bodily into the 

 creature's central mouth and apparently half-way 

 down its throat. The larger coral-frequenting 

 species are provided mostly with mop-shaped 

 tentacles. They crawl about leisurely in search of 

 their food, mopping over the ground, and gathering 

 up in their tentacles the minute shells and other 

 organisms on which they subsist, which are col- 

 lectively thrust with an indrawn tentacle into the 



tj W. Savill,-KM, F.Z.S.~\ 



BRANCHING-ARMED 



[Milford- en-Sta 



BRITTLE-STAR 



The specimen is attached to a brilliant scarlet sponge 



>l> h; If. S<ivtll<-K,nl, F.Z.S. 



SEA-CUCUMBERS, SOME WITH 

 EXTENDED TENTACLES 



West Australian species "whose colours are bright pink and yclloiv 



throat. In some of the lower forms the tube- 

 feet have disappeared, the integument is thin 

 and semi-transparent, and the worm-like animal 

 crawls about by means of its skin-spinules, 

 which take the form of anchors or grappling- 

 hooks. In an opposite direction they may 

 develop a supplementary covering of dermal 

 plates and a more rigid integument, which 

 indicate their nearer relationship with sea- 

 urchins. 



The majority of sea-urchins and star- 

 fishes pass through a series of interesting 

 metamorphoses before arriving at the adult 

 state. The larval phases in these instances 

 are free-swimming organisms, having arm-like 

 processes, strengthened by calcareous rods 

 that have been likened in contour to a clock- 

 stand. A small spherical central area, like a 

 clock in its case, representing the stomach of 

 the larva, develops spicules around it, and 

 becomes the body of the urchin, the other 



