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TEXT-BOOK OF ZOOLOGY 



G. Organs of Nutrition. 



The star-fish is a predaceous creature 

 of insatiable appetite. On account of its 

 slow movements, however, it can only 

 possess itself of sessile or very slow- 

 moving animals. Hence its chief food 

 consists of lamellibranchs and gastropod 

 molluscs, and it is therefore regularly 

 met with on oyster and mussel banks. 

 It seizes its prey with its extended 

 pedicels and pliant arms, pressing its 

 toothless mouth against the shell-open- 

 ing of the mollusc. The latter naturally 

 closes its shell as tightly as possible, or 

 withdraws into it as far as it can. But 

 all is of no avail : after a brief time the 

 assailant has overcome its resistance, 

 probably by means of a poisonous secre- 

 tion which stupefies or kills its victim. 

 Into the gaping shell of the bivalve or 





ECHINODERMS (AND TUBICOLOTJS ANNELIDS) IN THE AQUARIUM. 



K.S., Common Star -Fish creeping up glass side of aquarium ; s.S., the same species embracing 

 and sucking out a gastropod mollusc ; Si., Common Sea-Urchin adhering to glass side ; 

 Sw., a Sea-Cucumber (Holothuria tubulosa) ; Sch., a Sand-Star (ophiurid) ; R., several 

 Tubicolous Worms three with their branchiae extended above the aperture of the tube ; 

 upon the middle one a Feather-Star (H.) has become firmly entwined, while on the right 

 are shown four larval stages of the Feather-Star (J.H.), of which the two larger ones are 

 slightly magnified. 



