ECHINODERMATA 



141 



Economic Importance of the Echinodermata 



Class 

 Asteroidea, 



Echinoidea. 

 Holothuroldea. 



Negative 

 Attack oysters and clams, open- 

 ing shells and devouring the 

 soft parts. 



Positive 



Fertilizer. 



Eggs used as food. 



Experimental embryology. 



Roe of sea urchins are eaten. 



Spines are used as slate pencils. 



Several species of sea cucum- 

 bers are utilized as food by 

 the Chinese under the names 

 of trepang or beche-de-mer. 



References on Echinodermata 



Cole, L. J. 1913. Direction of locomotion in the starfish, Asterias 

 forbesii. J. Exp. Zoo!., vol. 14. 



Gemmill, J. F. 1 91 2. The locomotor functions of the lantern in Echi- 

 nus, with observations on other allied activities. Proc. Roy. Soc. 

 Lond., Ser. B, vol. 85. 



Kindred, J. E. 1924. The cellular elements in the perivisceral fluid 

 of echinoderms. Biol. Bull., vol. 46, pp. 228-251. 



Paine, V. L. 1926. Adhesion of the tube feet in starfish. J. Exp. 

 ZooL, vol. 46, pp. 361-366. 



