KEY TO ANIMAL PHYLA 



1(2) Animals consisting of a single cell, or of a colony of 

 similar cells, or of a mass of protoplasm with a number 

 of nuclei irregularly arranged, always lack tissues; 

 almost always microscopic. Fresh-water, or marine 

 or moist situations. Phylum Protozoa, p. 6 



2(1) Animals consisting of many cells arranged in tissues; 

 the Metazoa. 3 



3(5, 9) Body without definite planes of symmetry or radially 

 symmetrical; never spirally coiled. 4 



4 Sponges with the body more or less indefinite in form; 

 a sessile crust or mass with a rough, spiny wall pierced 

 by numerous microscopic pores and by one or more 

 large openings. Tentacles absent. 



Phylum Porifera, p. 10 



5(3, 9) Body radially symmetrical; wall not pierced by pores, 

 a closable mouth present. 6 



6(7, 8) Jelly-like animals with eight rows of ciliated swimming 

 plates. Tentacles, if present, without nematocysts. 

 Marine forms. (Pratt, 150.) Phylum Ctenophora 



7(6, 8) Body without eight rows of ciliated plates, tentacles 

 present bearing nematocysts. No anus present. 

 Sessile (hydroids and sea anemones) or free swimming 

 (jellyfish) . If sessile, may be either solitary or colonial. 

 Parts arranged in fours or sixes or indefinite. 



. Phylum Coelenterata, p. 11 



8(6, 7) Parts of body usually in fives; outer covering spiny or 

 leathery; anus usually present. Tentacles usually 

 absent and never bear nematocysts. Starfish, sea 

 urchins, sea cucumbers. All marine. 



Phylum Echinoderma, p. 18 



