CLASSIFICATION OF ANIMALS 



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The following are the principal classes of Protozoa, examples of which we may have seen or 



read about : — 



Class I. Rhizop'oda (root-footed). Having no fixed form, with pseudopodia. Either naked 

 as Amoeba or building limy (Foraminifera) or glasslike skeletons (Radiolaria) . 



Class II. Mastigoph'ora. They move by means of long whiplash threads of protoplasm, called 

 fiagella. Examples are Euglena and Monosiga. 



Class III. Infuso'ria (in infusions). Usually active ciliated Protozoa. Examples, Parame- 

 cium, Vorticella. 



Class IV. Sporozo'a (spore animals). Parasitic and usually non-active. Example, Plas- 

 modium malarioe. 



II. Porif' era (Lat. porus, pore ; ferre, bear) or Sponges. — The body con- 

 tains many pores through which water bearing food particles enters. They 

 are classed according to the skeletons they possess into limy, glasslike, and 



Grantia 



Venus's flower basket 

 Sponges. 



Bath sponge 



horny fiber sponges. The last named are the sponges of commerce. Most 

 sponges live in salt water; they are never free swimming. There are about 

 2500 species named. 



The Grantia seen along our northeastern 

 Exam- 



The following is their classification : — 

 Class I. Calca'rea, having limy spicules in the body. 



coast is an example. 

 Class II. Hexactinel'lida. Sponges having glasslike spicules, arranged on three axes. 



pie, Venus's flower basket. 

 Class III. Demospon'gice. Sponges with glasslike spicules, not arranged on three axes, or 



with skeleton of horny fiber, the latter type represented by the bath sponge. 



III. Coelentera'ta (Gr. koilos, hollow; enteron, intestine). — The hydra 

 and its salt-water allies, the jellyfish, hydroids, and corals, belong to this 

 group. They are animals in which the real body cavity is lacking, the simplest 

 ones being little more than bags. They have only two cell layers in the body 

 wall. These animals are provided with peculiar cells called " nettling cells," by 

 means of which they defend themselves from attack and kill their prey. There 

 are about 4500 known species. 



There are three classes of the Coelenterata, or Coelen'terates. 



Class I. Hydrozo'a. Simple animals as hydra, or colonial in habit as the hydroids. They 

 produce new individuals by budding, and the eggs and sperms are usually produced in a free- 

 swimming jellyfish, which buds off from the original colony. This is an example of alterna- 

 tion of generations. Examples : Hydra, Obe'lia, and many other hydroids. 



Class II. Scjjx>ho?f/a. Marine jellyfish, mostly of large size. 'Example, Aurelia. 



