CHAPTER XV 

 SOME LOWER ANIMALS 



A FEW of the lower animals should receive some attention 

 besides those already discussed. Spiders, crayfish, lobsters, 

 crabs, clams, oysters, snails, starfish, coral, sponges, and other 

 related forms make very interesting nature-study material. 



Most people probably think of Spiders as insects. Pupils 

 should be taught the chief distinctions between these two 

 classes. Spiders have eight legs, and their bodies are divided 

 into only two principal parts. The head and chest are not 

 distinct from each other, but the abdomen is marked off from 

 them. Spiders do not have compound eyes, but a variable 

 number of simple eyes. Furthermore, they have no wings. 

 Otherwise they closely resemble insects. Spiders have good 

 mouth-parts adapted for catching and eating insects. The 

 jaws or mandibles are especially large and terminate in sharp 

 fangs, through which a poison can be ejected into the victim 

 which kills or paralyzes it. This poison, however, is not 

 powerful enough to produce painful or dangerous results in 

 man, except in the case of the larger ground spiders, such as 

 the tarantulas, whose poisonous bite is painful, but not, as is 

 usually believed, fatal to man. The spider has a pair of 

 jointed palpi or feelers, which often resemble another pair of 

 legs. 



Spiders make good school-room studies. Have the children 



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