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Animals with Jointed Legs — The 

 Arthropods 



This is a very extensive phylum including such commonly known 

 animals as crayfish, crabs, shrimp, spiders, scorpions, centipedes, and 

 insects. 



We commonly think of the vertebrate animals as being the most suc- 

 cessful and dominant of all the animal groups, yet, if the Arthropoda had 

 the power of reasoning and could communicate their thoughts, they 

 would probably claim this distinction. Furthermore, they would have 

 very good arguments in support of their claim. They could show that 

 over half of the species of animals that have been named and classified 

 are arthropods, so, if success is measured in the diversity of types within 

 the phylum, we could not dispute their claim. They could point out 

 that arthropods are found everywhere that vertebrate animals are found 

 and in many places where vertebrates cannot live. They may be found 

 at the equator and in the arctic regions ; they may be found flying high 

 in the air and in the depths of the ocean ; they inhabit the humid jungles 

 and the dry sandy deserts. No extreme of environment seems to dis- 

 courage them. They are the only animals that have been able to adapt 

 themselves to the highly concentrated salt water of inland lakes having 

 no outlet to the ocean, such as the Great Salt Lake and the Dead Sea. 

 The Great Salt Lake contains about 27 per cent salt and is so dense that 

 a person's body floats on it like a cork, yet it contains many little shrimp 

 which spend their entire existence in this concentrated solution. There- 

 fore, when the point of adaptation to environment is brought up, we must 

 concede the advantage to the arthropods. Finally, it could be stated that 

 there is no other group of animals on the earth so well armed for offense 

 and defense. It is true that man, as one of the vertebrates, has been 

 able to forge steel into terrible weapons of destruction, but the arthropods 

 have forged their weapons from their own bodies and they are highly 

 efficient and always ready for use. Of course, there would be some 

 arguments in favor of the vertebrates, such as larger size and greater 

 development of the brain and its functions. In the final analysis, how- 

 ever, we would have to conclude that the arthropods are at least the equal 



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