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Sea urchins



Category: Invertebrates



These small, spiny, globular animals inhabit all the oceans of the world and can survive in shallow intertidal zones, 5000 meter deep abyssal zones, and nearly anything in between. They move slowly about on their hydraulic tube feet, feeding mostly on algae. Sea urchins are able to adjust their metabolisms to the level of nutrition available in their environment. Many species of animals, including humans, hunt and eat sea urchins. Their internal organs are protected by a hard shell called a “test”, to which their spines are attached via rounded turbercles. The spines serve as protection and are toxic in some species.



Data & Facts

Scientific Classification
Kingdom - Animalia
Phylum - Echinodermata
Class - Echinoidea

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Interesting Animal Facts

The world’s first Animals

Invertebrates were the first animals to evolve. While their soft bodies left precious few records behind, there are fossils of sponge-like animals that are 665 million years old, as well as traces of tracks and burros from worm-like animals going back 1 billion years. By comparison, the earliest birds appeared only 150 million years ago! And not only were invertebrates first, they are the most plentiful of animals - it is estimated that 97% of all animals living on the Earth today are invertebrates, with several groups containing more species than all vertebrates combined!

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