Page 13 - One Million Things: Animal Life - The Incredible Visual Guide

5 MOLLUSCA 6 ECHINODERMATA 7 CHORDATA
This group of soft-bodied animals Unlike other animals, the echinoderms, The majority of chordates are vertebrates,
includes many that are protected by shells, or “spiny-skinned animals,” have a body which include the largest animals. They have a
such as slow-moving snails, whelks, and divided into five parts arranged like the backbone that forms part of an internal, flexible
limpets, as well as bivalves (those with a spokes of a wheel around a central point, skeleton that supports the body and is moved by
shell in two hinged halves), such as mussels, and a supportive skeleton made of hard attached muscles. They also have four limbs and a
that barely move at all. By contrast, the plates lying just beneath the skin. The highly developed nervous system and sense
cephalopod branch of the phylum includes phylum includes starfish, brittlestars, organs. Vertebrates include birds, mammals,
mollusks such as squid, cuttlefish, and sea urchins, and sea cucumbers, all of reptiles, amphibians, and the various types of
octopuses that are intelligent and can which, as some of their names suggest, fish. Chordates that are not vertebrates include
shoot rapidly through water. live in the sea. sea squirts and lancelets.

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