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This crab is crawling along the shore looking for food.
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Windows Original, adapted from Corel Photography

Crabs

Crabs are in the Crustacean phylum, which means they have hard exoskeletons that protect the soft body underneath. They also have sharp claws for battling predators and grabbing prey. There are many species of crabs, and they come in all shapes and sizes. Most crabs live in coral or rocky reefs, but others prefer the sandy shores. Crabs are usually not fussy eaters, but they prefer small invertebrates and plankton.

One class of crabs is called Hermit Crab. These special little animals live inside shells, which they pull along on their backs. In case of a threat, they can crawl inside for protection. The Thin-clawed Hermit Crab is about 7 inches long, and has bright blue eyes with an orange body. It looks more like an alien than a crab!

Others, like the Smooth Shore Crab, are only a few inches long. They don't have a shell with them, so spotting one in the day time is almost impossible. The Smooth Shore Crab is rather plain, but some have very unusual designs. The Mottled Shore Crab has a yellow-brown shell, with bright white grooves. This little crab is less than a half-inch long, but it still looks scary!

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA