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Biology: THE ANIMAL KINGDOM: Invertebrates

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Biology: THE ANIMAL KINGDOM: Invertebrates

Any organism that does not have a backbone (spinal column) and is made up of more than one cell is called an invertebrate. Invertebrates make up 95 percent of all animal species; of the 20 phyla, the two largest are Arthropoda and Mollusca. Some of the more well-known invertebrate phyla are discussed below (in alphabetical order).

Phylum: Annelida

Annelids, or segmented worms, include earthworms, leeches, and marine worms. These worms have soft bodies, are symmetrical, and can be anywhere from 1/32 inch (0.5 millimeter) to 10 feet (3 meters) in length. Earthworms are seen on sidewalks and driveways during periods of heavy rain ...

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