Invertebrates

Invertebrates are the most diverse and numerous group of animals on Earth. There are more than 140,000 invertebrates in the United States—a number that is growing as researchers identify more and more species. Of the invertebrates in the U.S., approximately 200 are on the endangered species list.

An invertebrate is a cold-blooded animal with no backbone. Invertebrates can live on land—like insects, spiders, and worms—or in water. Marine invertebrates include crustaceans (such as crabs and lobsters), mollusks (such as squids and clams), and coral.