From crabs to octopuses, clams to marine worms, invertebrates play a significant role in ocean ecosystems. Many are important prey for fish, marine mammals, and humans. Others, such as corals and oysters, create essential habitat for marine species.

NOAA Fisheries is responsible for the sustainable management of many species of invertebrates—including white shrimp, Alaska snow crab, and Quahog clam—commonly harvested for human consumption. We are also responsible for protecting invertebrate species listed under the Endangered Species Act such as white abalone and elkhorn coral.

Invertebrates are the most diverse group of animals in the ocean. Some common marine invertebrates include mollusks, crustaceans, and corals.

Mollusks are a category of invertebrates with over 50,000 known species. They are soft-bodied animals that may have a hard external shell (formed by secreting calcium carbonate), a hard internal shell, or no shell at all. Mollusks include abalone, conch, oysters, and clams, as well as octopus and squid.

Crustaceans are a subcategory of invertebrates closely related to insects and spiders. They typically have a body covered with a hard shell or crust. Crustaceans include shrimp, krill, lobsters, and crabs.

Corals are known as colonial organisms because many individual creatures live and grow while connected to each other. The tiny, individual organisms that make up large coral colonies are called coral polyps. Stony, shallow-water corals—the kind that build reef habitat—are one type of coral. There are also soft corals and deep sea corals that live in dark, cold waters.

Learn more about corals

Species News

Penaeid shrimp, which is a white, semi-transparent shrimp are one of the most valued species in the Gulf of Mexico. Credit: NOAA Fisheries Penaeid shrimp (white shrimp pictured here) are one of the most valued species in the Gulf of Mexico. Credit: NOAA Fisheries
A color image taken in a well-lit laboratory counter. A ruler is laid horizontally in the center of the image in the background. Three larger scallops are laid side-by-side along the top edge of the ruler and three smaller scallops are laid side-by-side along the lower edge. Each scallop has distinct, and different, striped patterns on the top shells. Atlantic sea scallops collected during the 2022 survey show the variety in coloration for this species. Credit: NOAA Fisheries/Christine Kircun
Coral recruit A tiny coral has settled on crustose coralline algae after a mass mortality event. This is a great sign for reef recovery! Credit: NOAA Fisheries/Brittany Huntington
Fishermen out for a trip in Florida Keys National Marine Sanctuary Fishermen out for a trip in Florida Keys National Marine Sanctuary. Credit: Nick Zachar/NOAA


Peer-Reviewed Research

Incorporating Spatial Heterogeneity and Environmental Impacts Into Stock-Recruitment Relationships for Gulf of Maine Lobster

A study of how spatial diversity and environmental effects can be incorporated into functional…

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Summary of ocean ecosystem indicators used to characterize juvenile marine salmon survival in the Northern California Current.

Ocean Acidification Research in the Pacific Northwest

About a quarter of the carbon dioxide released into the atmosphere by burning fossil fuels is absorbed into the ocean. There it causes a chemical change resulting in ocean acidification. This chemical change has the potential to profoundly alter marine…

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The green crab is invading from the west coast and has recently reached Alaska.


Understanding Sustainable Seafood

Well-managed wild-capture fisheries and environmentally responsible marine aquaculture play an increasingly important role in our food supply, our health, and the environment.