Marine Invertebrate Animals

Definition of the term invertebrate, as used in marine biology. Learn about invertebrates - where invertebrates live, what they look like, and examples of invertebrates.

What is a crustacean? Learn about crustaceans, who are arguably some of the most important marine life to humans.

Crustaceans marine invertebrate animals that are in the Phylum Arthropoda and Subphylum Crustacea. This group includes such commonly-known marine life such as crabs, lobsters, barnacles and shrimp. It also includes amphipods and isopods. Learn about characteristics of crustaceans, how crustaceans are classified, what they eat, how they...

Information about starfish, including the number of starfish species, images, starfish habitat, feeding and reproduction.

Nudibranchs are beautiful sea slugs in the Phylum Gastropoda. They are subjects of scientific study, and a source of fascination for ocean enthusiasts. Here you can learn more about nudibranchs.

Facts about nudibranchs - learn information on these fascinating sea slugs that live in all the world's oceans. What do nudibranchs eat? How do nudibranchs reproduce? Where can you see a nudibranch? Learn here.

Information about the Spanish shawl nudibranch (Flabellina iodinea), a brightly-colored nudibranch that lives in the Pacific Ocean.

Learn more about nudibranchs - colorful sea slugs that live around the world. Information about nudibranchs include what nudibranchs eat, where they live, how they reproduce and their relationship with humans.

Cephalopods are mollusks in the Class Cephalopoda, which includes octopuses, squid, cuttlefish and nautilus. These are ancient species that are thought to have originated about 500 million years ago. There are about 800 species of cephalopods in existence today.

Information about jellyfish. Learn facts about jellyfish, where jellyfish are found, how they feed and reproduce, and examples of jellyfish.

Information about the blue button jelly, a species of hydroid. Learn where to find blue button jellies, what they eat, and how they reproduce.

Information about the lion's mane jellyfish, a huge jellyfish with long tentacles. Learn what lion's mane jellyfish eat, where they live, and how they reproduce.

While the classification name, "Asteroidea," may not be familiar, the organisms it contains likely are. Asteroidea includes the sea stars, commonly called starfish. Starfish can be a range of sizes and colors, and are a wide-ranging marine invertebrate. Organisms in the Class Asteroidea have several arms (usually between 5 and 40) arranged...

There are about 1,800 species of sea stars, commonly known as starfish. Starfish are among the most easily-recognizable marine creatures, although they come in a variety of shapes, sizes and colors. Sea stars are classified in the Phylum Echinodermata, meaning they are related to sea urchins, sand dollars and sea cucumbers. See images of sea...

Facts about the brittle stars, basket stars and serpent stars, marine invertebrates that belong to the Class Ophiuroidea, the group of marine invertebrates that contains the brittle stars and basket stars. Learn where brittle stars and basket stars live, how they feed, and how they reproduce.

Lobsters are a delicacy, but are also an interesting animal in the wild. Learn about lobsters and gain answers to some frequently asked questions about this crustacean.

Lobsters are bright red on your plate, but they are usually a brownish-green in the wild. What happens between the sea and the dinner table to turn them bright red?

When you think of lobster, do you think of a bright red crustacean on your dinner plate, or a territorial creature roaming caves in the ocean? Despite their fame as a delicacy, lobsters also have fascinating lives. Learn more about this iconic marine creature here.

Many think of lobster as a bright red delicacy served up with a side of butter. But the American lobster (often called the Maine lobster), while a popular seafood, is also a fascinating animal with a complex life. Lobsters have been described as aggressive, territorial, and cannibalistic, but you may be surprised to know they've also been...

Want to know the sex of a lobster you've caught or are about to eat? Here's how to tell.

Coral reefs provide some of the most spectacular underwater scenery, and marine life biodiversity in the world. Here you can learn what coral is, how coral reefs form, and threats to coral reefs.

Sea stars (starfish) are beautiful animals that are a variety of colors, shapes and sizes, although all resemble a star. While some appear smooth, they all have spines covering their upper surface and a soft underside. If you gently turn over a live sea star, you'll see its tube feet wiggling back at you. These iconic marine animals are...

Echinoderms, or members of the Phylum Echinodermata, are some of the most easily-recognized marine invertebrates. The Phylum Echinodermata includes 4 classes: Stelleroidea (sea stars), Echinoidea (sea urchins and sand dollars), Holothuroidea (sea cucumbers) and Crinoidea (sea lilies and feather stars.) They are a diverse group of organisms,...

Sea stars, or starfish, are star-shaped animals that are a variety of shapes, sizes and colors. You might be most familiar with sea stars that live in tide pools in the intertidal zone, but some sea stars live in deep water. Here you'll learn about sea star reproduction, classification, feeding and more.

You may have eaten a scallop, but do you know exactly what you were eating? You also may have found a brightly-colored scallop shell on the beach. Here you can learn more about this popular seafood - where scallops live, how big they get and how they feed and reproduce.

Coral reefs are centers of biodiversity, where you'll find many types of fish,invertebrates and other marine life. Coral reefs are composed of animals called stony corals. Corals are made up of tiny organisms called polyps.

Learn how pearls form, including species that make pearls.

Learn about the Sally lightfoot crab (Grapsus grapsus), a colorful crab found in warm waters of the Atlantic and Pacific Oceans.

The green crab (Carcinus maenas) is commonly found in New England tide pools and along the East Coast of the United States from Delaware to Nova Scotia, but this species is not native to the area. This now-abundant species is thought to have been introduced into U.S. waters by the ballast water on ships coming from Europe.

Marine life profile of the Chinese mitten crab (Eriocheir sinensis). The Chinese mitten crab is native to East Asia and has funny-looking, hairy claws. The Chinese mitten crab is considered one of the top 100 world's worst invasive species.

Jellyfish are soft-bodied invertebrate animals. Learn about the jellyfish's life cycle, feeding, and distribution.

This animals is one of the world's largest gastropods. Learn about how this sea hare gets its coloration, what it eats and where it lives.

mollusks, molluscs, phylum mollusca, bivalves, gastropods, cephalopods

Conchs are a type of sea snail, and are also a popular seafood in some areas. The term 'conch' (pronounced "konk") is used to describe over 60 species of sea snails which have a medium- to large-sized shell. In many species, the shell is elaborate and colorful. Probably the most well-known species is the queen conch, which is the image that might come to mind of a sea shell. This shell is often sold as a souvenir, and it's said you can hear the sea if you put a conch shell to your ear.

The Class Gastropoda includes snails, slugs, limpets and sea hairs - all animals referred to as 'gastropods.' Gastropods are mollusks, and a extremely diverse group that includes over 40,000 species. Envision a sea shell, and you're thinking about a gastropod, although this class contains many shell-less animals as well. Examples of gastropods...

The Order Mesogastropoda is an order of snails, and includes sea snails, freshwater snails, and land snails. There are about 30,000 species in...

Gastropods are animals in the Class Gastropoda - the group of organisms that includes snails, slugs, limpets and sea hares. There are over 40,000...

Profile of the crystal jelly - Aequorea victoria - a jellyfish species known for its luminous green fluorescent protein (GFP). Cells from the crystal jelly might be important in early detection of cancer in humans.

Information about the cnidaria - the phylum that contains corals, jellyfish, sea anemones, sea pens and hydras. Learn about cnidaria facts, life cycles, where cnidaria are found and examples of cnidarians.

Information about stony corals, the corals that form coral reefs. Stony corals, also called hard corals (as opposed to soft corals, like sea fans), are the reef-builders of the coral world. Learn more about stony corals - what they look like, how many species there are, and where they live.

Facts about the Christmas Tree Worm.

Do starfish have eyes? Information about starfish (sea star) eyes.

Stiff pen shell marine life profile - facts about the stiff pen shell (Atrina rigida), including pen shell classification, feeding, habitat, distribution, reproduction and human uses.

Information about the Class Echinoidea, including classification, feeding, habitat, reproduction and human uses.

Crustaceans include commonly-known marine life such as crabs, lobsters, barnacles and shrimp. These animals are in the Phylum Arthropoda and Subphylum Crustacea. Here you'll find the definition of crustacean and learn more about crustaceans.

Information about the green sea urchin, including the sea urchin's classification, feeding, habitat, reproduction and human uses.

Information about sponges, animals in the phylum Porifera.