Understanding Seafood Classifications

Aquatic animals with bony interior skeletons and fins

Take in oxygen through gills

Fish eggs, called caviar when processed and salted, are also considered seafood

Round fish: red snapper

Flat fish: flounder

Shellfish

Crustaceans

Aquatic animals with shells instead of skeletons

Take in oxygen in various ways

Can be further divided into two groups:

Have complex segmented exterior shells and legs

Examples: lobsters, shrimp, and crabs

Lobster © Valerie Loiseleux/iStockphoto.

Blue crabs

Shrimp © iStockphoto.

Mollusks

Have simple shell structures (or no shell) and no legs

Can be further divided into three groups:

Cherrystone clams

Blue mussels

St. James River oysters

Scallop in shell © Georg Hergenhan/iStockphoto.

Abalone Courtesy SFB (SeaFood Business).

1. Bivalves: Shellfish with hinged two-section exterior shells

   Examples: clams, oysters, mussels, scallops

2. Univalves: Similar to bivalves, but have only one exterior shell section

   Example: abalone

3. Cephalopods [SEF-ah-low-pods]: Mollusks with tentacles and a defined head

Some, such as squid and cuttlefish, have interior shell-like structures.

Octopus, on the other hand, have no interior shells

Example: Squid

Squid