Field guide · Species directory
Crustaceans
Atlantic Blue Crab
Callinectes sapidus
A swimming crab with bright blue claws and a sturdy diamond-shaped shell. The Chesapeake Bay blue crab fishery is one of the most economical…
Acorn Barnacle
Semibalanus balanoides
A sessile crustacean (yes — barnacles are crustaceans, not mollusks) that builds a calcified plate-armor home cemented to rocks. Tiny feathe…
Asian Shore Crab (invasive)
Hemigrapsus sanguineus
A small invasive crab introduced via ballast water. Now extremely abundant along eastern US coastline. Displacing native crabs.
Atlantic Hermit Crab
Pagurus longicarpus
A small marine crustacean that protects its soft abdomen by occupying empty snail shells, switching shells as it grows. Common on East Coast…
Atlantic Stone Crab
Menippe mercenaria
Stout-bodied crab with massive claws. Major commercial fishery; claws regenerate after harvest, allowing sustainable fishing.
Common Crayfish (Northern)
Faxonius virilis
A medium-sized lobster-like freshwater crustacean — a keystone food source for many fish, birds, and mammals. Native populations support ent…
Crayfish (Northern/Eastern)
Faxonius rusticus
A medium-sized crayfish native to the Ohio River drainage. Now invasive in many other US waterways.
Dungeness Crab
Cancer magister
A medium-large Pacific crab. Major commercial and recreational fishery on Pacific coast.
Mantis Shrimp (Caribbean)
Squilla empusa
A burrowing crustacean with the most complex eyes in the animal kingdom and the fastest punch in nature — striking with the acceleration of …
Spider Crab
Libinia emarginata
A medium-sized spider-like crab.
Stone Crab (Florida)
Menippe mercenaria
Florida stone crab famous for sustainable claw harvesting.
Zebra Mussel (invasive)
Dreissena polymorpha
A small invasive mussel introduced via ballast water from European ships. Devastating to native mussels and water quality systems.
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