Fauna
Invertebrate

Atlantic Blue Crab

Callinectes sapidus

Also known as Blue Crab, Maryland Blue Crab, Chesapeake Blue Crab

Atlantic blue crabs are fierce, highly active swimmers recognizable by their bright blue claws and paddle-shaped rear legs. Females undergo a dramatic physiological transformation before mating, developing rounded bellies and bright red claw tips. Crucial to coastal food webs, these crustaceans serve as both industrious scavengers and vital prey for fish, birds, and marine mammals.

CrustaceanMarineSwimmer
Atlantic Blue Crab reference1 / 7
Wikimedia Commons / CC BY-SA 3.0 · cc-by-sa
—observations
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Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preyHard Clams, Eastern Oysters, Small Fish
Predators
  • Striped Bass
  • Red Drum
  • Herring Gulls
ThreatsOverfishing, water pollution, habitat loss, oxygen-depleted dead zones
HabitatsEstuaries, coastal bays, salt marshes, shallow ocean waters
Life span3–8 years
Classification
  1. OrderDecapoda
  2. FamilyPortunidae
  3. GenusCallinectes
  4. SpeciesCallinectes sapidus
Range & activity
Range data is not available yet.
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Pincers are strong and sharp; handle with care behind the rear swimming legs.
Why it is dangerous
Powerful claw muscles combined with sharp pincer tips can inflict deep cuts and painful puncture wounds.
How to recognize a risky encounter
Look for an olive-green shell, bright blue legs, and prominent side spines framing the carapace.
What to do
Never grab near the front or side spines; pick up strictly from behind the rear swimming legs.
Responsible observation
  • Safe handling: Grasp firmly from the very back edge of the carapace or the bases of the rear paddle legs.
  • Observe behavior: Look for paddle-shaped rear legs used to swim swiftly sideways or backward through water.
  • Determine sex: Check the belly apron, which is T-shaped in males, triangular in immatures, and rounded in mature females.
Related species
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