Field Guide - Snow Crab
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Snow Crab
Chionocetes opilio
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Family: Oregoniidae
Genus: Chionocetes
Species: opilio
Description: In Alaska, the majority of snow crabs are found in the Eastern Bering Sea but they have a range extending up into the Chuckchi and Beaufort Seas. The size of snow crabs varies with water temperature (i.e., smaller in the colder northern waters and larger in the southern Bering Sea which is where males are commercially harvested).
Population status: Their populations crashed in the late 1990’s, forcing fisheries to reduce their catch limits. Presently, the number of commercially harvested snow crab in the Eastern Bering Sea is well above target populations and is considered a sustainably harvested crab.
General characteristics: Brownish to a light brick red in color on their backs and golden off-white on their undersides. Snow crabs are easily mistaken for tanner crabs, but snow crab have green eyes and ‘O’ shaped mouth parts, and tanners have red eyes and ‘M’ shaped mouth parts. Snow crabs are usually smaller than tanner crabs, but there is a wide range of sizes for both species of crabs.
Female defining traits: Females are significantly smaller than males and average 5.3– 9.5 cm for carapace width with 38 cm leg spans. Female abdominal flaps are circular and cover their entire undersides, providing an area to store eggs and sperm.
Male defining traits: Males are much larger than females and average 6.9–16.5 cm for carapace width with 90 cm leg spans. Abdominal flaps are triangular in shape and cover much less of their undersides than females.
Juvenile defining traits: Female juvenile snow crabs have circular abdominal flaps that cover only about 2/3 of their undersides and male juveniles have smaller claws than adults.
Diet in the wild: Young snow crabs eat plankton while older snow crabs eat worms, snails, crustaceans, sea stars, shrimp, mollusks, and fish.
Reproductive cycle: Females are sexually mature at age 4– 6 years, male and female pairs stay close together, mating in shallow waters in March-May. The female carries up to 160,000 fertilized eggs for 1– 2 years until they hatch in April-May.
Predators in the wild: Fish, skates, seals, sea otters, octopus, and eels. Also, a parasitic algae causes Bitter Crab disease which makes the crab taste bitter, and although it is not harmful to humans, it is fatal to the crab.
Similar species: Triangle tanner crab, tanner crab or bairdi, benzei-zuwai crab, and grooved tanner crab.
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Related Links & Sources
Scientists Scrutinize Bitter Crab Syndrome