Great spider crab

Language English

Onglets

Description

Distinguishing features

The great spider crab is distinguished by its carapace, which extends into a pointed tip, and by its long, thin legs, which make it look something like a spider. Reddish brown in color, the shell is often covered with algae, sponges or organisms that attach themselves to it, providing the crab with valuable camouflage on the seabed.

Its body reaches a length of 6 to 10 cm, while the legs can reach as much as 15 cm.

Reproduction

Great spider crabs reproduce in the spring, principally between February and April. The male chooses a female and carries her until she’s ready to mate, even if she has yet to molt – which is unusual in crustaceans.

Mating happens through the transfer of sperm via the male’s abdominal legs. The females then carry the eggs under her abdomen for several months. When these hatch, the larvae enter a planktonic phase that lasts two to three months, during which they drift in water at varying depth, which ensures the spread of the species.

After their metamorphosis, the young crabs settle on the seabed. They reach sexual maturity in two or three years, depending on the conditions of their environment.

Diet

An opportunistic omnivore, the great spider crab feeds on small invertebrates like mollusks, worms and echinoderms as well as algae and decomposing organic matter. It plays an important role in the recycling of matter on the seabed.

Predators

The great spider crab’s main predators are fish, seabirds and other crustaceans. Some groundfish like cod and halibut occasionally consume adult crabs, but their camouflage and their tendency to hide behind rocks are effective protection.

The great spider crab is especially vulnerable at molting time. At one stage of the process, its shell softens and it loses its defense against predators.

Habitat

The great spider crab lives mostly in salt water, from the low tide line to depths of about 50 metres.

It prefers gravel or rock substrates, which provide it with both camouflage and food. This species is particularly abundant in the temperate or cold areas of the North Atlantic, where the water temperature ranges from -1 to 15 degrees Celsius.

Ecology, behaviour

This crabs plays an important role in the marine ecosystem by recycling organic matter contained in the dead plants and animals it eats.

Although this crab is edible, it is not a key species for commercial fishing, its flesh being less abundant than that of the snow crab.

It is often caught accidentally, as bycatch in traps or nets intended for other species. It is nevertheless consumed or used as bait in certain northern regions. In scientific research it is studied to measure the effects of ocean warming on benthic species (those living on the ocean floor) in cold waters.

French name

Crabe araignée

Scientific name

Hyas araneus

Phylum

Arthropoda

Class

Malacostraca (crustaceans and one subphylum)

Order

Decapoda

Family

Oregoniidae

Size

Length: up to 10 cm; width (without claws): up to 6.4 cm

Status

Common species

At the Biodôme

The great spider crab inhabits the rocky coastline and the column in the underwater view in the Gulf of St. Lawrence ecosystem. It busies itself delving into every nook and cranny of its habitat in search of scraps of food that have sunk to the bottom. Its well-covered shell camouflages it and can make it difficult to spot.

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