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Toad Crab

Hyas coarctatus

The toad crab is a distinctive and hardy crustacean found in mud, sand, and gravel habitats along the North Atlantic coasts. It is known for its large, spiny body and broad, flat claws, which it uses to feed on a wide range of organisms, including amphipods, marine worms, bivalves, sea urchins, small crabs, and even scavenging on dying or dead fish. Toad crabs are particularly adept at hiding among rocks, seaweed, or debris, where their mottled coloration helps them blend seamlessly into the environment.

Young toad crabs are known as decorators due to their unique behavior of attaching bits of algae, seaweed, or other debris to their carapace and walking legs, creating a form of natural camouflage. This helps protect them from predators by making them less noticeable. As they grow older, toad crabs undergo their terminal molt, and their carapaces often become encrusted with barnacles, tube-building worms, and bryozoans. These growths are not for camouflage but result from their larger size and the environments they inhabit.

Toad crabs are also notable for their reproductive habits. Females carry a mass of 1,500-8,000 fertilized eggs under their abdomen from April to August, although the eggs do not hatch until 9-11 months later. This slow reproduction cycle is a key aspect of their life history.

Fun Fact!

Young toad crabs use algae and debris to decorate their shells, improving their camouflage, while older individuals are often encrusted with barnacles and other organisms due to their size and final molt.

Habitat & Range

Toad crabs are found along the coasts of the North Atlantic, from Iceland and the Scandinavian peninsula to the Mediterranean Sea. They thrive in mud, sand, and gravel habitats, often hiding among rocks and debris.

Lifespan & Growth

Toad crabs can live up to 3 years, growing to about 10 cm in width. Small individuals use camouflage to blend in, while older crabs may carry encrustations on their carapace, marking the end of their molting process.

Role in Ecosystem

Toad crabs help recycle nutrients in marine ecosystems by scavenging dead organic matter and preying on smaller organisms. They are an essential part of the food chain, providing nourishment for a variety of marine predators.

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