Grand Bernard-l'ermite

Overview

The Dardanus arrosor, commonly known as the Mediterranean hermit crab or striated hermit crab, is a relatively large species of hermit crab found in various marine environments. It is widely recognized for its symbiotic relationship with sea anemones, which it carries on its shell for mutual protection.

Appearance

This crab is characterized by a bright red to orange carapace and robust, relatively short eyestalks that feature distinct red and white stripes with bluish eyes. Its claws are unequal in size, with the left claw being notably larger and more powerful than the right; both are covered in hair-like spines and warty tubercles. The tips of the claws are typically black or yellowish.

Distribution & habitat

Dardanus arrosor has an extensive distribution, spanning the Mediterranean Sea, the Atlantic Ocean, the Red Sea, and parts of the Indo-Pacific. It inhabits the continental shelf, favoring soft or mixed substrates such as sand, mud, and rocky bottoms. While it can be found in shallow waters, it is more commonly encountered at greater depths.

Biology & behavior

This species is primarily nocturnal, emerging at night to forage. It is well-known for its symbiotic association with the sea anemone Calliactis parasitica. The crab actively places these anemones on its host shell, providing the anemones with mobility and access to food, while the anemones offer the crab protection from predators, such as octopuses. As the crab grows and moves into larger shells, it carefully transfers its anemone partners to the new home. Reproduction typically occurs during the summer months, specifically between July and August.

Feeding

As a scavenger, this hermit crab plays a vital role in marine ecosystems by cleaning the seabed of organic debris. Its diet consists of carrion, small invertebrates, and algae.