Common name: common hermit crab

General information

The Common Hermit Crab, Pagurus bernhardus, is a species of hermit crab that is widely found in the North Atlantic Ocean and parts of the North Sea. It is known for its distinctive behavior of living in discarded snail shells to protect its soft abdomen. As the crab grows, it must find larger shells and often engages in shell fights to obtain a new home.

Hermit crabs are fascinating creatures for the marine aquarium due to their scavenging habits, which help keep the tank clean by consuming detritus, uneaten food, and decomposing organic matter.

Care

Pagurus bernhardus requires a variety of appropriately-sized empty shells in the aquarium to allow for growth and shell changes. They thrive in a well-established tank with plenty of live rock and a sandy substrate that mimics their natural environment. Stable water quality and parameters are crucial for their well-being.

Reproduction

In the wild, Common Hermit Crabs breed during the warmer months. The female carries fertilized eggs on her abdomen until they hatch into free-swimming larvae. In captivity, breeding is less common, but with optimal conditions, it is possible to observe larval stages.

Symbiosis

While not as pronounced as in some other species, hermit crabs can engage in symbiotic relationships with sea anemones. In some cases, hermit crabs will carry small anemones on their shells, which provide additional protection through their stinging cells, while the anemones benefit from increased mobility and access to food.

Habitat

Pagurus bernhardus is typically found in shallow waters, often in rocky areas, where there is an abundance of empty snail shells to occupy. They can also be found in deeper waters up to 140 meters.