Pagurus bernhardus is the common marine hermit crab of Europe's Atlantic coasts. It is sometimes referred to as the common hermit crab or soldier crab. Its carapace reaches 3.5 centimetres (1.4 in) long, and is found in both rocky and sandy areas, from the Arctic waters of Iceland, Svalbard and Russia as far south as southern Portugal, but its range does not extend as far as the Mediterranean Sea. It can be found in pools on the upper shore and at the mean tide level down to a depth of approximately 140 metres (460 ft), with smaller specimens generally found in rock pools around the middle shore and lower shore regions, with larger individuals at depth. P. bernhardus is an omnivorous detritivore that opportunistically scavenges for carrion, and which can also filter feed when necessary.
The Scotch bonnet is a medium-sized to large species of sea snail, a marine gastropod mollusk in the subfamily Cassinae, the helmet shells and bonnet shells. The common name "Scotch bonnet" alludes to the general outline and color pattern of the shell, which vaguely resemble a tam o' shanter, a traditional Scottish bonnet or cap. The shell is egg-shaped and fairly large, 2 to 4 inches in maximum dimension, with a regular pattern of yellow, orange or brown squarish spots. The surface sculpture of the shell is highly variable: the surface can be smooth and polished, have grooves, be granulated, or even be nodulose on the shoulder of the whorls.
Buccinum undatum, the common whelk or the waved buccinum, is a large, edible marine gastropod in the family Buccinidae, the "true whelks".
Hydractinia symbiolongicarpus is one of the 30 + Hydractinia species known worldwide. This saltwater animal, from here on referred to as Hydractinia, is at the base of the Cnidaria phylum and in many ways, is similar to the freshwater Hydra. In the wild, Hydractinia feed on smaller invertebrates found in the shallow mud, however in laboratory environments they are fed brine shrimp. Hydractinia symbiolongicurpus and its sibling species, Hydractinia echinata, are the two species from the genus Hydractinia on which most work has been published.
Clibanarius erythropus is a species of hermit crab that lives in rockpools and sublittoral waters. It is found in the Mediterranean Sea, Black Sea and eastern Atlantic Ocean from the Azores to Brittany, the Channel Islands and as far north as the south Cornwall coast. Individuals may grow up to a carapace length of 15 millimetres (0.6 in).
Pseudospongosorites is a genus of sea sponges belonging to the family Suberitidae. Currently, the genus is considered as monotypic, consisting of a single species Pseudospongosorites suberitoides. It is found in the Caribbean Sea, the Gulf of Mexico and on the Atlantic coast of the United States as far north as North Carolina. This species is known by the common name Florida hermit crab sponge, so named because hermit crabs often use it as shelter.
Calliactis parasitica is a species of sea anemone associated with hermit crabs. It lives in the eastern Atlantic Ocean and Mediterranean Sea at depths between the intertidal zone and 60 m (200 ft). It is up to 10 cm × 8 cm in size, with up to 700 tentacles, and is very variable in colour. The relationship between C. parasitica and the hermit crab is mutualistic: the sea anemone protects the hermit crab with its stings, and benefits from the food thrown up by the hermit crab's movements.
Alcyonium digitatum or dead man's fingers is a species of soft coral in the family Alcyoniidae. It is found around the coasts of the northern Atlantic Ocean.
Bougainvillia britannica is a marine invertebrate, a species of hydroid in the suborder Anthomedusae.
Hydractinia is a genus of commensal athecate hydroids which belong to the family Hydractiniidae. Hydractinia species mostly live on hermit-crabbed marine gastropod shells.
Adamsia palliata is a species of sea anemone in the family Hormathiidae. It is usually found growing on a gastropod shell inhabited by the hermit crab, Pagurus prideaux. The anemone often completely envelops the shell and because of this it is commonly known as the cloak anemone or the hermit-crab anemone.
The thinstripe hermit crab, Clibanarius vittatus, is a species of hermit crab in the family Diogenidae. It is found in the Caribbean Sea, the Gulf of Mexico and the western Atlantic Ocean.
Paguristes eremita, the eye spot hermit crab, is a species of hermit crab in the family Diogenidae. It is found in the Mediterranean Sea.
Pagurus forbesii is a species of hermit crab in the family Paguridae. It is found in the northeastern Atlantic Ocean and the Mediterranean Sea.
Halecium halecinum, commonly known as the herring-bone hydroid, is a species of hydrozoan in the family Haleciidae. It is native to the eastern Atlantic Ocean, the western Atlantic Ocean and the eastern Pacific Ocean.
Neanthes fucata is a species of marine polychaete worm in the family Nereididae. It lives in association with a hermit crab such as Pagurus bernhardus. It occurs in the northeastern Atlantic Ocean, the North Sea and the Mediterranean Sea.
Labidochirus splendescens, commonly known as the splendid hermit crab, is a species of hermit crab found in the northeastern Pacific Ocean off the coast of North America. It is more heavily calcified and inhabits smaller mollusc shells than most hermit crabs.
Schuchertinia milleri, commonly known as the Miller hydractinia, hedgehog hydroid or snail fur, is a small colonial hydroid in the family Hydractiniidae, found in the eastern Pacific Ocean. It forms mat-like colonies on rocks, or sometimes on the mollusc shells occupied by hermit crabs.
Janaria is a genus of commensal athecate hydroids in the family Hydractiniidae. It is a monotypic genus and the only species is Janaria mirabilis, commonly known as staghorn hydrocoral. It is a colonial species and lives on a shell occupied by a hermit crab. It is native to the tropical and semitropical eastern Pacific Ocean.
Paguristes puncticeps is a hermit crab, in the family Diogenidae. It is found in shallow waters in the tropical western Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico. Like other hermit crabs, it lives inside an empty mollusc shell, which it changes periodically as it grows.
