Blue-leg Hermit Crab, Clibanarius tricolor

Blue-leg Hermit Crab, Clibanarius tricolor. Crab taking up residence in an unknown abandoned shell. Underwater photograph taken in coastal waters off Cozumel Island, Quintana Roo, March 2021. Photograph courtesy of Marina Sutormina, Stockholm.

General Information: The Blue-leg Hermit Crab, Clibanarius tricolor, is a member of the Diogenidae Family of Hermit Crabs, the left-handed hermit crabs, that are sometimes referred to as “left handed hermit crabs” due to the left claw being larger than the right which is atypical of hermit crab species. They are also known as the Blue-legged Hermit Crab, the Blue-leg Reef Hermit Crab, the Dwarf Blue Hermit Crab, the Equal-handed Hermit Crab, and the Tricolor Hermit Crab and in Mexico they are known as Caranguejo Anão Patas Azuis.

Identification: The Blue-leg Hermit Crab are easy to recognize due to blue legs with red banding. Their ambulatory legs are strikingly colored being blue, orange, and yellow banded. They have bright orange antennae. They are a small to medium-sized crab being a maximum of 2.5 cm (1.0 inches) in length and can be found in shells that are up to 3.8 cm (1.5 inches) in diameter. They utilize snail shells as their portable shelters for protection of their soft and fragile bodies. They have equal sized claws and unique to the family, being ambidextrous, capable of utilizing either claw equally. The males are larger than the females but the sexes cannot be easily separated and as there is no visible external sexual dimorphism.

Habitat and Range: Blue-leg Hermit Crabs are found in groups in the low intertidal and shallow sub-tidal zones within clear water, adjacent to rock and coral structures over sand substrate at depths up to 7 m (20 feet). They are known to exhibit aggressive behavior and will attack snails and other hermits in their shells, trying to convince their prey to give up their shell which they then take over. They are always in search of new larger shells, favoring  Cerith Shells. They can be found in large aggregations during low tides in the intertidal zone. They have a high site fidelity with daily home ranges that are less than 2 m (7 feet). The Blue-leg Hermit Crab is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean. They are one of the most abundant and widespread small hermit crabs of the Caribbean and the Western Atlantic.

Diet:  The Blue-leg Hermit Crabs are herbivores primarily feeding on green hair algae, cyanobacterium, seaweed and detritus.

Reproduction and Life Span:  Reproduction for the Blue-leg Hermit Crab occurs a short time following a female molt and involves broadcast spawning, with the females releasing up to 600 eggs and males simultaneously releasing sperm into the water column. Their larvae are “shrimp-like” and quickly molt out of their exoskeletons and seek out a gastropod shell. They continually seek out bigger and better shells. The Blue-leg Hermit Crab has not been bred in captivity. In the wild their life spans have not been determined; in captivity they only survive for up to two years.

Conservation Status:  From a conservation perspective the Blue-leg Hermit Crab has not been formally evaluated. Due to their abundance and wide distribution range they should be considered to be of Least Concern. They are valued and utilized by the aquarium trade due to their small size, colorful appearance, low maintenance, hardiness requiring little care, and their janitorial capabilities, ridding an aquarium of numerous unwanted materials. They are also considered to be an essential component of the ocean’s ecosystem, ridding the environment of a wide variety of undesirable debris.

Synonyms:  Clibanarius brachyops, Clibanarius hebes, and Pagurus tricolor.