Bloody Hermit Crab- Facts and Photographs

The Bloody Hermit Crab (Dardanus sanguinocarpus) is one of the more colorful smaller hermit crabs in Tanzania. They were first described in 1923 from specimens collected in Hawaii and recent research indicates that it is possible that there is more than one similar looking species. It is possible that the Tanzanian specimens may one day be reclassified. Hermit Crabs spend their lives in empty gastropod shells and the Bloody Hermit Crab is one of the prettier smaller hermit crabs with a splash of red on the upper claws and leg joints.

APPEARANCE

Bloody Hermit Crab’s have a splash of red on the upper claws and near the leg joints. They have two sets of yellow antennae, one short pair in the middle with sensory organs on it and the other longer and extendable outwards. The eyes and eye stalk are also light pinkish brown with blue eyes rimmed in yellow. Normally only the legs and head are seen protruding from the shell .

BLOODY HERMIT CRAB IN THE WILD

Bloody Hermit Crab are very common in Tanzanian waters particularly on the shallower semi protected offshore reefs around 12 to 16 meters in depth. They are easier to spot at night but are seen out during the day.

As with all crustaceans they molt at regular intervals and grow in size and their exo skeletons are very soft making them vulnerable to predators. On each molt they need larger shells which are often in short supply. There can be quite some urgency to find a larger shell after molting and they will actively fight over shells, with larger crabs going as far as pulling a weaker crab out of its shell using its claws.

HABITAT

The Bloody Hermit Crab are found on coral, rubble areas and rocky reefs across the Indo Pacific area from the African coast across to southern Japan, south to Australia and across to Hawaii. They are usually found shallower than 16 meters and we have not seen any deeper than this.

DIET

Halloween Hermit Crab are omnivores and eat detritus, algae and meat and scavenge as well.

REPRODUCTION

The Males chemically detect when a female is fertile and approach them, often holding onto the female until she is ready to mate with them. Once the eggs are fertilised they are kept on the underside of the female inside their shell. When the eggs hatch the larvae are planktonic until they are large enough to find small shells.

BLOODY HERMIT CRAB CLASSIFICATION

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Infraorder: Anomura
Family: Diogenidae
Genus: Dardanus
Species: D. sanguinocarpus