Dardanus megistos

Dardanus megistos, the white-spotted hermit crab or spotted hermit crab, is a species of hermit crab belonging to the family Diogenidae.

Etymology
The genus name Dardanus refers to the son of Zeus and Electra in Greek mythology, while the species name megistos is the superlative of the Greek word mega, therefore it means the largest.

Distribution
This species is present in the Indo-Pacific region from East Africa to the South China Sea, Australia and east to Hawaii.



Habitat
These tropical reef-associated crabs occur in coral reef, lagoons, rocky platforms, sand and seagrass beds, from littoral and subtidal zones to deep waters, at depths up to 50 m.

Description
Dardanus megistos can reach a body length of about 20 cm. These large crabs have a bright red body with small white eyespots surrounded by black. Their bodies are covered with long erect coarse hairs of a dark red color. They have a pair of long white primary antennae or antennules, a pair of secondary antennae, stalked green brown eyes and three pairs of mouth appendages. The stalks of the eyes are reddish with a basal white spot. The soft, asymmetrical abdomen is spiral-shaped, useful in keeping in the shell, with a five-piece tail (telson and uropods). Like all decapod crustaceans, they have ten legs. The first pair of legs carries the  pincers ( chelipeds). The left plier is bigger than the right one.

Biology
The white-spotted hermit crabs are gonochorics, the eggs are carried on the female's abdomen. They also are opportunistic omnivore, mainly feeding on small invertebrates (worms, molluscs, etc.) and they are also reported to feed on holothurians. Commonly these crabs perform a precopulatory courtship ritual. Usually the sperm transfer is indirect. They may live up to 30 years. These crustaceans usually inhabit a large shell of a gastropod, consequently only the cephalothorax and the first three pairs of legs are visible.