Red Face Hermit crab
Scientific name: Dardanus megistos
Hermit crabs in general are found world wide. There are about eight hundred known species of hermit crabs in the world, most of which are aquatic and live in estuaries, intertidal areas and reefs and on the sea floor at various depths. This particular species is found mainly in interdial rocky shore ecosystems of the east coast of Australia.
Hermit crabs are actually not closely related to true crabs. They are decopods which have 5 pairs of legs. Most species of hermit crabs have long soft abdomens which are protected from predators by the adaptation of carrying around a salvaged empty seashell, into which the whole crab's body can retract. Most frequently hermit crabs utilize the shells of sea snails, marine gastropod molluscs. The tip of the hermit crab's abdomen is adapted to clasp strongly onto the columella of the snail shell. As the hermit crab grows in size, it has to find a larger shell and abandon the previous one. Hermit crabs eat both animals and plants. For example mussels, small plankton and worms. They also are called scavengers because they will eat dead plants and animals.
Mostly crabs are scavengers. Its enemies are sea birds, fish, octopuses, crabs, and other hermit crabs.The reproductive organ of hermit crabs are located near and just below the crab’s heart and open to the outside at the base of the last pair of walking legs in the male. In the female, they are located at the base of the middle pair of walking legs.
Female hermit crabs usually lay their eggs shortly after copulating, however they can also store sperm for many months. The eggs are fertilized as they are laid by passing through the chamber holding the sperm. The eggs are carried and hatched in a mass attached to the abdomen inside the shell. The number of eggs is usually large, but depends on the crab’s size.
The developing crabs go through four stages, two of which (the baupilus and protozoea) occur while still in the egg. Hermit crabs release their eggs in the ocean, near the shore. Because of this, hermit crabs cannot reproduce in captivity without special equipment to simulate a shoreline. Most crabs hatch at the third stage, the zoea. This is a larvae stage wherein the crab has several long spines, a long narrow abdomen, and large fringed antennae. The fourth stage of development is the magelops.
Hermit crabs can live to 6 to 15 years, but many live only to 6 to 12 months.
As the only protection from predators for hermit crabs is the shell and there is always stiff competition anyway for the correct size shells the impact of ocean acidification may well see many of theses species being unable to grow to reproductive age because there will not be enough variety in shell homes. In most ecosystems they are common and it is generally known hermit crabs because of the specific nature of their egg laying capacity are difficult to keep in activity and are not generally over collected.