Post by Sach-Crabministrator on Jun 14, 2010 14:58:28 GMT -5
Hermit Crab Development
-Mating
Land hermit crabs develop to sexual maturity around age 2 years and then migrate toward the shore when it's time to make baby crabs. This happens at various times of the year at specific points in the lunar cycle, but varies from species to species. In species where resources are more limited, some species have been noted to reach maturity younger & have faster reproduction cycles in a seeming effort to increase the population. In our commonly kept clypeatus, this happens in the late summer-early fall in the Carribean. Both the male & female come partway out of their shells so that he may transfer a mass of spermatophores to her through her gonopores. This fertilizes her eggs & they each go on their merry way.
-Development
The females then attach the fertilized eggs to their pleopods (these are the small appendages back inside the shell). The eggs will incubate for about 30 days. During this time, Mama crab will stay out of water as it will cause her eggs to hatch permaturely. She keeps just enough water in her shell to keep her gills moist during this time. The number of eggs depend on Mama's size, varying from 400-1000 for smaller crabs to as many as 50,000 for bigger crabs. This egg mass starts out as a red to orange color & as they develop, turn gray & then clear as the tiny babies grow. When they are ready to hatch, Mama crab journeys back to the shore. She will then either pass the eggs up to her claws to fling them out into the sea, place them on shore-line rocks to be washed away (a practice seemingly exclusive to clypeatus) or she will go into the water & pump in & out of her shell to flush the eggs out. They hatch immediately upon contact with the salt water. This ends Mama crab's time with her young; which are now called zoae.
The zoae will float around the sea with the plankton for about 3-4 weeks while they go through about 5 stages (depending on species) of development. At the end of this stage, they are called megalopae. At first, they look a lot like lobsters but look like "normal" hermit crabs within days. It is at this stage they begin to come out of the water onto land. Over the first few days, they will go in & out of the water in search of an abandoned mollusk shell to protect their delicate abdomens as the little megalopae begin their terrestrial lives. They will bury down in the sand for their first molt. Within this period of time their gills modify to the point where they can no longer be submerged in water for extended periods without drowning. This entire process happens in under 3 months; amazing!
Crabs molt as they grow bigger; a process that happens as often as every few weeks for smaller crabs or as little as every 18 months for really big crabs. {go HERE to learn more about molting} Over their lifetime (which can be decades), the crabs will molt & grow & breed every year.
*Note that it is impossible for the average crabber to breed land hermit crabs in captivity.