Hermit crab babies hatch from eggs. Mama Crab carries them around until they change color from a rusty brown to light blue, at which point they've finished developing. That's when the mother crab takes her eggs to the water and drops them in to hatch. Many animals have more than one offspring at a time, but hermit crabs, have many in one effort.
Female hermit crabs lay between 800 and 50,000 eggs at a time. The actual number that an individual hermit crab lays depends on her size. As you might expect, larger female hermit crabs lay more eggs than the smaller ones do.
Why So Many?
Hermit crabs are programmed to lay so many eggs at once because in the wild things like predators and less-than-optimal conditions keep a lot of the eggs from hatching, or make short work of the babies who do hatch. By producing hundreds and thousands of eggs, they're playing the odds that a good number will survive to hermit crab adulthood.
Perfect Conditions Required
When you consider all of the conditions required for hermit crabs to reproduce, and how many of them can go wrong, you'll be amazed that hermit crabs exists at all. Hermit crab eggs require seawater to hatch, so even a land hermit crab has to get to the shore to give her kids a good shot at survival. The temperature of the water needs to be between 72 and 80 degrees Fahrenheit, so unseasonably cold or hot weather can be another issue that works against a healthy batch of babies. Once hatched, the tiny crabs feed on things like brine shrimp as they continue to develop.
Hermit Crab Hatchlings
Hermit crab hatchlings are born in the water and remain there for a time. When they're first hatched, baby hermits look a lot like itty bitty shrimp. They molt up to six times to reach full crab form. When baby hermit crabs finally come ashore, they look like miniature hermit crabs and are ready for a shell.
Hermit crabs do their best reproducing in the wild. They rarely produce any offspring in captivity. In order to successfully breed hermit crabs in captivity, it's vital that you recreate all of the conditions that would be present in nature, all the way from setting your crabs up on a blind date to setting the mood for mating, as well as providing a simulated beach and sea where Mother Crab can deposit her eggs. Captive breeding may be successful in an outdoor pond, and an indoor saltwater tank is a possibility, too.
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Elle Di Jensen has been a writer and editor since 1990. She began working in the fitness industry in 1987, and her experience includes editing and publishing a workout manual. She has an extended family of pets, including special needs animals. Jensen attended Idaho and Boise State Universities. Her work has appeared in various print and online publications.