In the wild, land hermit crabs eat a wide variety of foods: fallen fruit, decaying wood, leaf litter, plants and grasses, and items washed ashore by the tide. They are not fussy eaters by nature and have even been observed eating fecal matter. Hermit crabs locate food in two ways, by smelling it and by seeing other crabs eating. One way you can test this is to set a dish of one of the smellier 'treat' options listed below into their crabitat. Watch as they come out, wiggle their antennae, and make a beeline for the treat dish. It is fascinating behavior to watch.
What do they need to eat to be healthy?
We are not exactly sure of hermit crabs' exact nutritional requirements, but much progress is being made. For example, we now know that hermit crabs require calcium, carotene and antioxidants just like people do. A crab whose diet is carotene-deficient will fade in color after molting, from a nice reddish or orange color to a washed-out tan or gray. To make sure your crabs get adequate carotene, supplement their diet with brightly-colored vegetables, like corn and carrots. Also you can add ground dried organic marigold petals to your crabs' food. You should be absolutely certain that the marigolds were grown without pesticides before adding them to crab food. For example, the small plastic containers of marigolds that you fine at the local greenhouse are probably treated with pesticides and therefore unsuitable for crab food.
The best diet for a land hermit crab is basically what you feed yourself (with the exclusion of highly-processed foods and sugary snacks, of course). Land hermit crabs are omnivorous and therefore eat just about anything. You can feed them meat, fish, vegetables and fruit (yes even citrus fruit!). Crabs also like tannin-rich foods, such as oak leaves and tree bark. Before giving your crabs these things as food, make sure they are thoroughly cleaned by washing in water (no soap) and allowed to dry -- crabs like their leaves crunchy.
The current wisdom is that commercial crab food is not necessary if you provide your hermit crab with a varied diet of "human grade" food. You can do almost all of your hermit crab food shopping in a regular grocery store. Specialty items you buy from a pet store should be free of unfamiliar ingredients (except for tocopherols, which are natural preservatives). Be sure to examine all labels very carefully and do not purchase any products that contain ethoxyquin or copper sulfate.
In the past couple years, a number of hermit crab food specialty sites have sprung up online. They offer a wide assortment of organic staple food, treats and supplements. Check out the Links page for some great sites featuring a wide variety of hermit crab food.
There has been a lot of interest by hermit crab and their owners in Organic Worm Castings and with good reason. The worm castings are chock-full of nutrients and are also very well-liked by hermit crabs.
A Recipe
Here is a good recipe for regular crab food which satisfies the crabs' taste preference and need for calcium to build a strong exoskeleton.
2 large cuttlebones
1 cup dried rice (any non-instant type)
1 cup unflavored oatmeal
1 tsp. salt, uniodized*
1/4 cup dried plankton, krill or any other very stinky dried sealife
2 tablespoons spirulina powder (you can buy this at almost any health food store)
*Do not use table salt, but sea salt or aquarium salt
Break up the cuttlebones with your hands into nickel-or-dime-size chunks. Using an electric coffee grinder, powder them. Sometimes they get stuck in the blades -- if so, stop grinding and poke them out of the blades and continue grinding. Take all remaining ingredients except the salt and grind them into a sort of lumpy powder fine powder. The krill won't completely grind so just get it to where you can stand it. Add in the salt and any other things you think your crabs will enjoy, such as cornmeal, cracker meal, bread crumbs (unflavored), wheat germ, ground nuts, seeds, etc. Mine especially like a dose of ground flax seed now and then.
