Hermit crab

From ReefPedia

Hermit Crabs are one of the most common types of inverts available to make up a clean up crew in a tank but are they really all that good? As juveniles they are generally omnivores that scavenge food off the bottom of the tank and pluck at new algae growth from live rocks. They readily eat any sort of meaty foods that fall to the substrate. However as they grow they start to get bolder and begin hunting as well as scavenging. All too often they turn their attention to the prized snails looking for new homes for themselves and finding an extra snack in the process. As they get larger still they start to prey on other bottom dwelling animals. As they become larger they require larger shells to inhabit and they become stronger thereby able to knock done some poorly fastened corals or small rocks.

Despite their potential for aggression they remain in high demand and favour for a lot of aquarists as part of the cleanup crew. They are easy to care for overall, hardy and they do a good job keeping the detritus to a minimum. Their requirements are fairly simple, they require stable water conditions and plenty of spare shells to move into when they out grow their current home. There should be at least two empty shells in the tan for every hermit crab to reduce aggression amongst other hermit crabs and to reduce the chances of them killing the snails to try on a new shell. Most LFSs should sell a wide variety of shells for you to use, personally I prefer purchasing shells for my hermits at a local craft store and boiling them to ensure they are disinfected.

As hermit crabs grow, they molt their exoskeleton. During this molting period their bodies are very soft and they are more vulnerable to predation and will go into hiding. If you see the molt, it's recommended, but not necessary to remove the skeleton.

Blue Leg Hermit Crabs (Clibanarius sp.) These are one of the most widely available hermit crabs. They remain relatively small growing only about one inch. They are generally herbivores and will eat all types of algae in the tank, with a preference to new growth. They can easily starve to death in a tank with little to no algae unless fed a supplemented diet of dried nori.

Left Handed Hermit Crabs (Calcinus sp) These hermit crabs, referred to as red legged hermit crabs, have uneven sized claws, with the left one generally being larger then the right claw. They are reef safe with the exception that they can prey upon snails if there isn't enough shells present. They are omnivores wit ha preference to new algae growth. In the wild they are generally found in tide pools and shallow reef areas.

Red Scarlet Hermit Crabs (Paquristes sp.) (Pictured Right) This is another common and generally peaceful hermit crab that is commonly available for sale. They remain relatively small and will rarely attack other tankmates including snails unless they are in need of shells. They are great for eating filamentous algae and cyanobacteria. They will also pick at detritus that has fallen to the bottom of the tank. In the wild they are found in offshore reefs.

Common Hermit Crab (Dardanus sp.) (Pictured Left): The Common Hermit Crab has hairy red legs and unequal-sized claws (the left one is generally larger) that is used to to catch food. It is commonly introduced to the tank as a hitchhiker from the live rock and will gladly feed on tube worms, molluscs, and fish once it's large enough to catch them. However they are also good for sifting through sand in search of small food particles, worms and pods. Only one of these hermit crabs should be kept in a tank as it will kill any other crab it can find. They are generally nocturnal creatures.

   Original article contributed by Fish Tanks and Ponds