Hermit(kabuklu yengeç)

Several marine species of hermit crabs are common in the marine aquarium trade. These omnivorous or herbivorous species are useful in the household aquarium as scavengers, because they eat algae and debris.

Hermit crabs in an aquarium.

The scarlet hermit crab, or red reef hermit crab, Paguristes cadenati, is a handsome and interesting species with a bright red body and yellow eyestalks, and stays rather small (about 2–5 cm / 1–2 inches across). Smaller species of a similar passive nature include the zebra hermit crab (brown legs with white bands), the red-tip crab and blue-legged crab.In Europe, the common hermit crab, Pagurus bernhardus, is popular. While most species available in pet stores are small like those listed above, and are simply scavengers, others may grow quite large (some on the Pacific coast can grow to 30 cm / 12 inches) and may eat coral, clams and other crustaceans. Most marine hermit crabs do well in a salinity of between 1.023 and 1.025 (measured in specific gravity), and temperatures between 4–14°C (temperate species) and 24–27°C (for tropical species), with algae to graze on, and a variety of shells to change into. They will happily switch shells frequently if given the opportunity - an interesting display to watch.

There are approximately 15 terrestrial species in the world, and of those, the following are commonly kept as pets: Caribbean hermit crab, Coenobita clypeatus, and the Ecuadorian hermit crab, Coenobita compressus. Other species such as Coenobita brevamanus, Coenobita rugosus, Coenobita perlatus or Coenobita cavipes are less common but growing in availability and popularity as pets. In certain regions of the Caribbean, such as Jamaica and the Florida Keys, hermit crabs are commonly used in a sport known as crab racing, where they are placed in the center of a ring and whichever crab reaches the outside of the ring first wins.

Hermit Crabs used to be thought of as a "throwaway pet" that would only live a few months, but with proper care, including mimicking the environment they originated from, and proper feeding, they can thrive for many years. For example, Coenobita clypeatus is commonly listed as having a 20 year lifespan^[5]and some have lived longer than 32 years^[6]. Golf ball sized crabs are most probably younger than ten years old, mandarin sized crabs are likely to be at least in their twenties, and jumbo sized crabs are between twenty and thirty years old^[7].

In general, hermit crabs are social animals and should be kept in groups^[8]. They need higher moisture and heat than an air conditioned home, and they must have an adequate depth of substrate to allow them to dig while moulting. and must be kept accordingly.

There is some controversy surrounding the use of painted shells. The detractors claim that the paint is toxic and uncomfortable^[9], that the use of painted shells encourages buyers to select a crab based on its shell (which will be vacated eventually) and not on the health or personality of the crab, that crabs often get stuck in the shells^[10], and that the methods for moving the crabs into painted shells are inhumane. Some anecdotal evidence suggests that crabs will prefer natural shells if given the choice (and if size and shape is not a factor).

A hermit crab will sometimes inexplicably die in the first few weeks after purchase, sometimes called Post Purchase Syndrome. This is thought to be linked to the stress of changing surroundings^[11]. Usually the process of being shipped, moved into the pet store, and then brought home is fairly quick, causing a great deal of change in a short period of time. Thus it is important to touch a new crab as little as possible for the first few weeks, possibly even isolating it from other crabs.

A crab preparing to moult will sometimes go limp and apparently lifeless^[12]. Thus it is important to distinguish between live and dead crabs by the strong fishy odor given off by dead crabs^[13]. However, this is not always a reliable measure of death; not all dead crabs will have a noticeable smell.