Underwater photo of a hermit crab and gastropod shell
Hermit crabs fighting over a shell
As hermit crabs grow they require larger shells. Since suitable intact gastropod shells are sometimes a limited resource, there is often vigorous competition among hermit crabs for shells. The availability of empty shells at any given place depends on the relative abundance of gastropods and hermit crabs, matched for size. An equally important issue is the population of organisms that prey upon gastropods and leave the shells intact.[7] Hermit crabs that are kept together may fight or kill a competitor to gain access to the shell they favor. However, if the crabs vary significantly in size, the occurrence of fights over …show more content…
Before that time, at least some hermit crabs used ammonites' shells instead, as shown by a specimen of Palaeopagurus vandenengeli from the Speeton Clay, Yorkshire, UK from the Lower Cretaceous.[14]
[edit] As pets
Photo of four hermit crabs.
Four hermit crabs in an aquarium
Several marine species of hermit crabs are common in the marine aquarium trade. Of the approximately 15 terrestrial species in the world, the following are commonly kept as pets: Caribbean hermit crab (Coenobita clypeatus), Australian land hermit crab (Coenobita variabilis), and the Ecuadorian hermit crab (Coenobita compressus). Other species such as Coenobita brevimanus, Coenobita rugosus, Coenobita perlatus or Coenobita cavipes are less common but growing in availability and popularity as pets.
These omnivorous or herbivorous species can be useful in the household aquarium as scavengers, because they eat algae and