Page "Hermit crab" Paragraph 8

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.

Hermit crabs that are kept together may fight or kill a competitor to gain access to the shell they favour.

However, if the crabs vary significantly in size, the occurrence of fights over empty shells will decrease or remain non-existent.