Some species of starfish have the ability to regenerate lost arms and can regrow an entire new limb given time.[48] A few can regrow a complete new disc from a single arm, while others need at least part of the central disc to be attached to the detached part.[24] Regrowth can take several months or years,[48] and starfish are vulnerable to infections during the early stages after the loss of an arm. A separated limb lives off stored nutrients until it regrows a disc and mouth and is able to feed again.[48] Other than fragmentation carried out for the purpose of reproduction, the division of the body may happen inadvertently due to part being detached by a predator, or part may be actively shed by the starfish in an escape response.[24] The loss of parts of the body is achieved by the rapid softening of a special type of connective tissue in response to nervous signals. This type of tissue is called catch connective tissue and is found in most echinoderms.[53] An autotomy-promoting factor has been identified which, when injected into another starfish, causes rapid shedding of arms.[54]