The hermit crab


Pagurus_bernhardus
 
HERMIT CRABS are decapod crustaceans of the superfamily ———–PAGUROIDEA.  Most of the 1100 species possess an asymmetrical abdomen which is concealed in an empty GASTROPOD SHELL, carried around by the hermit crab, into which its whole body can retract..  Most frequently, hermit crabs use the shells of sea snails.
 
The tip of the hermit crab’s abdomen is adapted to clasp strongly on to the COLUMELLA of the snail shell.  As the crab grows, in size, it must find a larger shell and abandon the previous one.  This habit of living in a SECOND-HAND SHELL, gives rise to the popular name HERMIT CRAB, by analogy to a hermit who lives alone.  Many hermit crabs use VACANCY CHAINS (very interesting) to find new shells.  When a new, bigger shell becomes available, hermit crabs gather round it and form a kind of QUEUE —— from largest to smallest.  When the largest crab moves into the new shell, the 2nd largest crab moves into the newly-vacated shell, thereby making its previous shell available to the 3rd largest crab and so on.
 
Hermitcrab_bw
 
Hermit crabs often GANG UP on a hermit crab with what they perceive to be a better shell, where they will, actually, pry its home away from it, and then compete for it, and one will, ultimately, take it over.  Most species are AQUATIC, and live in varying depths of salt water.  Tropical areas host some TERRESTRIAL SPECIES, though, even those, have aquatic larvae and need access to water for reproduction.  Most hermit crabs are nocturnal.  A few species do not use  a MOBILE HOME, and inhabit immobile structures, left by POLYCHAETE worms, VERMITED gastropods, CORALS & SPONGES.
 
Hermit crabs are, often, seen as THROWAWAY PETS, that would live only a few months, but species such as COENOBITA clypeatus have a 23year life span, if properly treated, and some have lived longer than 32yrs.  In general, and despite their MONIKER, hermit crabs are social animals, that do best in groups.  In the wild they can be found in colonies of a 100 or more, and therefore many sellers encourage the purchase of more than one crab.
 
hermit-crabThe hermit crab terranium environment requires a controlled environment, with a temperature around 75-85degrees F, and a humidity around 70-80degrees.  They need salt and fresh water.  They are SCAVENGERS, and so can be given fruits and vegetables, as long as they are not put in preservatives.  Substrate needed is sand mixed with coconut mulch or crushed coral substrate, that is deep enough to allow them to completely bury themselves while MOULTING.  During moulting, they should not be dug up.  Those that are dug up regularly, will create a moult-inhibiting hormone called XANTHURENIC ACID.  The exoskeleton that is left behind, is eaten by the newly-moulted crab.  The exoskeleton contains much-needed nutrients, including Calcium.
 
 POST NOTE
 
 The HERMIT CRAB gets its name, because it abandons its old shell and goes in search of bigger shells, just like a hermit without a home of its own.  Inspired by this peaceful exchange of shells, Japanese media design artist, Aki Inomata, has designed a project titled, Why not hand over a ‘SHELTER’ to Hermit Crabs ?  It explores the theme, by designing new ‘SHELTERS’, in the shape of ‘world cities’.  Theses new homes, for the crabs, represent the abstract perception of changing nationalities and identities.
 
According to HUFFINGTON POST, Inomata explores the idea of changing nationalities through migration, displacement, and the very primal search for a physical and symbolic home.  Clearly, the hermit crabs became the perfect metaphor for migrants and refugees.  Inomata says, “Though the body of the hermit crab is the same, according to the shell it is wearing, its appearance changes completely.”  The SHELTERS, designed in the shape of various cities worldwide, represents the changing identities of migrants.
 
 
 
 
 
 

 

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