The Grapsoidea are a
superfamily of
crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
s; they are well known and contain many
taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
which are terrestrial (land-living), semiterrestrial (taking to the sea only for reproduction), or limnic (living in
fresh water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does inclu ...
). Another well-known member with a more conventional lifestyle is the
Chinese mitten crab
The Chinese mitten crab ('; , "big sluice crab"), also known as the Shanghai hairy crab (, p ''Shànghǎi máoxiè''), is a medium-sized burrowing crab that is named for its furry claws, which resemble mittens. It is native to rive ...
, ''Eriocheir sinensis''.
The delimitation of the
Grapsidae and
Plagusiidae is in need of revision; the latter at least is not
monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
. The same apparently holds true for several
genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomencl ...
in the
Sesarmidae
The Sesarmidae are a family of crabs, previously included in the Grapsidae by many authors. Several species, namely in '' Geosesarma'', '' Metopaulias'', and '' Sesarma'', are true terrestrial crabs. They do not need to return to the sea even f ...
.
The closest living relatives of the Grapsoidea are the
Ocypodoidea. In fact, they seem to be
paraphyletic
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
with respect to each other and it seems warranted to merge the Ocypodoidea into the Grapsoidea.
References
External links
*
Crabs
Arthropod superfamilies
{{crab-stub