NEWS 115
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Trichodactylus kensleyi
Freshwater crabs from Paraguay
Crabs are very entertaining aquarium-
dwellers. They appear intelligent to the
observer and display a wide variety of
behavioral patterns.However,you should be
aware that crabs are also rather destructive
and may regard all their tankmates - plants
as well as livestock - as potential sources of
food, and can be very quarrelsome among
themselves.
Aquarium Glaser has recently imported
some splendid large (carapace width 5-8
cm; these creatures are larger than hand-
size if you include the legs!) freshwater crabs
from Paraguay. They are thought to be
Trichodactylus kensleyi.
The hair responsible
for the genus name (Trichodactylus = hair
finger) on the terminal joint of the
pereopods can readily be seen in the
photos.
Male and female crabs can always be told
apart very easily by the form of the tail
folded beneath the body, the pleon. But
even without turning the crabs on their
backs the males can be readily recognized
by their comparatively larger claws.
In the case of marine crabs the young
usually undergo several free-swimming
larval stages before they adopt a bottom-
oriented way of life. By contrast, in the
freshwater
crabs
of
the
family
Trichodactylidae, to which
Trichodactylus
Trichodactylus kensleyi
, male
kensleyi
belongs, the entire life cycle takes
place in fresh water.
The Trichodactylidae are a family of
freshwater crabs found exclusively in South
America. There are 51 species divided
among 15 genera. Although these crabs are
generally commonplace where they occur
and used as food by the local people, as far
as we know there have not been any
previous commercial importations of any of
the species.
There is also practically no literature on the
behavior of these animals,just a fairly recent
study investigating the behavior of the
species
Trichodactylus panoplus.
This
indicates that these crabs prefer gravel
bottoms, are both diurnal and nocturnal
(but exhibit more activity at night), and are
usually relatively peaceful among them-
selves. In the wild these omnivores usually
occur in a balanced 1:1 sex ratio. Un-
fortunately the populations of numerous
species are declining noticeably as a result
of human alterations to the environment.
Hence it would be nice if aquarists were to
devote themselves to the maintenance and
breeding of these crabs and thus provide
the basic data required for conservation
projects.
Males have larger claws.
These crabs are comparatively peaceful
among themselves.
Trichodactylus kensleyi
, female
Literatur
:
Zimmermann, B. L., Aued, A.W., Machado, S.,
Manfio, D., Scarton, L. P. & S. Santos (2009):
Behavioral repertory of Trichodactylus
panoplus (Crustacea:Trichodactylidae) under
laboratory conditions. Zoologia (Curitiba,
Impr.) [online].Vol.26, n.1, pp. 5-11
