learn only 3 things about them ...
They use a leaf, flat shell or other rubbish to hide under.
Specialised legs grip the disguise.
night they swim above the leaf to hide from predators
seen? This shy and sneaky crab is commonly seen, by the
sharp-eyed observer, especially on our Northern shores. To spot one,
look for odd movement in a leaf or a shell, perhaps moving too quickly
or against the currents. Often in mangroves, near seagrasses but also
on shores near reefs, even under jetties in calm waters.
Features: Body width to about 1.5cm. Named for its habit
of carrying a leaf as a mobile hiding place, it may also "carry"
a clam shell, a flat piece of wood or other bits of flotsam. Two pairs
of legs are short and bent permanently over the back. These legs are
tipped with hairy pads to cling onto the leaf or shell. Two other
pairs of legs are longer and fringed with hairs. These fringed legs
are used like paddles to swim slowly about.
The body is flat and somewhat rectangular. It has rather long antennae
for a crab. Pincers small and held flat against the body. Some may
have one enlarged and inflated pincer, while others have pincers of
The crab is more active at night. At this time, there are few predators
above the water that can spot them in the dark. So at night, it swims
with the leaf under it, to hide from aquatic predators below. If it
senses danger from above, however, it will quickly flip under the
leaf! During the day, it often hides under the leaf, half buried in
the sand or mud.
What does it eat? The crab is
a scavenger, eating any dead plants or animals that it comes across.
Status and threats: Leaf porter
crabs are not listed among the threatened animals of Singapore.
However, like other creatures of the intertidal zone, they are affected
by human activities such as reclamation and pollution. Trampling by
careless visitors also have an impact on local populations.
Changi, Apr 04
Two kinds of legs.
This one was 'carrying' a clam shell.
Changi, Jul 02
Seldom seen upper side.
Labrador, Jan 06
Some have one enlarged pincer.
Raffles Marina, May 05
porter crabs on Singapore shores
Dorippidae recorded for Singapore
Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity
- Ng, Peter
K. L. and Daniele Guinot and Peter J. F. Davie, 2008. Systema
Brachyurorum: Part 1. An annotated checklist of extant Brachyuran
crabs of the world. The Raffles Bulletin of Zoology. Supplement
No. 17, 31 Jan 2008. 286 pp. (Online
PDF on the Raffles Bulletin of Zoology website)
- Lim, S.,
P. Ng, L. Tan, & W. Y. Chin, 1994. Rhythm of the Sea: The Life
and Times of Labrador Beach. Division of Biology, School of
Science, Nanyang Technological University & Department of Zoology,
the National University of Singapore. 160 pp.
- Wee Y.C.
and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore.
National Council on the Environment. 163pp.
- Ng, P. K.
L. & Y. C. Wee, 1994. The
Singapore Red Data Book: Threatened Plants and Animals of Singapore.
The Nature Society (Singapore), Singapore. 343 pp.