Pilumnus vespertilio

Pilumnus vespertilio (commonly known as Hairy Crabs)

Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Decapoda
Infraorder:	Brachyura
Section:	Eubrachyura
Subsection:	Heterotremata
Superfamily: Genus:	Pilumnoidae Samouelle, 1819 Pilumnus

Where seen?

Hairy crabs are commonly seen on rocky and coral rubble areas on many of our shores. The "teddy-bear" of crabs, these hairy little creatures fluff up in the water and look positively cuddlesome. But they are hard to spot and usually well hidden, especially during the day. They are more active at night, but even then, they usually scuttle into the nearest crack or crevice at the first sign of danger.
These little crabs are not the same as the large 'Hairy crabs' that are served in our restaurants as seafood.

Features:

Body width 3-5cm. As its name suggests, the hairy crab is indeed quite hairy. Its body and limbs are covered with long, silky hairs. These trap sediments allowing the crab to blend perfectly with its surroundings. In the water, its hairs 'fluff up' breaking up its body outline. It also moves slowly and thus overlooked as some bit of drifting rubbish. It has large claws, some with thick black fingers.

What do they eat?

The Common hairy crab eats mainly seaweed. It may also eat toxic zoanthids (colonial anemones) and this makes the crab mildly poisonous. Various hairy crabs on our shores have been observed nibbling on hard seaweeds, sponges and even appearing to snack on bristleworms and possibly having a taste of a nudibranch.

Status and threats:

Several of our hairy crabs are listed among the threatened animals of Singapore. 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.

Credit: http://www.wildsingapore.com/wildfacts/crustacea/crab/pilumnidae/pilumnidae.htm