Brachyuran Crab Database

   Long-legged Spider Crab
Common Name(s):
 Long-legged Spider Crab

Scientific Name:
 Macropodia rostrata
Usual Size: 
> 29 mm (male)
> 16 mm (female)

Photograph  by Steve Trewhella


As its name suggests this crab has very long legs. It has a very triangular shell and it looks like a Daddy Long-legs. 

Click on the text for a brief video

Macropodia  swimming

If it is caught in a net or stranded at low tide, it resembles a crumpled up twig. However, when under water it swims with a curious bicycle-like motion. It often places weed all over its legs and shell which gives it its other name of Decorator Crab. There are several species of crabs in the genus Macropodia and differentiating them is very tricky.

Photograph by Andy Horton

Photograph by Brian May (Eastbourne)

Although not clear from the photographs, all the spider crabs have ten legs including the major claws. 

Similar species:

Macropodia tenuirostris
Macropodia deflexa
Both these species are so close that it is near impossible to separate them in the sea and rockpools and difficult in captivity and difficult with dead specimens under a magnifying glass. 





Additional Notes:

In Spain,where I worked on it, Dictyota linearis is the alga of choice for decoration.
Dr. Edwin Cruz-Rivera 
University of Guam Marine Laboratory 

All the specimens I have collected (hundreds) have not been decorated with weed, and associated with hydroids. My collection are is on the shore off the Sussex coast, English Channel, e.g. Kingston Beach, Shoreham-by-Sea, where it is common just below Chart Datum in autumn. 

Andy Horton, BMLSS.

28 & 30 Ocotber 2014
Long-legged Spider Crabs were discovered on Maenporth Beach, Falmouth, Cornwall, mostly decorated with red seaweed but some of them in the rockpools had green seaweed atatched to their legs and carapace. 

Report by Edward Walls (16)

14 July 2003
Kingston Beach
Although they are six metre plus high tides, the water does not recede every far only down to 0.8 metres above Chart Datum, so the rockpooling was only to collect a few prawns for the wrasse in my home aquaria

The appearance of four large Long-legged Spider Crabs (1) was unexpected, although they have been caught in July before.The largest specimen measured 18 mm from the rear of the carapace to the eyes but the spread of legs and claws was 100 mm.

Close-up pictures

Crabs of the Seashore (Link)

Information wanted: Please send any records of this crab, with location, date, who discovered it, how it was identified, prevalence, common name and any other details to 
Shorewatch Project EMail
All messages will receive a reply. 
Shorewatch Project


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