deep water swimming crab

[jw]

does anyone know what these are? the pollack and whitefish
off the clare coast are comming up stuffed with them
his legs look more like for swimming than walking

[Bradan]

Looks like a velvet swimming crab JW, see here: http://en.wikipedia.org/wiki/Velvet_crab
Get the odd one taking bait fishing from the shore in Connemara and getting hooked, they don't seem to survive as well as the regular shore crabs.

[jw]

bradan, thanks for that, it doesnt seem to have the red eyes and all its legs look
like swimming legs, not just the last two. i rememebr reading some where there
are 57 species of crabs in our waters, not sure where i saw that

[JOHN1]

Looks like a velvet swimming crab JW, see here: http://en.wikipedia.org/wiki/Velvet_crab
Get the odd one taking bait fishing from the shore in Connemara and getting hooked, they don't seem to survive as well as the regular shore crabs.

it's defo NOT a velvet swimming crab.
velvets only have one set of swimming / back paddles

[petekd]

Is this a common thing on the Clare coast JW or is it the first time you have seen it? Dont recall ever finding crab in the gut of any pollack I ever kept before, strange.

[jw]

Named after John Stevens Henslow, the Cambridge professor who gave up his place on the Beagle to Charles Darwin, Polybius henslowii—or the Henslow swimming crab—finds it most comfortable in the warm waters off the coast of Portugal.

Warming ocean currents, however, have allowed the active, swimming, predator to migrate north—and the impact of its presence is beginning to ripple through North Sea ecosystems.

The North Sea is now one degree C warmer than it was 30 years ago, and as it has warmed the number of crab and shrimp larvae in the plankton and adults on the sea bed has increased.

One reason for this increase is the influx of Henslow swimming crabs which, unlike other shrimps and crabs, are able to travel long distances in groups by swimming through the open ocean.

As the number of microscopic decapod—or shrimp and crab—larvae have increased, the number of native bivalves and young flatfish have decreased. It is an excellent example, researchers remarked, of how climate change is propagated through food webs.

Predictions of global climate change suggest that the seas around our coasts will continue to warm. This may mean that we see the appearance of yet more warm water species that could change the ecology of the North Sea further.

The fact that Henslow swimming crabs can occupy part of a coastal ecosystem most crabs cannot means they have the potential to significantly impact the North Sea as an invasive species.

[jw]

http://vimeo.com/2420980

[Bradan]

Interesting JW, especially the bit about replacing other species in the ecosystem. Wonder what other species we will be seeing in greater numbers over the next few years...