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Diving with British Marine Life: the European Spider Crab

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If you’ve dived in the UK chances are you’ve encountered a European spider crab (Maja brachydactyla). While often overlooked, these crabs display a wide range of behaviours making them brilliant photography subjects and great characters to observe on a dive.

M. brachydactyla is found on the South and West Coast of England and Ireland and is the largest spider crab in the UK. European spider crabs are characterised by their red-yellow body colouration and triangular carapace bearing two distinct frontal spines between the eyes. The claws are relatively narrow with white tips, while their walking legs have dark tips.

Their carapace is covered in tiny barbs, which they use to fix an array of algae in order to ‘decorate’ a fresh moult. Such behaviour is well documented in majid crabs and helps to camouflage their bright exoskeletons. Paul Naylor, marine biologist, photographer and author of Great British Marine Animals, showcases this decorative behaviour on his Vimeo profile.

As well as actively masking their exoskeleton, spider crabs play host to a wide range of epibionts. Sessile organisms such as barnacles, anemones and tunicates settle onto their carapace in their larval stage. This relationship is known as mutualistic; the host benefits from protection from predators via camouflage, and the epibionts (an organism that lives on the surface of another organism) are exposed to sediment resuspended by the host, protection from slow moving predators, and better dispersion of offspring.

Documentary worthy aggregations of spider crabs also occur close to shore around the UK; but surprisingly these dense aggregations, also known as mounds, are driven by moulting rather than breeding. I am yet to witness this phenomenon, but look forward to the day I do!


Hear more from Georgie here: https://georgiebullphotography.home.blog/

Georgie is a Marine Biology and Coastal Ecology student at Plymouth University and an active diver in the South West of England. This year she will be completing the HSE Scuba qualification with the University in the hope that scuba will become part of her future career. She is particularly interested in native species and has a soft spot for elasmobranchs and molluscs.

Marine Life & Conservation

Our Seas urge Scotland to bring back Inshore Limit

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Our Seas call on Scotland’s First Minister, Nicola Sturgeon, and the Scottish Government to follow their own policies and stop the chronic destruction of our seabed by urgently reinstating a coastal limit on bottom-trawl and dredge fishing. Sign the petition here.

Scottish coastal seas have been driven into decline due to decades of mismanagement. Destructive bottom towed fishing gear has had free access to over 95% of our inshore waters since the 1980’s, to the detriment of habitats, biodiversity, fisheries, and communities.

In 1889 a law was passed to protect fish stocks and small boats by banning trawling (except by sail) from within three nautical miles of the shore. Catastrophically the law was removed in 1984 against a backdrop of the industrialization of fishing technology, breaches of the Three Mile Limit, and declining offshore fish stocks.  Access to the inshore appeared to improve catches for a short while, but inevitably led to the rapid decline of fish stocks as seabed habitats – vital nurseries and shelter for many species – were destroyed.

See the trailer of their film The Limit below:

Our Seas are asking you to sign their petition to Bring Back the Fish and Bring Back Scotland’s Inshore Limit. You can sign the petition by clicking here.

For more information about the work of Our Seas visit their website by clicking here.

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And the winner of our AP Diving 45M Ratcheted Pocket Reel competition is…

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We’d like to say a big thank you to all of you who entered our competition to win an AP Diving 45M Ratcheted Pocket Reel from our good friends at AP Diving!

As usual, lots of you entered… but there can, of course, be only one winner!

And that winner is…

  • Simon Nicholls from the UK.

Congratulations Simon – your prize will be on its way to you soon!

Not a winner this time? Don’t worry – there are plenty of other competitions running on Scubaverse.com right now. To see what other awesome prizes you could be in with a chance of winning, click here!

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