is even more intriguing than the moult . It is also hard to catch them at it and I have only managed to film it twice . On so many occasions , I have spotted a crab near the limit of visibility doing a little decorating but then , as I draw close with camera poised , it stops and wanders off . The first successful occasion was when all the crabs in a heap after moulting were busily adorning their new suits of armour , as if they had gained the confidence to be watched from all their colleagues doing the same thing !
The second time was when a supremely assured female crab was happy to sit close to my camera and go through the procedure of attaching pieces of seaweed to the back of her carapace , before moving on to the front edge of it around her eyes and then her legs . She also showed us something we hadn ’ t noticed before , as she painstakingly ‘ chewed ’ each fragment in her mouthparts before sticking it in place . We were initially surprised but then quickly realised how slightly shredding the seaweed would make it easier to attach . When I give presentations , it is possibly this clip that makes the biggest impression on people unfamiliar with marine life , as they see what is often assumed to be a ‘ simple ’ animal carry out such an intricate procedure .
Spider crab with an impressive garden of mixed seaweed on their carapace
Even if you don ’ t get the opportunity to see a spider crab moulting or decorating , you can marvel at their features from dry land . Next time you find what looks like a dead spider crab on the beach but is an empty moult , and after you ’ ve confirmed it isn ’ t actually a dead crab ( heavier and usually very smelly !) take a closer look . Surrounding the obvious strong spines on its carapace and all over the armour
are numerous tiny bristles shaped like hooks . They look just like the sticky part of Velcro ( so the crustaceans invented it long before we did ) and are what hold the crabs ’ camouflage in place . �
Paul ’ s photos and video clips capturing UK marine life stories are on Instagram @ paulnaylormarinephoto
Spider crabs busy decorating their armour after moulting ( still from video )
To be effective , a crab ’ s decoration must match their surroundings . This one ‘ didn ’ t get the memo
Close-up of a crab ’ s moulted carapace showing the tiny hooks to which camouflage is attached
Superbly decorated spider crab in Plymouth Sound , only the ‘ elbows ’ of their claws are obvious
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