Pascal Kobeh / Aggregation of thousands of Spider crabs (Leptomithrax gaimardii) for moulting, South Australia Basin, Australia. Pacific Ocean.

Pascal Kobeh / Aggregation of thousands of Spider crabs (Leptomithrax gaimardii) for moulting, South Australia Basin, Australia. Pacific Ocean.

Alex Mustard / 2020VISION / Leach's spider crab (Inachus phalangium) sheltering from the current beneath tentacles of Snakelocks anemone (Anemonia viridis) Selsey, West Sussex, UK, May

Alex Mustard / West Indian spider crab (Mithrax spinosissimus) shelter in a giant barrel sponge (Xestospongia muta) on a coral reef. Jardines de la Reina, Gardens of the Queen National Park, Cuba. Caribbean Sea.

David Hall / Decorator crab (Majidae) covered with hydroid polyps, providing camouflage and defensive sting. On Soft coral (Alcyonacea). Pantar, Alor Archipelago, Indonesia; November, 2006

Magnus Lundgren / Wild Wonders of China / Spider crab (Majidae sp) Xiaoliuqiu Island, Taiwan

Pascal Kobeh / Lesser / Little spider crab (Maja crispata), Canary Islands

Pascal Kobeh / Spiny spider crab (Maja brachydactyla), Sulu sea, Philippines

Shane Gross / Channel clinging crab (Mithrax spinosissimus) in a pond on Eleuthera Island, Bahamas.

Shane Gross / Channel clinging crab (Mithrax spinosissimus), Eleuthera, Bahamas.

Shane Gross / Channel clinging crab (Mithrax spinosissimus), Eleuthera, Bahamas.

Alex Mustard / Aggregation of Spider crabs (Maja brachydactyla) in shallow water in summer. These aggregations seem to be for protection (safety in numbers) while the crabs are moulting, and therefore vulnerable. Ba...