AT A GLANCE
- Common Name: Velvet Swimming Crab
- Scientific Name: Necora puber
- Category: Invertebrates
- Subcategory: Crustaceans
- Range: Northeastern Atlantic Ocean, from southern Norway and the British Isles south to Western Sahara, and throughout the Mediterranean and Black Seas
- Habitat Type: Rocky coastal shores, sublittoral boulder fields, kelp forests, and gravelly reefs from the low intertidal zone down to 80 meters depth
- IUCN Red List Status: Not Evaluated (assessed locally as Stable / Least Concern)
- Lifespan: 4 to 7 years
- Diet: Carnivorous/Predatory scavenger (small bivalve mollusks, crabs, polychaete worms, brittle stars, and brown seaweeds)
- Average Size/Weight: Carapace width 6 to 10 cm; weight 150 to 300 g
- Key Defining Feature: Carapace densely covered in a fine velvety brown down, flashing fierce ruby-red eyes and flattened paddle-like hind legs tipped with blue
Overview
The Velvet Swimming Crab (Necora puber), widely known among coastal fishermen as the ‘Velvet Crab’ or ‘Devil Crab,’ is a fierce, athletic, and highly pugnacious marine decapod crustacean native to the rocky coastlines of Western Europe. Belonging to the swimming crab family Portunidae, it is easily distinguished by the soft, velvet-like coat of microscopic hairs covering its shell, menacing bright scarlet-red eyes, and flattened paddle-like hind legs. Renowned for its explosive aggression, it will boldly raise its sharp, blue-highlighted claws and charge when threatened, rather than retreating like other crabs.
Biology and Physical Characteristics
Necora puber has a broad, relatively flat carapace characterized by eight to ten sharp, saw-like teeth along the front margin between the eyes. The entire dorsal surface of the carapace and walking limbs is covered in a dense, felt-like pile of short setae (hairs), giving the crab a soft, velvety texture and a rich dark chocolate-brown or reddish-brown hue. Its eyes are a startling, vivid ruby-red. The chelipeds (claws) are large, powerful, and armed with sharp serrated edges, highlighted with brilliant azure-blue stripes on the joints. Its fifth pair of pereiopods (hind legs) are modified into flattened, oval swimming paddles that enable high-speed sculling through the water column.
Behavior and Ecology
Unlike typical shore crabs that crawl slowly along the bottom, the Velvet Swimming Crab is an agile, high-speed swimmer capable of launching itself into the water column to pursue small fish or escape predators like octopuses and conger eels. It is a formidable predator, using its crushing claws to crack open bivalves and juvenile crabs. Nocturnal and secretive during the day, it shelters beneath boulders or inside deep rock crevices, emerging at night to patrol kelp beds. It is notoriously irascible: if cornered in a tidal pool, it rears onto its hind legs, spreads its blue-lined claws wide, and lunges aggressively at any intruder.
Conservation and Human Impact
The Velvet Swimming Crab has not been globally evaluated by the IUCN, but regional fisheries assessments categorize it as stable. It is the target of valuable commercial pot and creel fisheries in Scotland, Ireland, France, and Spain, where its sweet, flavorful meat is highly prized in seafood gastronomy. Fisheries authorities regulate harvesting through Minimum Landing Sizes (MLS) and bans on landing egg-bearing (berried) females, ensuring sustainable exploitation rates.
Interesting Factoid
The Velvet Swimming Crab is known to fishermen as the ‘Devil Crab’ because instead of scuttling away when discovered, it stares with glowing demonic blood-red eyes, rears up, and aggressively charges forward with open claws snapping.