Necora puber — red eyes, velvety shell, paddle legs and a famous temper — is the reef's feistiest crab from Norway to Iberia, and a quiet kelp-forest worker.
Ask any fisherman who has hauled a creel off the west coast of Scotland or Brittany which crab they treat with the most respect, and the answer is rarely the biggest one. It is the one with the glowing garnet-red eyes, the fur-coated back, and the immediate, total commitment to fight: the velvet swimming crab (Necora puber), known on boats up and down the northeast Atlantic simply as the "devil crab." It is small beside the great edible crab, but what it lacks in size it repays in attitude — and beneath the pantomime aggression is a genuinely important reef animal, one of the kelp forest's own specialist hunters, and a slow-growing fishery species whose quiet story is a case study in how creel fisheries can work.
| Scientific name | Necora puber (formerly Liocarcinus puber and Portunus puber) |
| Group | Portunidae — the swimming crabs; the rear legs are flattened into paddle plates |
| Common names | Velvet swimming crab, velvet crab, velvet fiddler, devil crab |
| Size | Carapace width commonly 6–9 cm; occasionally around 10 cm |
| Depth range | Shallow subtidal and lower intertidal, commonly among kelp; recorded to roughly 70 m but densest in the kelp zone |
| Distribution | Northeast Atlantic from Norway to Portugal, including the western Mediterranean, the Azores and the Channel Islands |
| Diet | Predator-scavenger: barnacles, limpets, mussels, snails, smaller crustaceans and carrion |
| Identification | Blue-brown carapace with a dense velvety pubescence (fur); striking red eyes; flattened paddle-shaped rear swimming legs; white-tipped claws |
You identify the velvet crab in about two seconds once you know what to look for. The carapace is a soft blue-brown, but covered in such dense fine hair that it feels like felt — the "velvet" of the name and puber of the Latin. Set into the front of the shell are the famous red eyes, large and glowing garnet under torchlight or camera flash. Along the flanks the carapace carries sharp teeth, and the rear pair of legs end in flat, rounded paddles — the membership badge of the portunid family and the machinery that lets this crab break from cover and swim, like its blue-swimming relatives on other coasts, with a sideways skittering stroke.
At close range the animal seems built as much for display as for combat: when disturbed it does not flee far but turns, raises both white-tipped claws wide, and advances with the bristling self-belief of an animal three times its size. A gloved finger is fair game. See one among the dappled light of a Cornish kelp fringe and you will understand why divers remember it: the fur, the eyes, the quick sideways gravity of it.
Of all the common crabs on the northeast Atlantic reef, the velvet swimming crab is the one most thoroughly at home in the kelp zone itself. It lives among the holdfasts and the understory, hunting over the rock and through the short turfs below the canopy, at depths that keep it in the company of ballan wrasse and the sea urchins of the European shore. Its paddle legs are not an affectation: a velvet crab surprised in the open will hurl itself sideways across a reef gap with real speed, something a shore crab simply cannot do.
Its feeding is opportunistic but effective. The claws are strong for the crab's size and neatly toothed; the animal works barnacle plates, prises limpets, worries mussels from their byssal threads, and turns over the understory for whatever the canopy has hidden. Scavenging is a substantial part of the diet too — a creel baited for fish will very often pull up crammed with velvet crabs, which is how most fishermen know them best. On a healthy reef it is a mid-level processor: predator on the small, prey for the big — including octopus, large wrasse and the heavier gadoids — and a member of that broad invertebrate guild that keeps the reef's smaller grazers and its carrion in motion. The kelp forest food web would be poorer, and messier, without it.
The velvet crab supports modest but real creel fisheries, principally in Scotland, Ireland, Wales and parts of north Spain and western France, where it is sold mainly into continental markets that value it as nécoras. For decades its story was the standard tragedic small-fishery one: a slow-growing, long-lived, nearshore crab fished by unselective pots, with landings that cycled and local depletions in the hardest-worked grounds.
What makes the Scottish velvet crab interesting is the way the fishery has been quietly reformed over the past twenty-five years: minimum landing sizes carved out through negotiation; escape gaps in creels; in some areas, local management and voluntary restraint by the creelers themselves, whose own long-term interest in the same grounds has become the fishery's real protector. Compared with the fully industrialised end of European fishing, the velvet crab's story is one of the better-managed small crustacean fisheries — twenty years of data showing that a low-capital creel fishery on a slow reef animal can be run sustainably when the fishermen who set the gear are also the ones who write the rules. This is precisely the small-scale, tenure-based model we advocate in our solutions for fisheries.
Its reputation for aggression obscures the animal that divers actually meet. Unthreatened, on the open reef at dusk — when it does much of its real hunting — the velvet crab is an active, questing forager, paddle-legs folded down, stalking the understory with a quick, decisive gait. Corner it, or lift it from a creel where it has spent half a day climbing over its rivals, and you get the famous display: red eyes blazing, velvet fur bristling, both claws up and advancing — a posture that has emptied more than one inexperienced hand.
It is also a good lesson in why crab size is not the whole story on a reef. Ten centimetres of velvet crab will never matter as biomass, but its daily work — the grazed barnacle plate, the winkled limpet, the scavenged dead fish — is part of the processing power that keeps the kelp forest's understory turning over. A reef with its crab community intact is a reef with its middle management still on shift.
For its red eyes and its unhesitating willingness to fight. Hauled from a creel it goes straight to threat posture, both claws raised, and will follow through on the threat with a sharp pinch — the name is fishermen's affectionate reportage.
Yes — they are true swimming crabs (Portunidae). They can leave the bottom and move in fast, sideways bursts using the flattened rear paddles, though their everyday life is spent walking and hunting on the reef.
Yes, and it is highly valued in Spain and France (as nécoras), where it is boiled and eaten much like a small brown crab. Its small size and the local management of its fisheries mean it is rarely on British tables, but it is good eating.
Rocky kelp-bearing shores and reefs from Norway to Portugal. On snorkel or dive in the kelp zone, look along the understory at dusk or in shaded gullies. Rockpoolers occasionally find them in deep low-tide pools — approach with a stick, not a finger.
No — it is a northeast Atlantic native that stays put. The notorious invasive swimming crab stories on other coasts belong to the green shore crab and the Asian shore crab, not to the velvet crab.
No global conservation alarm exists for the species; it remains widespread and locally common. Local depletion in heavily creel-fished areas is the main concern, and is managed through landing sizes and local agreements in the better-run fisheries.
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