- Scientific name: Necora puber
- Also known as: Devil Crab
- Size: Up to 9cm across the carapace.
- Distribution: Found throughout European waters.
The velvet swimming crab is a species of crab found around most of the UK are Ireland. They are sometimes inadvertently caught by anglers (who are likely to view them as bait stealing pests) and also have some commercial value, especially in continental Europe.
This species is easily distinguishable from the common shore crab by the fact that the back legs are adapted into flat paddle-like flippers to aid swimming, and the eyes are red (hence the alternative name of devil crab). They are usually brown to green in colour, although occasionally velvet swimming crabs can be found which are a brighter orange colour. It can also be covered in fine hairs giving this crab a velvet feel to the touch. The velvet swimming crab grows to a maximum size of around 8 – 9cm across the carapace. Other than its better (but still limited) swimming ability the velvet swimming crab feeds and sheds its shell in a similar pattern to the common shore crab and can also deliver a minor nip to anyone carelessly handling this species.
Distribution, Habitat and Behaviour
The velvet swimming crab is found throughout European waters. They can be found across all coastlines of the UK and Ireland in areas where there is rocky and broken ground. They are also found in offshore waters down to depths of around eighty to one hundred metres. Like most crab species they are scavengers which will scour the seabed for any forms of dead fish or other food sources they can find. Velvet swimming crabs are thought to be able to reproduce after their first year of life and live for around four to five years.
Second Species of Swimming Crab in UK Waters
There is a second species of swimming crab – the sandy swimming crab (Liocarcinus depurator), which is also known as the harbour crab. This species also has its rear legs adapted into flattened paddles in order to allow limited swimming ability. This species is generally smaller than the velvet swimming crab and can be distinguished by the series of white spots which are present on the carapace and can also sometimes be present on the legs as well.
Once seen as a pest species, velvet swimming crabs are now commercially important. The main market for this species is southern European countries, and the value of the British stocks of velvet swimming crab has increased as other countries such as France and Spain have overfished their own stocks of this species. The main method of capture is crab pots and traps. There are concerns that this species is now being caught in unsustainable numbers by UK fishermen and tighter regulation of the fishery is needed to protect stocks.