The following sea creatures are present in Britsh waters, although they are relativley rare and little-known to anglers and the general public alike.
Common Sea Urchin
The common sea urchin (Echinus esculentus) is species of sea urchin which is found throughout European waters and the wider northeastern Atlantic. They live on hard and rocky seabeds and can be found in waters down to around one thousand metres deep. The common sea urchin can grow to about 10cm across. It has a thin brittle shell, covered in small spines. They feed on seaweed and algae, although they will also eat invertebrates which encrust onto surfaces such as barnacles. Unfortunately, habitat destruction and deep-sea trawling mean that the common sea urchin number have been reduced and the IUCN (International Union for the Conservation of Nature) classes the common sea urchin as Near Threatened. A further threat to sea urchin numbers is that they are collected by divers due to their attractive appearance and the collectability of their undamaged shells. The common sea urchin is edible and there is a small market for it as a source of food throughout Europe.
Lightbulb Sea Squirt
The lightbulb sea squirt (Clavelina lepadiformis) is a species of sea squirt which has a fairly widespread distribution all around the coastlines of the UK and the rest of Europe. They grow to a maximum length of around 3cm and are often found together in groups or small colonies. Like all sea squirts, they are filter feeders and take microscopic food particles which flow past them in the tide. The name lightbulb comes from the fact that this species has yellow and white internal organs which are visible through its translucent body and make this species look like they glow.
Football Sea Squirt
The football sea squirt (Diazona violacea) can grow up to 30cm across. They are most common in western Scotland and Ireland, although small, dispersed populations are present elsewhere in British waters. They are also found throughout the rest of Europe. This species of sea squirt does indeed look somewhat like a football, hence the name. The football sea squirt is a filter feeder which relies on consuming microscopic matter and food particles which float past on the tide.
Gravel Sea Cucumber
Sea cucumbers are marine creatures which are so-called because of their elongated body resemblesthe edible plant of the same name. There are well over one thousand species worldwide, and all have thick skin, no visible sensory organs and a very limited ability to move.
Neopentadactyla mixta, the gravel sea cucumber, is the most common variety in British waters and is found mostly along the western coast of Britain and Ireland. As the name suggests this sea cucumber lives on heavy sand, gravel or shingle seabeds, in water down to around one hundred metres deep. It has the typical elongated body of most sea cucumber species, is usually 10 to 15cm in length, with small feet running along the body, and a protrusion of tentacles, known as a crown, which extends from one end. This species is usually white or light grey in colour. The sea cucumber buries its body into the sediment and then leaves its tentacles exposed. It feeds by catching organic matter in its tentacles as it flows pasts. Once the tentacle has caught enough food it is withdrawn into the body of the creature where the food is removed and digested. In some areas gravel sea cucumbers can be found in great numbers. Sea cucumbers go into some form of hibernation when the whole body and tentacles are withdrawn into the gravel and they do not feed for some months. The pattern and reason for this hibernation is poorly understood.
Devonshire Cup Coral
The Devonshire Cup Coral (Caryophyllia smithii) is a hard coral which is found all along the coast of Ireland and Wales and along the west coast of Scotland and south west England. It is also found throughout Europe and the Mediterranean. Devonshire cup coral are found attached to rocks and stone, in waters down to around one hundred metres deep. This species can range in colour from reddish to brown, pink, yellow or green. Tentacles emerge from the coral which are translucent in colour with spherical knobs at the end. Devonshire cup coral use these tentacles to suspension feed on minuscule sea creatures suspended in water.
Dead Man’s Fingers
Dead Man’s Fingers (Alcyonium digitatum) is a soft coral, found all around the coasts of the British Isles, as well as throughout Europe (from Scandinavia to the Mediterranean) and also in American and Canadian waters. It generally grows in thick colonies and takes on a light yellow, orange or pale yellow colour. This coral lives in shallower water (down to around fifty metres or so) where light can penetrate and algae can grow. It suspension feeds on plankton by extending tentacles into the water.
Rosy Feather Star
The rosy feather star (Antedon bifida) is a species of sea lily (related to brittle stars and sea urchins) which is fairly common around the British Isles. It is found in its highest numbers along the western coast of Scotland and is less common (although still present) around the eastern coast of Scotland and England. It can be found in depths ranging from a few metres deep, all of the way down to several hundred metres.
This species takes the form of a small disc-like body with a number of arms protruding from the edges. The colour is usually a mottled red to orange with white. The underside of the disc has around fifty tendrils coming from it, which the rosy feather star uses to cling to rocks and stone, although it can use the tendrils to ‘walk’ freely and surprisingly quickly, and have a very limited ability to swim by moving their arms to propel them through the water. They are suspension feeders and hold their arms upwards to trap sediment and plankton which they then feed on. Their arms can also be folded inwards when the rosy feather star is resting.
The lancelet also known as the amphioxus (scientific name: Branchiostoma lanceolatum) is a species which is found mostly towards the south and west of the British Isles. They are a strange animal with a slim, semi-transparent body which allows its internal organs to be visible. The usual length is 5 to 6cm. A single eye-spot is visible on the head area there is a rudimentary tail at the other end of the body. Small cirri (tentacles) are located around the mouth area. They bury themselves in sand, soft mud or light gravel seabeds and filter feed on suspended sediment or detritus which passes. As an invertebrate chordate (an animal which has no vertebrae) the lancelet is of immense interest to scientists as they are thought to be an important evolutionary step into how vertebrates evolved. In some Asian countries this species is utilised as a source of feed in aquaculture.