The common sea urchin, Echinus esculentus, or edible sea urchin as it is often called, is widespread around all the rocky areas of UK coast. Despite its passive appearance, it is an active predator and is probably the most heavy grazer of sub-tidal rock surfaces. Very few encrusting animals and plants can resist the beak-like mouth of its underparts. This activity can quickly clear areas back to bare rock but unless the urchin population gets out of balance, this is not a problem because other creatures quickly settle out of the plankton and colonise this area. This is a key to maintaining the huge diversity of life in our inshore shallow seas.
In the photograph, the sea urchin has its tube feet extended. Each one of these has a tiny sucker at the end. When the sea is rough, the urchin can attach these to the rock around itself like a set of tent guy ropes so it does not get washed off its position.
North Sea - St. Abbs Marine Reserve