THE GOBY FILE
A common sight is the goggle-eyed and gulping but graceful goby, says Paul Naylor
Nearly 20 species of gobies are found in UK waters, though only seven are seen regularly. They occupy a variety of rocky and sandy habitats (the picture shows a painted goby). Some share the burrows of crustaceans such as scampi, which are thought to welcome their fishy lodgers because they give advance warning of predators. Worldwide, there are more than 800 species of goby including some, the mudskippers, that can crawl around and feed on land.
Gobies can sometimes be confused with blennies but are quite different. While blennies tend to wriggle over the seabed, gobies swim with more graceful, darting movements. Unlike blennies, they have gas-filled swim-bladders to help them with buoyancy control.
Gobies will take surprisingly large prey in a single gulp. The tails of prawns or shrimps can sometimes be seen protruding from a goby's mouth. Gobies also scavenge, and painted gobies, in particular, will follow larger animals and divers to pick up any morsels they disturb.
Few animals look as unthreatening as a goby but the males are conscientious and protective fathers. They prepare a nest, guard the female while she lays her pear-shaped eggs within it, then defend the eggs zealously until they hatch. The guardian goby will try to drive off small crabs, shrimps and other scavengers, risking life and limb in the process.
Shy gobies such as the beautiful leopard-spotted goby don't tend to be caught in trawls or fish traps, so they were thought to be extremely rare until the advent of diving. Once divers were able to peer into the crevices where they live, they found them to be very common.
Characteristic features of gobies include a blunt head with bulging eyes so close together that they nearly touch. The pelvic fins (on the belly, just behind the head) are merged to form a sucker. This has only weak suction power, but helps gobies to cope with swell and currents.