Propped up on its front fins, the watchful blenny proves to be a bit of an intellectual, as Paul Naylor explains
TOMPOTS & SHANNIES
There are a number of very common blenny species in UK waters. The tompot is probably the most familiar to divers but the shanny, its timid, drab relative without the head tentacles, is incredibly abundant in shallow water. Look out for it at the start or end of a shore dive.
Don't confuse blennies with gobies. Blennies have slimy skin, a single long dorsal fin and no swimbladder (a fish's BC) so they tend to wriggle across the seabed. Gobies dart around more gracefully but don't share the blennies' watchful charisma.
Blennies are good parents - or at least, the father is. The female lays her eggs in a rock crevice or old shell, but plays no further part in bringing up the children. The male stays and guards the eggs until they hatch, helping to keep them oxygenated by fanning movements, and warding off scavengers.
SHELLFISH WITH GREENS
A whole range of foods is eaten by blennies. Tompots have a great appetite for sea anemones, the stinging cells of which deter most other predators. Small shannies will nip off the feeding limbs of barnacles, while their elders munch the whole thing, all with a healthy supplement of seaweed.
BOFFS WITH ATTITUDE
Blennies are thought to be intelligent fish, and have managed to recognise colours, shapes and even different letters in learning experiments. Their distinctive faces, coupled with a habit of propping themselves up on their fins, also creates an impression of cheeky alertness.
LIVING TIDE TABLES
The shanny has a well-developed internal clock and, if kept in an aquarium, continues to get restless at precisely the time of high tide, even after many months. Shannies will sometimes hop out of the water voluntarily, and can happily spend a few hours there before returning.
Appeared in DIVER - April 2000