What lies behind the familiar conger head peeping out of a crevice? Paul Naylor tells all
Ball-breaking breeding The conger does not breed in our coastal waters. It travels vast distances to spawn in deep water in the mid-Atlantic. Its body changes as it approaches the breeding grounds, with teeth falling out, gut degenerating and the gonads becoming enlarged until they account for a third of body-weight. The conger dies after spawning.
Dangerous when angry It is renowned for ferocity but a conger is more of a threat to anglers than to divers. Taking understandable exception to being hauled on to a boat, a landed conger may use its enormous strength and powerful bite to attack the nearest target. In its natural habitat, it is much more likely to be cautiously inquisitive rather than aggressive.
Born to drift A single female can produce up to 8 million eggs. Those that are fertilised develop into a larva which looks so different from the adult conger that it was once considered to be a separate species. The larva drifts back into coastal waters and then turns into a young eel.
Sleeping with the enemy The conger is a formidable predator and at night will slip out of its lair to hunt fish, including smaller congers, and large crustaceans such as crabs and lobsters. The latter are seized and often battered against rocks before being swallowed. However, this doesn't stop them sharing the crevices that congers use as their homes!
Steady on the fringe The conger eel must have the most easily recognised Latin name of any species: Conger conger. It is a highly elongated fish with a powerful snake-shaped body which has no scales. The dorsal, tail and anal fins merge to form a single fringe that runs from just behind the head round to the belly.
That's big! Congers over 2m long are quite common, while some can reach up to 3m and weigh over 60kg. An individual of 115kg (a staggering 18 stone) was once caught near Iceland.