The lumpsucker’s name really says it all: it is covered in bony plates that stick out as hard lumps, and it has a sucker disc on its belly. With its warty skin it is a rather grotesque-looking fish. It has a deep, rounded body, high crest on the back and small rounded dorsal and anal fms with a broad tail fin.
The pectoral fins are fan-like and stretch from behind the gill cover to underneath the throat where they join the large, rounded sucker-like disc on the belly. All the fins have thickened rays, and the fin membranes are fleshy – as if filled with jelly. The skin is scaleless but the lumpsucker has seven rows of large, prickly, bony plates running from the head to the tail; the single row on the top of the back adds to the crest-like appearance.
In colour the lumpsucker is bluish-grey or greeny brown on top, and paler beneath. Males develop a reddish or orange colour- ing over the belly and up the sides in the breeding season. Young fish are green.
Common on the northern coasts of Britain, it is found both close in to the shore and out to sea. It has always been regarded as a bottom-living fish – it uses the powerful sucker disc on its belly to cling firmly to rocks, especially when the tide brings waves surging in. However, it also lives in mid water in large numbers, although mainly in the northern North Sea, off the Faeroes and off Iceland.
Many lumpsuckers migrate towards the shore to spawn. Clumps of pink or yellowish eggs are laid near seaweed stalks and in crevices in rocks near the low-tide mark between February and May.
The egg mass is guarded vigorously by the male fish, who drives off potential predators and fans the eggs to provide them with the well-oxygenated water essential to their survival. At low spring tides these brooding males can be exposed to the air as the tide falls and frequently fall prey to gulls and crows. Otters on the western Scottish coast also prey on them, and it’s likely that seals capture them too. Lumpsuckers in the open sea are caught by oceanic fishes – and by sperm whales.
After hatching, the young fish live in the surface waters of the sea for a short while but drift gradually towards the shore. As one might expect, they are nearly spherical, but the ventral sucker disc is well developed. They are frequently found attached to floating seaweed and, at a length of about 2cm (%in), can be found on brown or green seaweed on the shore. They are wonderfully adept at matching their colour to that of the plant, and those on green seaweed can look like brilliant emeralds once they are dislodged into the water.
The lumpsucker is not a commercially important species, but some are caught for their roe, which is sold as a kind of substitute for caviar. Anglers fishing rock marks occasionally catch them accidentally.
Not much is known about the lumpsucker’s diet. Young fish may eat small crustaceans, and the larger ones feed on worms and small fishes. However, research has shown that they eat sea gooseberries and jellyfish, and it may be that this is a regular diet, although it’s difficult to prove since these animals have no hard parts that can be recognized in the fishes’ stomach contents.