Mary Allen
Because of its stocky body shape, the sea hare is also called a “lump”.
Characteristics
What does a sea hare look like?
Its plump body and bony protuberances on the back and sides make the lumpfish look a bit like primeval fish. Sea hares belong to the flat-bellied family. This name comes from a peculiarity: As with the other members of this fish family, sea hares have developed a sucking disc from their pelvic fins. With it, the animals can attach themselves to the ground and stones, so that even heavy seas and strong currents do not harm them.
The males of the lumpfish are about 30 to 40 centimeters long, the females up to 50 centimeters, in rare cases even up to 60 centimeters. They usually weigh up to five kilograms and very large animals up to seven kilograms.
Males and females also differ significantly in color: the females are gray-blue to greenish in color, and the males are dark gray to brown. Their skin has no scales; it is quite thick and leathery. Also, lumpfish don’t have a swim bladder.
It was regressed because they rarely live in deeper water and swim only a little: they usually sit firmly attached to the bottom. During the breeding season – also known as the spawning season in fish – the belly of the male turns red. The dorsal crest, developed from the dorsal fins and covered with thick skin, is higher in females than in males and their pectoral fins are smaller.
Where does the lumpfish live?
Lumpfish are found in the North Atlantic, North Sea, and Baltic Sea. However, lumpfish from the Baltic Sea is significantly smaller: these females only grow up to 20 centimeters long, the males up to 15 centimeters.
Sea hares live at depths of 20 to 200 meters in the sea. There they prefer places with rocky, hard bottoms where they can attach themselves well with their suction disc. You can only occasionally find them in the open sea.
What species of lumpfish are there?
There are about 25 different species of lumpfish. They all live in the cold seas of the Earth’s northern hemisphere.
Behave
How do sea hares live?
Sea hares lead relatively quiet lives. These fish are rarely seen swimming in the open sea or in deeper water. They prefer to live in relatively shallow water near the shore. Only in winter do they retreat to deeper water. Sea hares are loners, only now and then you will find several animals together.
They are very well adapted to life in coastal waters, where there is usually strong surf: Thanks to their suction disc, they can hold on to the bottom, so that heavy seas and strong currents cannot harm them. So firmly attached, they lie in wait for their prey. In doing so, they can develop an amazing strength: To detach a sea hare that is only 20 centimeters long from its ground, you need a force of about 36 kilograms!
Friends and foes of the sea hare
The biggest enemies of lumpfish are seals, which particularly like to eat this fish. But humans are also enemies of the lumpfish: male lumpfish are popular as food fish in northern countries. However, the males are usually only eaten when they are reddish in color because they taste better then. In Iceland, for example, dried lumpfish meat is considered a delicacy. About 10,000 tons of lumpfish are caught and sold every year.
The females do not taste as good and are rarely eaten. However, they are coveted for their eggs, the roe. These lumpfish eggs are often dyed black and sold as so-called German caviar. About 700 grams of roe can be obtained per animal. The real caviar, on the other hand, consists of the eggs of the sturgeon, a fish that today lives mainly in Russian and Asian rivers and in the adjacent seas.
How does the lumpfish reproduce?
Springtime, from February to May, is the spawning season for sea hares. Then thousands of fish move into the Wadden Sea to lay their eggs in the shallow water.
Each female then lays up to 350,000 eggs in large clusters of around 100,000 eggs each. These spawning balls are laid between the algae on stony soil and stick to the ground. The eggs are initially yellow-red in color and later turn greenish. They have a diameter of about 2.5 millimeters. After laying their eggs, the females swim back into the deeper water.
The males stay with the eggs, attach themselves to a rock, fan the eggs with fresh water and protect them from spawn predators such as fish and crabs. Even at low tide, when the seabed is almost dry, the male lumpfish stay in their clutches. If a clutch is washed away by the tide, the male swims after it and guards it in the place where it lies down again.
Finally, after 60 to 70 days, the larvae, which are only six to seven millimeters long, hatch. They resemble tadpoles and remain in shallow water throughout the summer. There they cling to algae. After a year they are about 15 to 30 centimeters long and look like their parents. Then comes the time when they slowly swim into deeper water. They are sexually mature at the age of three to five years.
Care
What do sea hares eat?
Sea hares like both plant and animal food: they eat small crabs, fish, and jellyfish. Her particular favorite food is comb jellyfish. However, they also eat aquatic plants from time to time. Lumpfish larvae feed on plankton, which are microscopic plants and animals that float in seawater.
Keeping sea hares
While lumpfish are sometimes kept in zoos, they are almost never found in private aquariums.