CROATIAN FAUNA 2007 - CRABS - NORWAY LOBSTER (SCAMP)

Norway lobster (Nephrops norvegicus Linnaeus) Norway lobster, langoustine, often called scampi when eaten, belongs to the family Nephropidae – crawfish (infraorder Astacidea, suborder Reptantia – crawfish). The animal lives in the soft sediment of the Atlantic Ocean (from Iceland on the north to Portugal and Morocco on the south), the Mediterranean and Adriatic Sea. The densest populations in the Adriatic Sea have been recorded near the island Jabuka/Poma, in the Velebit channel, in the sea of the Kvarner Bay and in Kvarnerić. They live at the depth of between 200 to 800 metres but they can also be found in shallower parts; e.g. they have been recorded to have been found at the depths of less than 20 metres in the lakes linked to the sea, the Scottish Sea Lochs. They dig burrows in the muddy bottom where they live. The burrows are 10 cm in diameter, about one meter long and enter the muddy bottom some 20 to 30 centimetres. The lobsters stay in their burrows during the day, and at sunset they come out to find some prey, their food. At greater depths, with less light, the lobsters are active during the day as well. They do not migrate and show territorial behaviour, aggressively defending their burrows. They move along the bottom walking despite being good swimmers. Norway lobster are solitary predators feeding mostly on molluscs and other crabs, but they also eat dead animals. Though they live on their own, they sometimes share the same burrow with other crabs (scampi). The density of the population depends on the physical characteristics of the bottom (depending on whether it is suitable for digging burrows), on the climate (temperature of the water and the strength of the waves), fishing in a certain area, and the like. Except being predators regarding animals smaller than themselves, they also become the prey of many fish (e.g. cod, ray and catfish). The body of the Norway lobster is slim, orange-pink in colour, elongated and flat laterally. The head and thorax are fused into a non-segmented cephalothorax, while the abdomen consists of clearly segmented carapace ending with a fan-shaped tail that helps the lobster to swim. The first three pairs of legs bear claws. The first pair of claws is very narrow and elongated and has laterally placed longitudinal spiny ridges. Their eyes are large, black and placed on mobile stalks. Females grow to 17 cm in length and males up to 25 cm. Their growth is discontinued; in a range of molting when they lose their old carapace they grow in length while soft; their carapace hardens again. The increase per molting depends on many factors (water temperature, accessible food, density of population, age of the lobster), so it cannot be estimated with certainty how old the animal only is on the basis of its size; what is known is that larger individuals molt once a year and the smaller ones several times. It is known that they can even live up to the age of 15 years. They spawn once a year, usually in summer. Immediately before spawning they molt and the male impregnates the female while her exoskeleton is still soft after molting. After the eggs have been impregnated, the female carries them fastened to her swimmerets for 8 to 9 months and more or less hides in her burrow. It is a fact that out of the total number of eggs (about 1,000) larvae do not hatch from all of them; up to 32 to 51% of eggs get lost during the incubation period. The reasons are different: from badly fastened eggs to the swimmerets, the attacks of predators, disease, and the like. Larger females carry more eggs to the end of the incubation period, i.e. to the spring of the next year. Females that have not spawned have the capability to resorb their eggs into ovaries and thus recycle a great amount of nutrient matter and energy. It is also known that larger females produce more eggs so that their reproductive success is usually higher. The larvae hatch from April to June when the females leave their burrows. The larvae usually keep rather close to their parents’ populations. In the Adriatic Sea the Norway lobsters’ larvae in the plankton have been recorded in late winter, from January to April. The Norway lobster can carry various epibiotic organisms on their bodies; it is interesting that in December 1995 the commensal Symbion pandora was discovered attached to the mouthparts of a Norway lobster’s legs. In later analyses it was found that it was the first and so far the only member of a new phylum in the animal kingdom called Cycliophora. Ivana Maguire