Gasterosteus
Three-spined stickleback ( Gasterosteus aculeatus )
Gasterosteus is a genus of sticklebacks. Their representatives colonize a wide range of habitats both in salt as well as in brackish and fresh water. They are found in much of the northern hemisphere, but not penetrate so far into Arctic regions before like the sticklebacks of the genus Pungitius. The distribution area lies along the sea coasts in the marine environment. Type species is the three-spined stickleback and Europe Terra typica.
Features
The relatively small fish in the size and aspect signage relatively variable, the differences are partly genetically determined, but are also subject to strong environmental influences. The marine and anadromous forms are taller and slimmer than pure freshwater populations in general. Before the soft-rayed dorsal fin are on bony plates along the center back three, rarely four, back spikes. The first two spines are long and strong, the rear sting is much smaller. The absolute length of the spines is subject to strong fluctuations. A further sharp sting sits on each ventral fin, respectively. The Ventralstacheln braced against the massive pelvic girdle. The latter consists of a large abdominal shield fused with each other pelvic bones (ossa pubis), whose extended wings are connected to the adjacent side and back shields. At the beginning of the anal fin is still another, shorter sting. In each case, a series of bony plates covering the sides of the body. Their greatest vertical extent they achieve in the abdominal region, the smallest shields are at the beginning of the caudal peduncle, which carries keeled plates.
Within the Gasterosteidae the Gasterosteus have indeed reduced but very efficient and robust spines formed with their signs in the number of the most effective defensive armament. This allows them to, in comparison to other members of their family, more open way of life which manifests itself, among other things by staying in poor coverage areas and a very eye-catching spawning coloration of the males.
System
At the time of its definition by Linnaeus to the genus Gasterosteus were also attributed nor the Nine -spined Stickleback and the. These two species were collected but later in the rank of its own species. The taxonomic recognition of Gasterosteus is extremely difficult. At times, more than 40 different population groups had species rank. Later, these groups were, with the exception of Gasterosteus wheat landi as conspecific merged under the "super species " Gasterosteus aculeatus. In the 1990s, some taxa were revalidisiert by Kottelat. The concomitant division of the European three-spined stickleback in a fully signposted style with marine distribution area, G. aculeatus, and a low -marked species with predominantly binnenländischem habitat in Western Europe, Gasterosteus gymnurus is rejected by Paepke. He argues that the distribution of freshwater habitats by G. gymnurus can not be reconciled with the fact in agreement that all three-spined sticklebacks have reached their habitats in the inland river systems coming through from the coast and therefore the type is polyphyletic. In common areas inhabited mate low and fully signposted form fully with fertile offspring. The also revalidisierte kind Gasterosteus islandicus considered Paepke for the same reasons as polyphyletic.
- Three-spined stickleback ( Gasterosteus aculeatus ) Linnaeus, 1758
- Gasterosteus crenobiontus † Bacescu & Mayer, 1956
- Schwarzgefleckter stickleback ( Gasterosteus wheat landi ) Putnam, 1867
Some populations that may achieve species status, are not well understood. Examples are the "white stickleback " in Nova Scotia and forms from the Azabachije lake on Kamchatka.