American bullfrog
American Bullfrog (Rana catesbeiana )
The North American bullfrog ( Rana catesbeiana; Synonym: Lithobates catesbeianus ), also called American Bullfrog, is originally a North American amphibian species from the family of the Real frogs.
Features
The North American bullfrog is a very large, powerful Froschlurch, which can reach a head -body length of up to 20 centimeters. Striking in comparison to other rights frogs is also his big drum which is the double eye diameter in males. On the back of small warts are scattered. The dorsal color varies from olive green, gray and brownish, often with irregular dark spots; the head is often bright green. In contrast to European water frogs (see Marsh Frog, Pool Frog, Frog Pond ) are missing the bullfrog spinal glands strips and a central spine strip, and the males paired lateral vocal sacs. The belly is whitish with faded gray mottling or marbling, throat cream, yellowish in males. The males have dark pigmented during the mating season Bruns sealed Wielen. Your unpaired vocal sac is throat constantly. The thus generated, deep, grunting individual sounds ( " brr - oam " ) are used as mating calls and are widely heard.
Reproduction
The spawning season of the bullfrog correlated with water temperatures of at least 17 to 21 ° C; in the southern United States is usually from February to October of the case. The courting males exhibit territorial behavior towards competitors. The Amplexus verpaarter animals shall be, as with all "modern" anurans ( Neobatrachia ) axillary instead. The females give birth to large spawning bales from 10,000 to 25,000 eggs dark out, the drive as a " pancake " on the water surface. The development of tadpoles takes on the northern edge of its range of up to three years in extremely long. But in southern, warmer regions they require only a few months to go ashore. Mature larvae are about 11 to 14 inches tall, metamorphosed young frogs 2.5 to 6 inches.
Habitat, lifestyle and dissemination
This type of bullfrog populated riverside, lakes, larger ponds and pools, but also rice fields. A dense riparian and aquatic vegetation is preferred. Bullfrogs are mainly nocturnal. To their food range includes other amphibians, various insects, slugs, and helicid slug and sometimes chicks of various water birds, small mammals and young water snakes.
Originally, the bullfrog comes from the eastern and central North America (United States, Canada, Mexico). In the western United States, he was artificially settled. In many other areas the species was introduced by man as neozoon, as in Cuba, Puerto Rico, Jamaica, Hispaniola (Haiti, Dominican Republic), Hawaii, Japan, China and Taiwan. Also in Europe the big frog was brought, among other things, to the UK, Germany (see below), in the Netherlands, Belgium, France, Greece and Italy. Especially in Italy, the bullfrog was able to establish permanent and larger area since the 1930s, especially in the Po Valley and around Rome.
Threat than neozoon
Due to their sheer size and the fact that bullfrogs eat anything they can catch, they represent as neozoon a serious threat as a predator and competitor for food Represents the particularly applies to other amphibian species that share the habitat with them. The spread in Europe will be promoted through on the pet trade sometimes targeted tadpoles are offered, which are intended for garden ponds, where they will not remain as frogs though. In Germany appreciable populations have built up especially in the Altrheinauen the Upper Rhine Plain. However Unusually large tadpoles do not necessarily come from the bullfrog: The spadefoot, the midwife toad and the various water frog species bring forth very large larvae. Adult animals could be mistaken for those with older copies of Seefrosches in which a back line may be absent. Another threat to native species of amphibians may be in the introduction of the chytrid fungus ( Batrachochytridium dendrobatidis ) which is partly responsible for the worldwide amphibian extinction crisis.