Thursday, 3 January 2013

Facts about Bullfrog



The American bullfrog (Rana catesbeiana or by some authorities as Lithobates catesbeianus) often simply known as the bullfrog in Canada and the United States, is an aquatic frog, a member of the family Ranidae, or “true frogs”, native to much of North America. This is a frog of larger, permanent water bodies, swamps, ponds, and lakes, where it is usually found along the water's edge.



They grow on average to be about 3.6 to 6 in (9.1 to 15 cm) in body length (although there are records of some up to 8.0 in (20 cm)), legs add another 7 to 10 in (18 to 25 cm) to length. Bullfrogs go from 5 to 175 g (0.18 to 6.2 oz) on average in the first 8 months of life. Large mature bullfrogs can weigh up to 500 g (1.1 lb), with exceptional ones attaining 800 g (1.8 lb)

Feeding

Bullfrog stomachs have been found to contain rodents, small turtles, snakes, frogs (including bullfrogs), birds, and a bat, as well as the many invertebrates, such as insects, which are the usual food of ranid frogs. The specialized ability of bullfrogs to capture submerged and large, strong prey comprises a pronounced biting motor pattern that follows up on the initial and typical ranid tongue strike. Adaptation to target image displacement due to light refraction at the water-air interface consists of the bullfrog's application of tongue surface comparatively posterior to the perceived location of the prey target.


Human Use

While occasionally kept as pets, they will still bite even when tamed and can live up to 16 years or more in captivity. The American bullfrog provides a food source, especially in the Southern United States and in some areas of the Midwestern United States. In a few locations, they are commercially cultured in ponds, but the traditional way of hunting them is to paddle or pole silently by canoe or flatboat in streams or swamps at night; when the frog call is heard, a light is shone on the frog to temporarily inhibit it. The frog will not jump into deeper water as long as movement is slow and steady. When close enough, the frog is gigged and brought into the boat. In some states, breaking the skin while catching them is illegal, and either grasping gigs or hand capture are used. The only parts eaten are the rear legs, which resemble small chicken drumsticks and, sometimes, the backs, which are usually fried.

  • The American bullfrog is also used as a specimen for dissection in many schools across the world.
  • The American bullfrog has been introduced to many countries and regions in the world, such as South Korea, Western Europe, Brazil, Colombia, and Australia, where it has become a nuisance to those countries' natural ecology because of its appetite. They are sold in China for eating.
  • The American bullfrog has been widely introduced to most western states, and is now very common there, especially in California, and poses a serious threat to native species, such as the California Red-legged Frog because bullfrogs are aggressive and will eat anything smaller than themselves. They are considered a factor of the red-legged frogs' decline.



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