Tuesday, January 5, 2010
Saturday, July 19, 2008
Friday, July 18, 2008
Hello again are you hearing a musical chirping noise outside if you are you are listening to a musical sounds of the cicada. There are about 2,500 speices of cicadas around the world. Cicadas are not considered pests nor do they bite, sting, or harm humans. The largest cicadas are in the genera Pomponia and Tacua.
There are some 200 species in 38 genera in Australia, about 450 in Africa, about 100 in the Palaearctic and exactly one species in England, the New Forest cicada, Melampsalta Montana, widely distributed throughout Europe. There are about 150 species in South Africa. The adult insect, sometimes called an imago, is usually 1 to 2 inches long, although some tropical species can reach 15 cm.Male cicadas have loud noisemakers called "timbals" on the sides of the abdominal base. Their "singing" is not the stridulation (where two structures are rubbed against one another) of many other familiar sound-producing insects like crickets: the timbals are regions of the exoskeleton that are modified to form a complex membrane with thin, membranous portions and thickened "ribs". Contracting the internal timbal muscles produces a clicking sound as the timbals buckle inwards. As these muscles relax, the timbals return to their original position producing another click. The interior of the male abdomen is substantially hollow to amplify the resonance of the sound. A cicada rapidly vibrates these membranes, and enlarged chambers derived from the tracheae make its body serve as a resonance chamber, greatly amplifying the sound. They modulate their noise by wiggling their abdomens toward and away from the tree that they are on. Additionally, each species has its own distinctive song.When the eggs hatch, the newborn nymphs drop to the ground, where they burrow. Most cicadas go through a life cycle that lasts from two to five years. Some species have much longer life cycles, the Magi cicada goes through a 17- or occasionally 13-year life cycle. These long life cycles are an adaptation to predators such as the cicada killer wasp and praying mantis, as a predator could not regularly fall into synchrony with the cicadas. Both 13 and 17 are prime numbers, so while a cicada with a 15-year life cycle could be preyed upon by a predator with a three- or five-year life cycle, the 13- and 17-year cycles allow them to stop the predators falling into step.
Wednesday, July 16, 2008
Tuesday, July 15, 2008
Good morning today I will be talking to you about the Arapaima! It is found in south America and it is the LARGEST tropical freshwater fish in the world. The Arapaima is found in the Amazon river. They can grow up to 9.8 feet and weigh up to 440 lbs.