Lizards :: essays research papers

LizardsLizards belong to the class Reptilian, Scientists have said that Reptiles have been on earth for about 200 million years. Lizards make up the largest group of reptiles with more than 4,300 species around the world varying in different shapes and sizes. Lizards look very similar to salamanders but they differ from each other in numerous ways such as their dry scaly skin and have clawed feet and external ear opening. The majority of lizard are quite small have 4 legs and have a fragile tail that can regenerate when part of it is taken off. Lizards are cold-blooded or ectoderms, which essence that they depend on sources outside their bodies like the sun, to raise and maintain there body temperatures. Eating habits vary for lizards and depend upon the species. Some lizards feed only on insects such as the Iguana. On the other hand some eat rodents that roam deserts and eat eggs and small rodents and some feed on both rodents and insects. For protection many lizards subroutine their teeth to scare predators off. Lizards are demonstrate in tropical and subtropical regions within the world. Few species of lizards are found in temperate regions and none are located in arctic areas. Some lizards are terrestrial, arboreal, or semi-aquatic.Very few lizards are poisonous and use their venom as a defense. Several other species of lizards dont have a good defensive strategy and rely on mask such as the chameleon that is able to change its color according to its surroundings. Females of most lizard species lay eggs then are usually left hand to hatch on their own. How ever an insignificant amount give birth to living young such as the slowworm. Some female reptiles, mostly yard iguanas, do not need a male of their species to begin their reproductive cycle while others do need the presence of one or more males, and need to stimulate the hormone and other changes that lead to egg maturation and laying. To confuse matters more, some female reptiles, especially ch elonians, can retain sperm for many years before finally laying a fertilized egg. Most lizards are harmless and benefit humans by keeping the insect populations stable and stop over population. Some species are a source of food some are killed for their skins, but is not illegal in many countries. A coarse number of lizards are threatened by violations on their habitat.