Lizard vs. Newt

Difference Between Lizard vs. Newt

Lizard

Lizard, any of a large group of scaly reptiles related to snakes. Lizards are the most abundant of all reptiles and are found throughout the world in tropical and temperate areas. There are about 3,000 species of living lizards, including such well-known types as geckos, chameleons, gila monsters, iguanas, and skinks. Lizards far exceed snakes—the next most numerous reptile—in number of individuals. Except under special circumstances, snakes are something of a rarity even when one looks for them; lizards, on the other hand, seem to be everywhere in many of the warmer parts of the world.

Several features reveal the close relationship between lizards and snakes, the most important of which is the possession of two copulatory organs, called hemipenes, in the males. Many male vertebrates have no copulatory organs; some have one; but only lizards and snakes have two. Lizards and snakes are also alike and distinguishable from all other reptiles except the tuatara in having a transverse anal opening.

No single feature distinguishes lizards from snakes—not even legs, since some lizards lack limbs of any kind. However, unlike snakes, lizards usually have the following characteristics: a pectoral, or shoulder, girdle, that is, a skeletal support for the attachment of front limbs; movable eyelids; an external ear opening, an eardrum, and a middle ear cavity; and a different skull structure with more skull bones.

Lizards are also often confused with salamanders, amphibians that they sometimes superficially resemble. Salamanders, however, have an elongate or round anal opening, smooth rather than scaly skin, and no more than four fingers on the front limb, rather than the lizard’s usual five.

Lizards are extremely varied in form. There are long, slender, snakelike racers; earthwormlike burrowers; stumpy-tailed, short-bodied rock dwellers; long-tailed varieties capable of running swiftly on sand, earth, and the surface of water; lumbering monsters living on land or in trees; spiny, pancake-shaped species; slick-skinned, agile tree climbers and burrowers, and still others too varied and numerous to describe.

The lizard soon regenerates a new tail, usually shorter than the old one, but one that can again be used for escape if the need arises. The vertebrae are not regenerated, but a cartilaginous rod replaces the lost vertebrae. Species lacking the fracture plane cannot break off their tail and do not regenerate a new tail if theirs is accidentally cut off.

The tail serves yet another unusual function. Hungry lizards have been known to break off the tail deliberately and eat it or to return to the site where the tail was lost and eat any remaining parts.

Newt

Newt, any of a group of salamanders of the family Salamandridae that are at least seasonally aquatic; have compressed, flattened tails; and lay eggs in water. Newts live in or near ponds and streams in eastern and western North America, Europe and the Middle East, and India and far eastern Asia.

After hatching, young newts develop as aquatic larvae for about a month, when they metamorphose into adult form. In some species the young adults remain in the water, while in others they emerge onto land, not to return until they are sexually mature. After this some species may remain aquatic while others go back on land, returning seasonally to breed.

Category: VS  |  Tags: