Dog
dog, (Canis lupus familiaris), domestic mammal of the family Canidae (order Carnivora). It is a subspecies of the gray wolf (Canis lupus) and is related to foxes and jackals. The dog is one of the two most ubiquitous and most popular domestic animals in the world (the cat is the other). For more than 12,000 years it has lived with humans as a hunting companion, protector, object of scorn or adoration, and friend.
Frequently the terms rabbit and hare are used interchangeably, a practice that can cause confusion. Jackrabbits, for instance, are actually hares, whereas the rockhares and the hispid hare are rabbits. Rabbits differ from hares in size, life history, and preferred habitat. In general, rabbits are smaller and have shorter ears than hares. They are born without fur and with closed eyes after a gestation period of 30–31 days. They prefer habitats composed of trees and shrubs, where they live in burrows dug into the soil. Hares, in contrast, are larger in size, and they are born fully developed with fur and open eyes after a gestation period lasting about 42 days. They prefer open areas such as prairies, where they make their nests in small open depressions.
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Around 99% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with over 95% belonging to the teleost subgrouping.