• All mammals are vertebrates, meaning they have a backbone.animals image by martini from Fotolia.com
  
  Mammals are warm-blooded animals that have diverse physical features and are varied in size. Common characteristics include sweat glands, mammary glands, hair, brain development and social structure.
  
  The social structures of mammals are highly complex. Many are very similar to the hierarchies and family structures of human society. One social characteristic of mammals is that they take care of their young after birth. Female mammals provide nourishment to their offspring with the milk produced by their mammary glands.
  
  

Giraffe

• The scientific name for the giraffe is Giraffa camelopardalis.giraffe image by haemengine from Fotolia.com
  
  The giraffe is native to the Sub-Saharan region of Africa. Common habitats include savanna, open acacia woodlands, sub-tropical areas and tropical grasslands. Giraffes grow 16 to 18 feet tall and can reach speeds up to 32 miles per hour. The body weight of the giraffe can exceed 1500 pounds. It uses its hooves to as an offensive weapon.
  
  The average life expectancy of a giraffe is approximately 20 years. The major challenges to the survival of the giraffe include poaching for their tails and meat, and habitat loss.
  
  

Black-footed Ferret

• The scientific name of the black-footed ferret is Mustela nigripes.ferret image by Olga Barbakadze from Fotolia.com
  
  The black-footed ferret is a native of North America found in the Great Plains region. Its habitat is generally in short-grass and mid-grass prairies. This nocturnal mammal feeds off of prairie dogs. Adults are generally between 18 and 24 inches long. Some of the challenges that the black-footed ferret faces include disease and the gradual decrease of the prairie dog population.
  
  

Western Gorilla

• The scientific name of the Western gorilla is Goriila gorilla.gorilla image by Lucy Clark from Fotolia.com
  
  The gorilla family consists of two species, the western gorilla and the eastern gorilla. The western gorilla is found in the western lowlands of Africa. Its habitats are the primary, secondary and swamp forests. The average size of the gorilla ranges from 400 to 700 pounds. The gorilla's diet consists of fruit. Western Gorillas have a life expectancy of 40 years.
  
  The major challenges to the western gorilla's existence include the loss of habitat, the Ebola virus and natives killing the gorillas for meat.
  
  

Opossum

• The scientific name for opossum is Didelphis marsupialis.opossum-rb image by Tijara Images from Fotolia.com
  
  According to the National Opossum Society, the opossum is North America's only marsupial mammal. The mother normally carries her young in her pouch for at least three months. The opossum is about the size of a small cat, with black fur and a pointed nose. It is nocturnal, and when threatened, it will pretend to be dead.
  
  The opossum is an omnivore that eats insects, grasses, snakes, leaves and rodents. The life expectancy of a opossum is only two to four years.