When working at zoological parks, zoologists often supply material for graphic displays at the parks' exhibits. Much of the material explains the anatomical functions of an animal and how large it grows in the wild. Most displays have approximate heights and weights. Also, all animals have physical characteristics which distinguish them from other species or subspecies. For example, Sumatran tigers have white spots on the back of their ears; these spots act as false eyes to prevent predators from attacking the tiger from behind. Also, the alligator snapping turtle -- the largest freshwater turtle in North America -- has spines on its shell and weigh up to 175 pounds.
Many of earth's wildlife species are threatened or endangered, meaning they have small populations and are on the verge of extinction. Some zoologists work for conservation groups whose aim is to raise awareness for these species' preservation. Zoologists may report the actual population of threatened or endangered species and the reasons for their status. Habitat loss, deforestation, water degradation and overhunting are causes for endangerment; most of these causes are man-made. Some conservation groups raise awareness for certain species such as the Snow Leopard Trust and Panthera, while other groups -- International Union for the Conservation of Nature and Species Survival Plan -- provide information for more than one species.
When writing about wildlife, zoologists often include descriptions of the species' habitats or environments. All forms of habitats fall under an ecosystem category such as freshwater, savannah, marine, wetlands, riparian -- or river surrounds -- mountain and urban area. Zoologists usually write about the aspects only of ecosystems that are advantageous to wildlife species. Among these aspects are the ecosystem's food chain, life cycles of animals in the ecosystem and how these environments provide shelter and nesting sites. However, zoologists also describe how pollution and urban development take a toll on ecosystems and their native animals.
Taxonomy is the scientific classification of all living organisms; this classification system comprises six kingdoms. Kingdom Animalia represents all wildlife organisms, including human beings. The history of taxonomic classification dates back to the 18th century, when Carl Linnaeus established the first classification system. Modern zoologists mention scientific names -- the animal's genus and species identification -- when writing zoological articles or essays. When a new species is discovered, zoologists are able to give it a scientific name and determine which species it is related to in the classification system.