From brilliantly colored hummingbirds to farting thrushes, birds are among the most beautiful and bizarre creatures on Earth. Animals range in size from 8.5 millionths of a metre to 33.6 metres (110 ft) long and have complex interactions with each other and their environments, forming intricate food webs. Shells of certain animal embryos such as reptiles and birds are examples of adaptation to a terrestrial environment. Some animals that can do this include large birds, such as vultures, condors, albatrosses and a few insects, such as the monarch butterfly. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million in total. Examples of land adaptation. The Birds of Paradise were largely unknown to the western world and it was only in the year 1996, when a photographer, David Attenborough, mesmerized the world with stunning images of the birds, which he had captured on a trip to Papua New Guinea. An Epic Guide to 60 Cool & Weird Animals Around the World, from unusual amphibians and funny looking reptiles to strange birds, mammals & sea animals. Bear, raccoon, crow, and human beings are examples of omnivores. Here are some further examples of how animals have made themselves adaptable to the specific environment in which they live. The study of animals is called Zoology . Gravitational gliding requires special anatomical features that allow an animal to either parachute to land safely or to steer themselves in the direction they wish to go. Omnivorous animals or omnivores (omni, all; vore, eater) are those that eat both plants and flesh of other animals. Animals are locomotive (i.e., ability to move around), heterotrophic (i.e., consume organic material as a source of food), and reproduce sexually (with the exceptions of asexual organisms).