Given that the Earth has experienced no fewer than six mass extinctions over the last 500 million years, the list of species that once lived but have gone extinct over the ages is vast. As of 2014, the Center for Biologi... More » Science Biology Zoology

An "extinct species" is a species of organism that can no longer be found in the wild or in captivity. A species is a classification of organisms which can reproduce successfully with one another. More »

For years, certain scientists have been trying to bring back extinct species - a process called de-extinction - but as of 2015 most have been unsuccessful. In theory, it is possible to bring back an extinct species, but ... More » Science Biology

As of 2011, there were an estimated 7.77 million species of animals on Earth, encompassing all phylums and families in the animal kingdom. This number increases to 8.74 million if non-animal species from the plant, fungi... More » Science Biology Zoology

There are many species of animals on Earth that spend the majority of their lives alone, including species of reptiles, amphibians, mammals, fish, insects and arachnids. Solitude is common in the animal world, and it may... More »

Several species of animals are color blind or see muted colors, including dogs, cats, bulls and sharks. Many fish can see muted colors. More »

Some animals that weigh at least a ton include all species of the rhinoceros, the African and Asian elephant, the Asian gaur, and the hippopotamus. Other animals that weigh at least a ton are some species of whale includ... More »