There are no animals that have 4 knees. All quadruped mammals have 2 knees at their back legs and then elbows and wrists at the front.Continue Reading
There is a common misconception that elephants are the only animals that have 4 knees, but elephants are the same as all other quadruped mammals, like horses and dogs, in that they have knees only in the back legs. Skeletal images clearly depict that the front leg joint bends in the same way as human elbows rather than knees. In animals like the horse, the front joint that looks like a knee is more appropriately compared to a human wrist, making the long lower leg more comparable to the third metacarpal of a middle finger. All mammals' skeletal structures are very similar due to the fact that they descend from common ancestors.
In addition, all tetrapods, which are all vertebrates with 4 limbs, and those animals whose ancestors had 4 limbs like snakes are also based on similar structures. These common limbs all share 2 long bones that combine tarsal bones in the back and carpal bones in the front. All of these limbs also have 5 digits. Even in animals that have less than 5 digits, the 5 digits are present in embryonic state.Learn more about Zoology
Several species of animals are color blind or see muted colors, including dogs, cats, bulls and sharks. Many fish can see muted colors.Full Answer >
Plants and animals are classified based upon their prevailing characteristics and traits. Biological organisms with similar characteristics are placed in the same group. The order of classification goes from the kingdom of the biological life form down to the genus and species of the organism. The five kingdoms are animals, plants, protists, fungi and moneran.Full Answer >
The many types of animals calling the Amazon River home are the Amazon River dolphin, giant sea otter, piranha, Amazon manatee, giant Amazon River turtle and electric eel, among many more. The Amazon River serves as a home to more than 2,500 species of fish, along with numerous other mammals, amphibians, snakes and plants. The Amazon River classifies as the longest in the world, and boasts the greatest biodiversity of all global rivers.Full Answer >
Desert animals have adapted ways to either bear or avoid the heat and sun, as well as store, obtain or endure the loss of water in their harsh environment. Heat, sunlight and a lack of water are the major issues most organisms face in desert environments, although there are several deserts which are actually quite cold. Water is crucial to all life, however, and its lack defines deserts.Full Answer >