As of 2015, scientists are still pondering the advantages of bilateral symmetry for animals. Top among the possibilities is how this type of symmetry enables effective movement in purposeful and intentional directions for the animal, such as towards food sources or better environments, or away from danger.Continue Reading
A feature of vertebrates and some non-vertebrates, bilaterally symmetrical body structures might also favor the development of complex central nervous systems, such as the human spinal cord and its vast network of nerves funneling into the brain. Scientists also believe bilateralism might foster the development of improved sensory organs, such as eyes and ears, that help to support the intentional and focused movements of which these types of symmetrical bodies are capable.
The other main type of symmetry found in the animal kingdom is radial symmetry. Unlike a bilaterally symmetrical body, which has only one axis about which it can be equally divided, a radially symmetrical animal can be divided into equal halves along one of several axes, so long as that axis passes through the body's center. A starfish is a good example of this type.
Bilateral symmetry first appeared in the fossil record some 550 million years ago, exhibited by a creature called an acoel. Only a few animals have body structures that exhibit no symmetry, the main example being sea sponges.Learn more about Zoology
Characteristics common to all vertebrates include bilateral symmetry, two pairs of jointed appendages, outer covering of protective cellular skin, metamerism, developed coeloms and internal skeletons, developed brains, vertebrae and sensory organs. Vertebrates also have respiratory systems, closed circulatory systems, genital and excretory systems and digestive tracts.Full Answer >
Organisms of all types are classified to make it easier to identify species of plants and animals, to help sort and track similarities and differences between different parts of various kingdoms and to help scientists determine the relationships between currently known species and new ones. Modern scientists use these classifications to help understand species, both new and old. It allows them to be able to link the current evolution of a species to its ancestors and perhaps predict what changes could come in the future.Full Answer >
Although not every species in existence has been specifically studied for sleep patterns, scientists generally agree that all organisms need to sleep in some fashion. Sleep patterns differ from species to species, though, making a definitive answer next to impossible.Full Answer >
Rhinoceros vipers, which are known to scientists as Bitis nasicornis, are sedentary pit vipers that hail from the forests of central Africa. These snakes are primarily associated with forest pools and low-lying areas that are subject to frequent floods. Rhinoceros vipers are “true vipers” that lack the facial pits common to the pit vipers of North America and Asia.Full Answer >