Are elephants chordates

Answer 1

The phylum Chordata contains all animals that possess, at some point during their lives, a hollow nerve cord and a notochord, a flexible rod between the nerve cord and the digestive track. The phylum Chordata is an extremely diverse phylum, and the one most recognizable to us. The phylum contains about 43,700 species, most of them concentrated in the subphylum Vertebrata, making it the third-largest phylum in the animal kingdom. The phylum Chordata is divided into three subphylums: Urochordata (tunicates), Cephalachordata (lancelets), and Vertebrata (vertebrates). The first two phyla are very small containing only about 2,000 species total. Tunicates are marine animals that only show the attributes of the chordata phylum in the larva stage, and when they turn into adults lose the notochord and nerve cord. Adult tunicates look like small sacs around 3 cm tall attached to the ocean floor. Lancelets, which are similar in appearance to small fish, keep the nerve chord and notochord into maturity but are extremely simple in structure and lack a backbone. The third phylum, vertebrata, is the most important, and is distinguished by a backbone (made either of bone or cartilage) containing interlocking vertebrae and a skull enclosing a brain. These two features serve to protect the entire central nervous system, and in addition give support and structure to the body; these bones also form part of a larger system of bones, the endoskeletal system. Unlike the exoskeleton of other phylums such as the arthropods, which must be shed periodically, this endoskeleton is permanent and can grow with the organism. This endoskeleton gives vertebrates a competitive edge over all other animals, as it can easily be scaled for use in large organisms, and it allows these organisms to be relatively light and fast-moving. In comparison, most organisms with an exoskeleton are small and slow-moving, due to the limitations of their large and bulky skeletal system.