Chordates, members of the animal phylum Chordata, which includes all mammals, birds, amphibians, reptiles, and fish. There are about 45,000 species of chordates. They are classified in four subphyla, the largest of which contains the vertebrates. All chordates share three basic characteristics. The first characteristic is a single dorsal nerve cord, which in mammals takes the form of the brain and spinal cord. The second is a flexible rod of cells called a notochord, which in vertebrates takes the form of the backbone. The third is the presence of gill slits at some stage during the development of the animal. All chordates have bilateral symmetry.
Pets are a great way to teach children responsibility and how to be aware of the needs of others. But different pets work better in different households. How do you know if your family needs a dog or a hermit crab?
Having some basic at-home health care skills can be a lifesaver for your cat. And an emergency is no time to start learning feline first aid. Learn home remedies for your cat.