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.
Chiggers are tiny arachnids that are known for delivering bites that itch intensely. Find out how chiggers work and learn about the chigger reproduction cycle.
Wolf is a doglike mammal of the Northern Hemisphere. The wolf has a broad head with a long muzzle, slanted eyes is and erect ears.