Chordate of the three subdivisions of chordates, all have distinct skulls. They include the hagfish, which have no vertebrae. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or possibly all deuterostomes, are by their tails". Most craniates are vertebrates, in which the notochord is replaced by the vertebral column. These consist of a series of bony or cartilaginous cylindrical vertebrae, generally with neural arches that protect the spinal cord, and with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, and are therefore not regarded as vertebrates, but as members of
Really Wild Animals to do to survive in North America (I Gotta Be Wild); the second is about the places animals call home (Look Who's Moving In); the third focuses on difficulties in getting what animals want (To Get What You Want); and the fourth is about the winter season (Winter). The immense continent of Asia is explored. With such a large area to cover, this episode jumps from one place to the next. Examples include the Indonesian islands, the Arabian Peninsula, Indian jungles, and Chinese mountains. Some of the featured animals in these locations are the sea snake, the Arabian oryx, the