Chordates

What is a Chordate? These are members of the phylum Chordata. Have 4 key characteristics: a dorsal hollow nerve cord, a notochord, pharyngeal pouches, and a tail.

Hollow Nerve Cord and Notocord Dorsal hollow nerve cord runs along the back part of the body. The notochord is a long supporting rod that runs just below the nerve cord. Most chordates only have this when they are embryos.

Pharyngeal Pouches and Tail These are pair structures in the throat region. In fishes and amphibians these slits become gills. At some point all chordates have a tail that extends beyond their anus.

Most Chordates are Vertebrates 96% of all chordates are vertebrates. These animals have strong backbones. In vertebrates the dorsal, hollow nerve cord becomes the spinal cord. The backbone replaces the notochord. This is made of individual parts called vertebrate. This provides support and protection to the spinal cord.

Nonvertebrate Chordates The two groups of nonvertebrates are tunicates and lancelets. Both are soft bodied marine organisms. They have the 4 characteristics at some point in their life.

Tunicates

Lancelets These are small and fish like. They live in sandy ocean bottoms. They have a definite head region with a mouth.