Chordates 2BIbDF09 10/11

What are Chordates ?

More than 90% of all known chordates species have backbones (and thus are vertebrates). However, the phylum Chordata also includes three groups of invertebrates: lancelets, tunicates, and hagfishes

What are the main characteristics of Chordates ?

Chordata is the last phylum of the animal kingdom.There are four main characteristics to identify the chordates: 1. a dorsal, hollow nerve cord 2. notochord 3. pharyingeal slits 4. post-anal tail

What are the different kind of Chordates ?

Vertebrates Chordates

The first vertebrates appeared about 470 million years ago. They were jawless marine fish.

Although fewer than invertebrates, the group of vertebrates form a homogeneous set of animals with anatomical characteristics in common. They owe their name to the existence of a skeleton made of bone (or cartilage in some fish) whose essential part is the spine. All have a nervous system consisting of an anterior part, the brain, lodged in the skull, and a posterior, the spinal cord, housed in a cavity (the spinal canal) formed by all the vertebrae. They also have a circulatory system formed by the heart and blood vessels (arteries and veins), in which circulates the blood that transports oxygen for breathing.

Vertebrates are the most advanced animals and closest to the man (who is also a vertebrate). Moreover, they are almost all the useful species to man. They live in all environments, in water or on land. The first vertebrates were fish, which some species have become amphibians. The reptiles were formed from these amphibians. Birds and mammals come from reptiles.