A group of over 75,000 living species, these species are divied up into three main groups; vertebrates, tunicates, lancelets. Most of the animals in this phylum are amphibians, birds, reptiles, mammals, and fish. The king cobra also has the same phylum as humans. Chordates are bilaterally symmetrical, which means there is a line of symmetry that divides their body into halves that are roughly mirror images of each other. Bilateral symmetry is not unique to chordates.
The key characteristics of chordates include:
Chordates are divided into the following taxonomic groups:
Lancelets (Cephalochordata) - There are about 32 species of lancelets alive today. Members of this group have a notochord that persists throughout their entire life cycle. Lancelets are marine animals that have long narrow bodies.
Tunicates (Urochordata) - There are about 1600 species species of tunicates alive today. Members of this group include sea squirts, larvaceans and thaliaceans. Tunicates are marine filter-feeders, most of which live a sessile life as adults, attached to rocks or other hard surfaces on the seafloor.
Vertabrates (Vertebrata) - There are about 57,000 species of vertebrates alive today. Members of this group include lampreys, mammals, birds, amphibians, reptiles and fishes. Vertebrates have a vertebral column in which the notochord is replaced by multiple vertebrae that form a backbone.
The key characteristics of chordates include:
- notochord
- dorsal tubular nerve cord
- pharyngeal pouches and slits
- endostyle or thyroid
- postnatal tail
Chordates are divided into the following taxonomic groups:
Lancelets (Cephalochordata) - There are about 32 species of lancelets alive today. Members of this group have a notochord that persists throughout their entire life cycle. Lancelets are marine animals that have long narrow bodies.
Tunicates (Urochordata) - There are about 1600 species species of tunicates alive today. Members of this group include sea squirts, larvaceans and thaliaceans. Tunicates are marine filter-feeders, most of which live a sessile life as adults, attached to rocks or other hard surfaces on the seafloor.
Vertabrates (Vertebrata) - There are about 57,000 species of vertebrates alive today. Members of this group include lampreys, mammals, birds, amphibians, reptiles and fishes. Vertebrates have a vertebral column in which the notochord is replaced by multiple vertebrae that form a backbone.