Author:
Qjure
Book:
Qjurious
Type:
Info
Chapter:
4-500.00.00
Chordata
Introduction
Chordata are almost equal to Vertebrata and Deuterostomia.
Zoology
They have a bilateral body plan: a head and tail end, a front and back side.
They are are deuterostomia, meaning that the anus forms before the mouth.
They are coelomates, having a fluid-filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm.
They have a notochord, a fairly stiff rod of cartilage that extends along the inside of the body.
They have a dorsal neural tube.
They have pharyngeal slits; in some chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live.
They have a post-anal muscular tail.
They have an endostyle, a groove in the ventral wall of the pharynx; it filters food, produces mucus, transports food to the esophagus; it also stores iodine, as a precursor of the vertebrate thyroid gland.
Clades
1 Cephalochordata: Acraniata, Llancelets, 30 species.
2 Olfactores
2.1 Tunicata: Urochordata, tunicates, 3000 species.
2.2 Vertebrata: Craniata, Vertebrates, animals with backbones; 57674 species.
2.2.1 Agnatha: jawless vertebrates; 100+ species.
2.2.2 Chondrichthyes: cartilaginous fishes.
2.2.3 Osteichthyes: bony fishes.
2.2.4 Amphibia: amphibians.
2.2.5 Reptilia: reptiles.
2.2.6 Aves: birds.
2.2.7 Mammalia: mammals.