Phylum chordata general characters and classification
Answers
Answer:
Phylum Chordata
This phylum is probably the most notable phylum, as all human beings and other animals and birds that are known to you, fall under this phylum. The most distinguishing character that all animals belonging to this phylum have is the presence of notochord.
Chordates show four features, at different stages in their life. They are:
Notochord– It is a longitudinal rod that is made of cartilage and runs between the nerve cord and the digestive tract. Its main function is to support the nerve cord. In Vertebrate animals, the vertebral column replaces the notochord.
Dorsal Nerve Cord – This is a bundle of nerve fibres which connects the brain to the muscles and other organs.
Post-anal tail – This is an extension of the body beyond the anus. In some chordates, the tail has skeletal muscles, which help in locomotion.
Pharyngeal slits–They are the openings which connect the mouth and the throat. These openings allow the entry of water through the mouth, without entering the digestive system.
(Source – Lumen Learning)
It will surprise you but this phylum is a very diverse phylum, with about 43,000 species. Most of these organisms can be found in the subphylum Vertebrata. In the animal kingdom, this is considered as the third largest phylum.
Phylum Chordata is again divided into three subphyla. They are:
Urochordata
Cephalaochordata
Vertebrata
The first two phyla have very few species in between them. The major subphylum is Vertebrata, where you come across a variety of fishes, reptiles, birds and animals. Vertebrates have a distinguishing backbone that is made up of bone or cartilage. The brain is enclosed in a skull. There is a proper circulatory system, nervous system and a skeletal system that gives proper shape and support.
Learn more about Phylum Hemichordata here.
Subphylum Vertebrata is further divided into five classes. They are:
Pisces
Amphibia
Reptilia
Aves
Mammalia
Characteristic Features of Phylum Chordata
They are bilaterally symmetrical and triploblastic.
Chordates are coelomate and show an organ system level of organisation.
They have the characteristic notochord, dorsal nerve cord, pharyngeal slits.
Also, they have a post-anal
In this phylum, the nervous system is dorsal, hollow and single.
The heart is ventral, with a closed circulatory system.
The habitat of these animals is widespread. So we can find them in the marine environment, fresh waters as well as terrestrial environments.
Learn more about Phylum Arthropoda here.
Examples
Ascidia, Salpa, Doliolum – Urochordata
Branchiostoma – Cephalochordata
Lizards, fish, frogs, turtles, humans, parrots, elephants, gorillas – Vertebrata