Animal Kingdom

Phylum Chordata

Do you know which is the fastest animals on earth? No, it is not the Chetah. In fact, it is the Peregrine Falcon. The biggest animal is the blue whale. The three-toed sloths are said to be the slowest. All these animals fall under the same phylum, the Phylum Chordata. Let us learn more about Chordates.

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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.

Chordate features

                                (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 bran 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

Ascidia mentula

(Source: Wikipedia)

Learn more about Phylum Annelida here.

Solved Examples For You

Q: Can chordates be found in a specific kind of habitat?

Ans: We find Chordates in diverse habitats, including marine, freshwater and terrestrial habitats.

Q: Which subphylum does Branchiostoma belong to?

Ans: Cephalochordata

Q: “All vertebrates are chordates but not all chordates are vertebrates.” Justify

Ans: Vertebrata is a subphylum of Chordata. The vertebrates have a vertebral column, something like the notochord. Vertebrates show all the characteristic features of the phylum Chordata, such as the notochord, dorsal nerve cord, pharyngeal slits and post-anal tail.

But the phylum Chordata also has other two subphyla, called the Urochordata and Cephalaochordata. These are invertebrate animals but show some distinguishing attributes of Chordates, like the presence of notochord. And hence, we can say that all vertebrates are chordates, but not all chordates are vertebrates.