Answer to Question #267699 in Zoology for Jess

Question

1.     Chordates are the most advanced Phylum in the Animal Kingdom, including all vertebrates, animals with backbones, and several invertebrates. They possess a bilaterally symmetrical body and are deuterostomes.

 In your essay;

i.          Discuss five (5) distinguishing characteristics of Chordates.

ii.        Differentiate between Urochordates and Cephalochordates.

iii.      Briefly discuss the phylogeny of Vertebrates.

Answer 1

Characteristics of Chordata. Animals in the phylum Chordata share five key chacteristics that appear at some stage during their development: a notochord, a dorsal hollow (tubular) nerve cord, pharyngeal gill arches or slits, a post-anal tail, and an endostyle/thyroid gland.

The main difference between Urochordata and Cephalochordata is that Urochordata consists of a notochord extended in the head region whereas Cephalochordata contains the notochord in the posterior region of the body.

Vertebrates (backboned animals) are part of the wider group Chordata (see Phylogeny and Evolution of Chordates), characterized by the possession of an axial stiffening rod (notochord), a perforated pharynx, a dorsal hollow nerve cord, and a post-anal tail.