Question

Section 29.1

A.) What distinguishes craniates from all other chordates? What distinguishes vertebrates from all other craniates?

B.) Describe the invertebrate clade of chordates, Cephalochordata. Make sure to mention the defining trait. How do they obtain their nutrients? How do they reproduce?

C.) Describe the invertebrate clade of chordates, Urochordata. Make sure to mention the defining trait. How do they obtain their nutrients? How do they reproduce?

D.) Describe the difference between agnathans and gnathostomes. Give an example of each.

Answer 1

A. Question:- What distinguishes craniates from all other chordates ? What distinguishes vertebrates from all other craniates?

Sol:- Craniates have skull or cranium, so the names but all chordates(protochordates) have no define cranium or skull such as Hemichordata, urochordata etc. Chordata is a phylum but craniata is a subphylum of the phylum chordata.

Craniata such as hagfish have define skull or cranium but lack of vertebral column, and vertebrates have vertebral column ( replace of notochord).

B.Question:- Describe invertebrates clade of chordates, cephalochodata. Make sure to mention the defining trait. How do they obtain their nutrients? How do they reproduce?

Sol:- Phylum chordata, subphylum cephalochordata animals are small fish-like translucent marine, their notochord extends from the tip of the tail to the region beyond the brain, hence called cephalochordata . The body is laterally compressed and tapered at both ends with a post-anal tail. They are commonly called lancelets for the shape of the body.

Cephalochordata are microphagous animals. The food or sea soup consists of protozoans, algae, diatoms, and other organic particles. They obtains food by filtering the stream water that enters the pharyngeal cavity.

Cephalochordata sexes are separate ( dioecious). Fertilization takes place in the sea water.

Example of cephalochordata- Branchiostoma  

C. Question:- Describe the invertebrate clade of chordates, urochordata. Make sure to mention the defining traits. How do they obtain their nutriens? How do they reproduce?

Sol:- The subphylum Urochordata constitutes a unique group of animals under the phylum chordata. The notochord is confined to the tail region in the larval stage. For this characteristic feature, the name of the group is given Urochordata. Other features- a dorsal hollow nerve cord, pharyngeal slits and a post-anal tail are found in the larval stage.

Urochordata animals are microphagous animal. Food obtain by filter feeding.

Urochordates are mostly hermaphrodite, but in some species sex are separated. Fertilization is cross and external takes place in the sea water.

Example of Urochordata- Ascidia

D. Question:- Described differences between agnathans and gnathostomes. Give an example of each.

Sol:- Agnathans lack of jaw, so agnatha is also known as jawless vertebrate.

Example of Agnathans is Lamprey, Hagfish.

Gnathostomata animals possessing jaw in their mouth parts.

Example of gnathostomata are jawed vertebrates - Tiger, lion, human etc.