Question

Give the general characteristics of the vertebrates and list the distinguishing features of the classes under it.

Answer 1

All vertebrates are characterised by the presence of a vertebral column. In vertebrates, the nerve cord is surrounded and protected by the vertebral column.

Complete answer:
Vertebrates are the group of animals that possess a backbone or vertebral column. They include birds, fish, reptiles, mammals, etc. Vertebrates also have a well-developed brain, a circulatory system with heart, a muscular mouth and a pharynx. The vertebrates are further categorised into seven classes.

1. Class Cyclostomata- These are jawless fish. They have a long body with gill slits for breathing, and a round, sucking mouth without jaws. They do not possess scales on the bodies or fins. Cranium and the vertebral are cartilaginous.
2. Chondrichthyes- These are marine animals with a streamlined body and cartilaginous endoskeleton. The mouth is ventral. Notochord is present throughout life. They have internal fertilisation and are viviparous.
3. Class Osteichthyes- It includes both aquatic and freshwater fish with bony endoskeleton. The body is streamlined. The skin is covered by cycloid or ctenoid scales. They are mainly oviparous, and the development is direct.
4. Amphibians can live in both marine and terrestrial environments. They have moist skin and lack scales. Respiration is by the gills, the lungs, and the skin. They are oviparous, and the development is indirect.
5. Class-Reptilia- They are mainly terrestrial species, and their bodies are surrounded by dry, corn-shaped skin, epidermal scales or scutes. The fertilisation is internal. They are oviparous, and the development is direct.
6. Class Aves- Aves are the class of vertebrates that are characterised by the presence of feathers and wings. All birds fall under this class. They possess beak. The forelimbs are modified into wings. They are oviparous and development is direct.
   7)Class Mammalia- Mammals are a group of animals that have skin covered with hair or fur on their body. The most unique trait of mammals is the presence of milk producing glands that is used for nourishing its young

Note: Phylum Chordata is classified into three subphyla: Urochordata or Tunicata, Cephalochordata and Vertebrata. During the embryonic stage, the members of the subphylum Vertebrata have notochord. In adults, a bony or cartilaginous vertebral column replaces the notochord.