Karthikeyan

Vertebrates

Definition

• Vertebrates are animals that possess a vertebral column (backbone).

Vertebral Column

• Also called the spinal column or spine

• Made of many cylindrical bones called vertebrae

• Vertebrae are joined end to end

• Each vertebra has a bony arch on the dorsal (upper) side

• This arch protects the spinal cord

Spinal Cord and Brain

• The spinal cord runs through the vertebral column

• The front end of the spinal cord enlarges to form the brain

• The brain is protected by the skull

• The skull usually bears a pair of jaws with teeth

Classes of Vertebrates

There are five main classes:

1. Fish

2. Amphibia

3. Reptiles

4. Birds

5. Mammals

Body Temperature Regulation

Cold-blooded Animals

• Fish, amphibia, and reptiles

• Body temperature varies with surroundings

• No internal temperature control mechanism

• Example:

  • Lizards bask in sunlight to warm up

  • Hide in shade to cool down

⚠️ The term cold-blooded is misleading — their blood can be warm in hot environments.

Warm-blooded Animals

• Birds and mammals

• Maintain a constant internal body temperature

• Have internal regulatory mechanisms

• Can remain active even in cold environments

Advantage of Warm-bloodedness

• Activity does not depend on environmental temperature

• Cold-blooded animals may become slow in cold conditions, making them vulnerable to predators