Vertebrate

Vertebrates are a large group of chordates (animals with backbones) that includes mammals, birds, reptiles, amphibians, and fish. This group is characterized by having a vertebral column or spine.

Characteristics

Vertebrates share several key characteristics. They have a vertebral column, a brain enclosed in a skull, and an internal skeleton that allows for movement and flexibility. Vertebrates also have complex organ systems, including a circulatory system with a heart, and often have well-developed senses.

Classification

Vertebrates are classified into five major groups:

• Fish: This is the largest group of vertebrates, and includes both cartilaginous fish like sharks and rays, and bony fish like trout and salmon.
• Amphibians: This group includes frogs, toads, salamanders, and newts. Amphibians are semi-aquatic, spending part of their life in water and part on land.
• Reptiles: This group includes snakes, lizards, turtles, and crocodiles. Reptiles are cold-blooded and lay hard-shelled eggs.
• Birds: Birds are warm-blooded vertebrates with feathers and beaks. Most birds can fly, but some, like penguins and ostriches, cannot.
• Mammals: This group includes humans, as well as animals like dogs, cats, elephants, and whales. Mammals are warm-blooded, have hair or fur, and females produce milk to feed their young.

Evolution

The first vertebrates appeared during the Cambrian explosion, around 525 million years ago. These early vertebrates were small, soft-bodied creatures with simple backbones. Over time, vertebrates evolved into a wide variety of forms, from the tiny hummingbird to the massive blue whale.

See also

• Invertebrate
• Animal classification
• Evolution of vertebrates

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