Vertebrate Animals: Features and Evolution

Vertebrates: A Major Chordate Group

Vertebrates constitute the largest group within the chordates. All vertebrates have a backbone as a structural axis, a bony support that develops around the notochord, replacing it completely in many species. The spine is composed of bony elements, the vertebrae, which surround the nerve cord along its entire length.

Five Types of Vertebrates

• Fish
• Amphibians
• Reptiles
• Birds
• Mammals

General Features of Vertebrates

In all adult vertebrates, the notochord is replaced or surrounded by a backbone made of flexible materials, cartilage, or bone.

The Skull

The brain, located at the anterior end of the spinal cord, is protected by a box-shaped structure: the skull.

Nervous System

The nervous system of fish includes the brain, spinal cord, and nerves that extend throughout the body.

Reproduction

The reproductive organs are located in the posterior region of the body, lateral to the digestive organs. The genital opening leads to the exterior immediately after the anal opening. Eggs mature in the female’s ovaries over several months.

Class Mammalia

Mammals have hair instead of scales, nurse their young, and maintain a constant body temperature (homeotherms).

Amphioxus (Cephalochordate)

The amphioxus retains the three typical characteristics of chordates throughout its life: dorsal nerve cord, notochord, and gill slits.

Evolution and Adaptation

Adaptation is the structural capacity of an organism that allows it to live and adapt to its environment. Adaptation can be structural, physiological, or behavioral.

Galapagos Island

The isolation of the Galapagos Island has allowed species to be preserved in their natural environment; otherwise, some would have disappeared. The Galapagos Island is located 900 kilometers off the coast of South America, is of volcanic origin, and probably formed 1 million years ago.

Diversity of Living Things

The diversity of living things includes size, shape, living environments, behavior, food, etc. The environments in which living things develop range from frozen polar and mountain areas to warm deserts. The variety also relates to foods and roles in the ecosystem.

Fungi

Penicillium notatum yields penicillin, the first antibiotic discovered and produced industrially, and one of the most important.

Lichen is a symbiotic association between a blue-green alga or a fungus belonging to the ascomycetes.