30-2 Fishes

Cartilage

• Strong connective tissue that supports the body and is softer and more flexible than bone.

Atrium

• Upper chamber of the heart that receives and holds blood that is about to enter the ventricle.

Ventricle

• Lower chamber of the heart that pumps blood out of the heart.

Cerebrum

• Area of the brain responsible for all the voluntary activities of the body.

Cerebellum

• Region of the brain that coordinates body movements

Medulla oblongata

• Area of the brain that controls the functioning of many internal organs

Lateral line system

• Sensitive receptor system that enables fish to detect gentle currents and vibrations in the water.

Swim bladder

• Internal gas-filled organ in many bony fishes that adjusts their buoyancy.

Oviparous

• Term used to refer to animals whose eggs hatch outside the mother’s body.

Ovoviviparous

• Term used to refer to animals whose young are born alive after developing in eggs inside the mother’s body.

Viviparous

• Term used to refer to animals that bear live young that are nourished directly by the mother’s body as they develop.

Key Concept

• Fishes are aquatic vertebrates; most fishes have paired fins, scales, and gills.

Key Concept

• The evolution of jaws and the evolution of paired fins were important developments during the rise of fishes.

Key concept

• Adaptations to aquatic life include various modes of feeding, specialized structures for gas exchange, and paired fins for locomotion.

Key concept

• When you consider their basic internal structure, all living fishes can be classified into three groups: jawless fishes, cartilaginous fishes, and bony fishes.