FishesCopyright © McGraw-Hill Education

Characteristics of Vertebrates• Animals belonging to subphylum Vertebrata have a vertebral

column and specialized cells that develop from the nerve cord.

• Classes of vertebrates include fishes, amphibians, reptiles, birds, and mammals.

FishesCopyright © McGraw-Hill Education

Characteristics of Vertebrates

Vertebral column• The notochord is replaced by a vertebral column that protects and

surrounds the dorsal nerve cord.

• Made of cartilage – flexible tough material found in skeletons, or bone

• The vertebral column functions as a strong, flexible rod that muscles can pull against during swimming or running.

FishesCopyright © McGraw-Hill Education

Characteristics of Vertebrates

Neural crest• A neural crest is a group of cells that develop from the nerve cord

in vertebrates.

• Portions of the brain and skull, certain sense organs, and some nerve fibers are some of the structures that develop from the neural crest.

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes• Fishes are found in a variety of aquatic habitats including seas,

lakes, ponds, streams, and marshes.

• Most fishes have vertebral columns, jaws, paired fins, scales, gills, and single-loop blood circulation.

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

Jaws• Anterior gill arches evolved into jaws in ancient fishes.

• The development of jaws allowed ancient fishes to prey on a larger range of animals.

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

Paired fins• A fin is a paddle-shaped structure on a fish or other aquatic animal

that is used for balance, steering, and propulsion.

• Paired fins reduce the chance of rolling to the side and allow for better steering during swimming.

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

Scales• Scales are small, flat, platelike structures near the surface of the

skin

• Ctenoid scales – made of bone and skin

• Cycloid scales – made of bone and skin

• Placoid scales – made of toothlike material

• Ganoid scales – made of enamel and bone

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

Gills• Fishes get oxygen when water that enters their mouths flows

across their gills, where oxygen from the water diffuses into the blood.

• The flow of blood in the gills is opposite the flow of water across the gills, allowing for more efficient uptake of oxygen

• Some fish protect their gills with operculum, a movable flap.

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

Circulation• Vertebrates have a closed circulatory system.

• In most fishes, the heart consists of two main chambers – the atrium, where the heart receives blood from the body, and the ventricle, where the heart pumps blood to the gills.

Blood Flow in Fish

Animation

FPOAdd link animation from page 824 (figure 8) here.

FishesCopyright © McGraw-Hill Education

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

Feeding and digestion• Ancient fishes were most likely filter feeders and scavengers.

• Most fishes swallow their food whole, passing it through a tube called the esophagus to the stomach, where digestion begins.

• Fishes and subsequent vertebrates are unable to synthesize certain amino acids, and must get them from food.

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

Excretion• Cellular wastes are filtered from fishes’ blood by the kidneys.

• A nephron is a filtering unit within the kidney that helps maintain the salt and water balance of the body and to remove cellular waste products from the blood.

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

The brain and senses• Color vision, chemical detection, hearing, and balance are

coordinated in the brain.

• The lateral line system is a sensory system the allows fish to detect movement in the water, and also helps to keep them upright and balanced.

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

Reproduction• The majority of fishes reproduce through external fertilization, but

some do have internal fertilization.

• Male and female fishes release their gametes near each other in the water in a process called spawning.

• Developing embryos get nutrition from the yolk of their eggs.

• Many fish produce large numbers of eggs and exhibit little care for their offspring.

FishesCopyright © McGraw-Hill Education

Characteristics of Fishes

Movement• Most fish have a streamlined shape for moving through water.

• Mucus lubricates their body

• Have a gas-filled space called a swim bladder that allows a fish to control it’s depth

• Fishes move through the water by contracting muscle groups on either side of their bodies.

FishesCopyright © McGraw-Hill Education

Review

Essential Questions• What are the features of vertebrates that make them different from

invertebrates?

• What are the characteristics that most fishes have in common?

• How are the characteristics of fishes adapted to aquatic life?

Vocabulary

• cartilage• neural crest• fin• scale

• operculum• atrium • ventricle• nephron

• lateral line system• spawning• swim bladder