Characteristics of Vertebrates
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Animals belonging to subphylum Vertebrata have a vertebral column and
specialized cells that develop from the nerve cord.
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Classes of vertebrates include fishes, amphibians, reptiles, birds, and
mammals.
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Fishes
Characteristics of Vertebrates
Vertebral column
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The notochord is replaced by a vertebral column that protects and surrounds
the dorsal nerve cord.
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Made of cartilage – flexible tough material found in skeletons, or bone
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The vertebral column functions as a strong, flexible rod that muscles can pull
against during swimming or running.
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Fishes
Characteristics of Vertebrates
Neural crest
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A neural crest is a group of cells that develop from the nerve cord in
vertebrates.
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Portions of the brain and skull, certain sense organs, and some nerve fibers
are some of the structures that develop from the neural crest.
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Fishes
Characteristics of Fishes
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Fishes are found in a variety of aquatic habitats including seas, lakes, ponds,
streams, and marshes.
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Most fishes have vertebral columns, jaws, paired fins, scales, gills, and
single-loop blood circulation.
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Fishes
Characteristics of Fishes
Jaws
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Anterior gill arches evolved into jaws in ancient fishes.
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The development of jaws allowed ancient fishes to prey on a larger range of
animals.
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Fishes
Characteristics of Fishes
Paired fins
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A fin is a paddle-shaped structure on a fish or other aquatic animal that is
used for balance, steering, and propulsion.
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Paired fins reduce the chance of rolling to the side and allow for better
steering during swimming.
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Fishes
Characteristics of Fishes
Scales
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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
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Fishes
Characteristics of Fishes
Gills
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Fishes get oxygen when water that enters their mouths flows across their
gills, where oxygen from the water diffuses into the blood.
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The flow of blood in the gills is opposite the flow of water across the gills,
allowing for more efficient uptake of oxygen
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Some fish protect their gills with operculum, a movable flap.
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Fishes
Characteristics of Fishes
Circulation
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Vertebrates have a closed circulatory system.
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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.
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Fishes
Blood Flow in Fish
Animation
FPO
Add link animation from page 824 (figure 8) here.
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Fishes
Characteristics of Fishes
Feeding and digestion
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Ancient fishes were most likely filter feeders and scavengers.
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Most fishes swallow their food whole, passing it through a tube called the
esophagus to the stomach, where digestion begins.
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Fishes and subsequent vertebrates are unable to synthesize certain amino
acids, and must get them from food.
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Fishes
Characteristics of Fishes
Excretion
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Cellular wastes are filtered from fishes’ blood by the kidneys.
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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.
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Fishes
Characteristics of Fishes
The brain and senses
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Color vision, chemical detection, hearing, and balance are coordinated in the
brain.
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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.
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Fishes
Characteristics of Fishes
Reproduction
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The majority of fishes reproduce through external fertilization, but some do
have internal fertilization.
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Male and female fishes release their gametes near each other in the water in
a process called spawning.
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Developing embryos get nutrition from the yolk of their eggs.
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Many fish produce large numbers of eggs and exhibit little care for their
offspring.
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Fishes
Characteristics of Fishes
Movement
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Most fish have a streamlined shape for moving through water.
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Mucus lubricates their body
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Have a gas-filled space called a swim bladder that allows a fish to control it’s
depth
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Fishes move through the water by contracting muscle groups on either side
of their bodies.
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Fishes
Review
Essential Questions
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What are the features of vertebrates that make them different from
invertebrates?
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What are the characteristics that most fishes have in common?
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How are the characteristics of fishes adapted to aquatic life?
Vocabulary
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cartilage
neural crest
fin
scale
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operculum
atrium
ventricle
nephron
• lateral line system
• spawning
• swim bladder
Fishes