Transcript Chapter 39 Fishes Table of Contents Section 1 Introduction to Vertebrates Section 2 Jawless and Cartilaginous Fishes Section 3 Bony Fishes.

Chapter 39
Fishes
Table of Contents
Section 1 Introduction to Vertebrates
Section 2 Jawless and Cartilaginous Fishes
Section 3 Bony Fishes
Chapter 39
Section 1 Introduction to
Vertebrates
Objectives
• Identify the distinguishing characteristics of
vertebrates.
• List an example for each of the nine classes of
vertebrates.
• Describe the characteristics of the early vertebrates.
• Explain the importance of jaws and paired fins for
fishes.
Chapter 39
Section 1 Introduction to
Vertebrates
Characteristics
Vertebrates are members of the subphylum
Vertebrata, within the phylum Chordata.
All Chordates share the following characteristics.
•
•
•
•
Notochord
Dorsal hollow nerve cord
Pharyngeal gill slits
Post-anal tail
Chapter 39
Section 1 Introduction to
Vertebrates
Characteristics, continued
Vertebrates are distinguished from chordates by:
• Vertebrae - bones or cartilage that surround the
dorsal nerve cord and form the spine.
• A cranium - a skull that protects the brain
• An endoskeleton - an internal skeleton made of
bone or cartilage
Chapter 39
Section 1 Introduction to
Vertebrates
Characteristics, continued
Vertebrates are divided into nine classes:
• Myxini - hagfishes
• Cephalaspidomorphi - lampreys
• Chondrichthyes - sharks, rays, skates, and
ratfishes
• Actinopterygii - ray-finned fishes
• Sarcopterygii - lobe-finned fishes
• Amphibia - frogs, toads, salamanders, and
caecilians
• Reptilia - lizards, snakes, and turtles
• Aves - birds
• Mammalia - mammals
Chapter 39
Evolutionary
Relationships
Among
Chordates
Section 1 Introduction to
Vertebrates
Chapter 39
Section 1 Introduction to
Vertebrates
Vertebrate Evolution
• Most biologists think that vertebrates originated
about 560 million years ago.
• The first fish were jawless.
• About 450 million years ago, the first fishes with
jaws and paired fins appeared.
• Jaws are thought to have evolved from the first
pair of gill arches, the skeletal elements that
support the pharynx.
Chapter 39
Section 1 Introduction to
Vertebrates
Evolution of Jaws
Chapter 39
Section 1 Introduction to
Vertebrates
Vertebrate Evolution, continued
The advantages to jaws and paired fins:
• Paired fins increased fishes’ stability and
maneuverability in water
• Jaws allowed fishes to seize and manipulate prey
Chapter 39
Section 1 Introduction to
Vertebrates
Origin of Jaws
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Visual Concept
Chapter 39
Section 1 Introduction to
Vertebrates
Advantage of Paired Fins
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Visual Concept
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Objectives
• Identify three characteristics that make fishes well
suited to aquatic life.
• Describe three sensory systems in fish.
• Evaluate the similarities between jawless fishes and
early vertebrates.
• Identify two characteristics of cartilaginous fishes.
• Contrast reproduction in lampreys with reproduction
in cartilaginous fishes.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Fish Adaptations
Fish have several adaptations that make them well
suited to life in water:
• Streamlined body plan - allows fish to move
rapidly in water
• Adaptations for buoyancy - stored gases or lipids
help maintain vertical position in water
• Efficient respiration - internal gills exchange
gases efficiently
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Fish Adaptations, continued
Adaptations for salt and water homeostasis • The concentration of solutes in a fish’s body
usually differs from the concentration of solutes
in the water.
• Fish have adaptations to maintain ion and water
homeostasis.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Fish Adaptations, continued
Sensory adaptations - Fish have a variety of organs that
allow them to sense their environment.
• Sight: fish eyes are similar to eyes of land vertebrates
• Sound: fish have internal ears sensitive to sound
• Chemoreception: the ability to detect chemicals in the
environment includes the senses of smell and taste.
Fish have nostrils and tastebuds. Tastebuds may be
located in their mouths, on their lips, fins, and skin,
and on whisker-like organs called barbels.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Fish Adaptations, continued
Unique senses:
• Lateral line: the lateral line is a system of canals in the
skin that allow fish to sense vibration in the water
• Ampulae of Lorenzini: cartilaginous fishes have sense
organs called ampulae of Lorenzini that can detect
weak electrical fields
• Electroreception and Magnetoreception: some fish
have the ability to detect electrical and magnetic
fields
Chapter 39
Lateral
Line in
Fishes
Section 2 Jawless and
Cartilaginous Fishes
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Lateral Line System
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Visual Concept
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Characteristics of Fish
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Visual Concept
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Jawless Fishes
Only two classes of jawless fishes are alive today:
• Hagfishes (class Myxini) Hagfishes are bottomdwellers that feed on dead and dying fish.
• Lampreys (class Cephalaspidomorphi) Lampreys
can be free-living or parasitic. Parasitic lampreys
attach themselves to their host with disc-shaped
mouths and feed on the blood and body fluids of
other fishes. All lampreys breed in fresh water.
Fertilization occurs outside the body - external
fertilization.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Cartilaginous Fishes
All cartilaginous fishes:
• belong to the class Chondrichthyes.
• have skeletons made of cartilage - a flexible
lightweight material made of cells surrounded by
tough fibers of protein.
• have skin covered with placoid scales - small,
toothlike spines that feel like sandpaper. Placoid
scales probably reduce turbulence and increase
swimming efficiency.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Cartilaginous Fishes, continued
Sharks:
• Sharks have torpedo shaped bodies that reduce
turbulence when swimming, called a fusiform body
shape.
• Some sharks are filter feeders, and have slender
projections on the inner surface of their gills, called
gill rakers, that filter the water.
• The mouth of a typical shark has 6 to 20 rows of teeth.
When a tooth breaks or wears down, a replacement
moves forward. One shark may use more than
20,000 teeth over its lifetime.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Cartilaginous Fishes, continued
Rays and Skates:
• Rays and skates have flattened bodies with
paired wing-like pectoral fins and, in some
species, whip-like tails.
• Rays have diamond- or disk-shaped bodies. Most
skates have triangular bodies.
• Rays and skates are primarily bottom dwellers,
and most feed on mollusks and crustaceans.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Cartilaginous Fishes, continued
Ratfishes:
• Ratfishes are a small group of strange looking
fish that have a flap of skin covering their gill
slits.
• Ratfishes have long, rat-like tails and feed on
crustaceans and mollusks.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Cartilaginous Fishes, continued
Adaptations in Cartilaginous Fishes:
• Some sharks push water through their mouth and
over their gills by swimming.
• Most cartilaginous fish pump water over their gills
by expanding and contracting their mouth cavity
and pharynx.
• When lying on the bottom, rays and skates draw
water in to their gills through spiracles, two large
openings on the top of the head, behind the eyes.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Cartilaginous Fishes, continued
Adaptations in Cartilaginous Fishes:
• Sharks convert ammonia to urea in their bodies.
• Sharks retain large amounts of urea in their bodies
to raise the concentration of solutes in their bodies
to the same level as that found in sea water.
• Sharks still tend to take up sodium and chloride
ions.
• The rectal gland removes excess sodium and
chloride ions from the body.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Cartilaginous Fishes, continued
Adaptations in Cartilaginous Fishes:
Cartilaginous fishes maintain their position in the
water in two ways.
1. The caudal and pectoral fins generate lift, or
upward force, as the fish swims.
2. Many cartilaginous fish store large amounts of
lipids, usually in the liver. Lipids are less dense
than water.
Chapter 39
Section 2 Jawless and
Cartilaginous Fishes
Cartilaginous Fishes, continued
Reproduction in Cartilaginous Fishes:
• Fertilization occurs inside the body of the female,
called internal fertilization.
• Some cartilaginous fish lay eggs.
• The eggs of many species develop within the
female’s body.
• In some species, the mother nourishes the
developing young while they are in her body.
Chapter 39
Section 3 Bony Fishes
Objectives
• List three characteristics of bony fishes.
• Distinguish between lobe- finned fishes and ray-finned
fishes.
• Describe three key features of bony fishes’ external
anatomy.
• Summarize the major body systems in bony fishes.
• Describe the function of the swim bladder.
• Discuss reproduction in bony fishes.
Chapter 39
Section 3 Bony Fishes
Characteristics of Bony Fishes
Bony fishes have three key features:
• Bone - the skeletons of most bony fishes contain
bone.
• Lungs or swim bladder - early bony fishes had lungs,
organs which exchange gas between the air and
blood. Most bony fishes today have a swim bladder, a
gas-filed sac that is used to control buoyancy.
• Scales - scales protect the body of a bony fish and
reduce friction when swimming.
Chapter 39
Swim Bladder
in Bony Fish
Section 3 Bony Fishes
Chapter 39
Section 3 Bony Fishes
Swim Bladder
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Visual Concept
Chapter 39
Section 3 Bony Fishes
Characteristics, continued
There are two main groups of bony fishes:
• Lobe-finned fishes - have fleshy fins supported
by a series of bone.
• Ray-finned fishes - have fins that are supported
by long, segmented, flexible bony elements called
rays.
Chapter 39
Section 3 Bony Fishes
Characteristics of Bony Fishes
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Visual Concept
Chapter 39
Section 3 Bony Fishes
External Anatomy
• Operculum Most bony fish have an operculum, a
hard plate that opens at the rear and covers and
protects the gills.
• Fins The fins of most fish are supported by rays or
spines. Rays are flexible, spines are rigid.
• Skin The skin of most bony fish are covered with
scales. Scales are thin, round disks of a bonelike
material that grow from pockets in the skin and
overlap like shingles.
Chapter 39
Section 3 Bony Fishes
External Structures of Fish—Yellow Perch
Chapter 39
Section 3 Bony Fishes
Anatomy of a Bony Fish
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Chapter 39
Section 3 Bony Fishes
Internal Anatomy, continued
Digestive system
Food passes from the mouth into the pharynx, through
the esophagus, to the stomach. From the stomach
food passes into the intestine, where nutrients are
absorbed. Undigested material is eliminated through
the anus.
Chapter 39
Section 3 Bony Fishes
Internal Structure of Fishes—Yellow Perch
Chapter 39
Section 3 Bony Fishes
Internal Anatomy, continued
Circulatory system
The circulatory system of a fish delivers oxygen and
nutrients to the cells of the body.
The circulatory system consists of a heart, blood
vessels, and blood.
The heart pumps blood through arteries to small, thinwalled vessels called capillaries, in the gills. From the
gills, the blood travels to the body tissues, where
nutrients and wastes are exchanged. The blood
returns to the heart through veins.
Chapter 39
Section 3 Bony Fishes
Internal Anatomy, continued
Circulatory system
The heart of a bony fish has two chambers in a row, as shown
below. Blood from the body enters the sinus venosus, moves
into the atrium, then into the ventricle. From the ventricle it
enters the conus arteriosus, and then goes to the gills.
Chapter 39
Section 3 Bony Fishes
Fish Heart Structure
Chapter 39
Section 3 Bony Fishes
Fish Heart and Single-Loop Circulation
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Visual Concept
Chapter 39
Section 3 Bony Fishes
Internal Anatomy, continued
Respiratory system
• Fish use gills for gas exchange.
• Water flows across the gill filaments in a direction
opposite to blood flow, called countercurrent
flow.
• Countercurrent flow allows more oxygen to
diffuse into the blood than would be possible if
blood and water flowed in the same direction.
Chapter 39
Section 3 Bony Fishes
Respiration in Fishes
Chapter 39
Section 3 Bony Fishes
Parts of Fish Gills and Countercurrent Flow
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Visual Concept
Chapter 39
Section 3 Bony Fishes
Internal Anatomy, continued
Excretory system
• The kidneys filter chemical wastes from the blood to
form urine, a solution containing ammonia, ions such as
salts, and water.
• The kidneys help regulate the ion and water balance in
fish.
• The gills also allow wastes to diffuse from the blood into
the water and help regulate ion and water balance in
fish.
Chapter 39
Section 3 Bony Fishes
Fish Kidneys
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Chapter 39
Section 3 Bony Fishes
Parts of a Nephron
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Chapter 39
Section 3 Bony Fishes
Internal Anatomy, continued
Swim bladder
• The swim bladder is a thin-walled sac in the abdominal
cavity that contains a mixture of oxygen, carbon dioxide,
and nitrogen obtained from the bloodstream.
• Swim bladders evolved from balloonlike lungs, which
ancestral bony fishes may have used to supplement the
oxygen absorbed by the gills.
• In some fish the swim bladder is known to amplify sound
by vibrating and transmitting sound to the inner ear.
Chapter 39
Section 3 Bony Fishes
Internal Anatomy, continued
Nervous system
The nervous system of a bony fish includes the brain,
spinal cord, nerves, and various sensory organs.
The fish brain consists of several parts:
• Olfactory bulb - processes information about smell
• Cerebrum - integrates information from other parts of
the brain
• Optic tectum - processes information about sight and
from the lateral line system
• Cerebellum - coordinates muscle movement and
balance
• Medulla oblongata - controls the function of some
organs and relays information from the spinal cord
Chapter 39
Section 3 Bony Fishes
Internal Anatomy, continued
Nervous system
The fish brain has a well-developed medulla to
coordinate muscle control.
Chapter 39
Section 3 Bony Fishes
Reproduction
Spawning
• Reproductive behavior in bony fishes is called
spawning.
• Fertilization in most fish takes place outside the body.
• Many species of fishes lay large numbers of eggs.
• Some species of fish carry the eggs within their bodies
until the eggs hatch.