Ch.14 Fish, Amphibians, Reptiles Life Science

Section 1 – Chordates + Vertebrates Learning Objectives List the characteristics of all chordates Identify characteristics shared by vertebrates Differentiate between ectotherms and endotherms

Section 1 – Chordates + Vertebrates A. Chordates have four characteristics present at some stage of their development:  a notochord  postanal tail  nerve cord  pharyngeal pouches

1. The internal notochord extends along the upper part of the body, supporting it. a. Also extends into the postanal tail, a muscular structure at the end of developing chordates.

b. Vertebrates develop backbones that partly or entirely replace the notochord.

2. The tubelike nerve cord develops into the brain and spinal cord as most chordates mature.

3. All developing chordates have pharyngeal pouches found in the region between the mouth and digestive tube.

Pharyngeal Pouches In fish, they have developed into internal gills where oxygen and carbon dioxide are exchanged. In humans, pharyngeal pouches are present only during embryonic development. However, one pair becomes the tubes that go from the ears to the throat.

Pharyngeal Pouches

B. Vertebrates have all chordate characteristics plus distinctive additional ones. 1. Vertebrates have an endoskeleton; part of the endoskeleton is a stack of vertebrae and cartilage forming the backbone. a. The backbone protects the spinal nerve cord. b. A skull protects the brain.

2. Vertebrates are either cold-blooded ectotherms or warm-blooded endotherms. An ectotherm has an internal body temperature that changes with the temperature of its surroundings. Fish, amphibians, and reptiles are ectotherms, also known as cold-blooded animals.

An endotherm has a nearly constant internal body temperature. Birds and mammals are endotherms, which sometimes are called warm-blooded animals.

3. Vertebrates appeared in various stages beginning with water-dwelling animals about 420 million years ago to as recently as 38 million years ago, when modern mammals appeared.

Discussion Question What is the difference between ectotherms and endotherms?

Discussion Question What is the difference between ectotherms and endotherms?  Ectotherms have an internal body temperature that changes with the temperature of the animal’s surroundings.  Endotherms have a nearly constant internal body temperature.

Section 2 – Fish Learning Objectives List the characteristics of the three classes of fish. Explain how fish obtain food and oxygen and reproduce. Describe the importance and origin of fish.

Section 2 – Fish A. Fish are ectotherms with a streamlined shape, a muscular tail, fins attached to the endoskeleton, and scales that cover and protect the body.

1. Fish have well-developed sensory systems and a two-chambered heart. 2. Fish exchange carbon dioxide and oxygen through their gills.

Add to Notes  The lateral line enables a fish to sense its environment and to detect movement.

3. Fish use a variety of adaptations for obtaining food including teeth, beaks, electric shocks, and filter feeding. Some of the largest sharks are filter feeders that take in small animals as they swim. Whale Shark video https://www.youtube.com/watch?v=YtxSUnK5Uvs

The archerfish shoots down insects by spitting drops of water at them. Most fish do not chew their food. They use their teeth to capture their prey or to tear off chucks of food. Archerfish video (2 min) https://www.youtube.com/watch?v=BcLLB5vijfk

4. Fish reproduce sexually; some species use external fertilization while others use internal fertilization. Add to notes  Spawning (external fertilization) – when female fish lays large number of eggs in water and males swim over eggs and release sperm Salmon spawning https://www.youtube.com/watch?v=5HMp-GXjHtg

B. Jawless fish have: round, toothed mouths long tubelike bodies covered with scaleless, slimy skin and endoskeletons of cartilage.

C. Sharks, skates, and rays are cartilaginous fish with: skeletons of cartilage moveable jaws with well-developed teeth and tiny scales that make their skin feel like fine sandpaper. https://www.youtube.com/watch?v=1x9W70LJKVw (Finding Nemo – Bruce Video)

D. About 95% of all fish species are bony fish with skeletons of bone. 1. Most bony fish have a swim bladder that inflates and deflates, allowing the fish to rise or sink in the water.

2. Lobe-finned fish have fins that are lobelike and fleshy.

3. Lungfish have one lung and gills, allowing them to live in shallow water with little oxygen. https://www.youtube.com/watch?v=D1UKHimLZao

4. Ray-finned fish have fins made of long, thin bones covered with skin; their body plans show much variety.

E. Fish provide food for many animals and they keep insect populations in balance fish evolved from soft-bodied, filter-feeding organisms.

Discussion Question What are the 3 classes of fish?

Discussion Question What are the 3 classes of fish? 1.Jawless fish 2.Cartilaginous fish 3. Bony fish Hello…my name is Bruce!

Section 3 – Amphibians Learning Objectives Describe the adaptations amphibians have for living in water and living on land. List the kinds of amphibians and the characteristics of each. Explain how amphibians reproduce and develop.

Section 3 – Amphibians A. Amphibians are ectotherms that engage in hibernation in cold weather and estivation in hot, dry weather.

1. Some amphibians breathe through their skin; others have small, simple, saclike lungs in the chest cavity.

2. Amphibians have a three-chambered heart. 3. Amphibians need water for reproduction; eggs are fertilized externally. (Add to notes)  eggs do not have a waterproof shell and can dry out easily

4. Most amphibians go through a developmental process called metamorphosis.

(Add to notes) On each side of the head, behind the eyes, are round tympanic membranes. These membranes vibrate like an eardrum in response to sounds and are used by frogs and toads to hear.

B. Most frogs and toads use a tongue attached to the front of their mouths to capture prey such as insects, worms, and spiders.

C. Salamanders and newts hide during the day and use well-developed senses of smell and vision to hunt worms, crustaceans, and insects at night.

D. Amphibians help keep insect populations in balance, and amphibians provide food for other animals. (Not in notes) Researchers are using amphibians in regeneration studies in hopes of developing new ways of treating humans who have lost limbs or were born without limbs.

1. Amphibians are a biological indicator whose overall health reflects the health of a particular ecosystem. (They take in gases through their skin; they are sensitive to air + water pollution) 2. Amphibians are thought to have evolved from lobe- finned fish about 350 million years ago.

Discussion Question How do amphibians act as biological indicators?

Discussion Question How do amphibians act as biological indicators?  Amphibian health is a reflection of the health of an ecosystem, since amphibians live on land and water and many breathe through their skin.  They are sensitive organisms to pollutants/chemicals

Section 4 - Reptiles Learning Objectives List the relationship between the forces that objects exert on each other. Determine how reptile adaptations enable them to live on land. Explain the importance of the amniotic egg.

Section 4 - Reptiles A. Reptiles are ectotherms (cold-blooded) with a thick, dry, waterproof skin covered with scales.

1. Reptiles breathe with lungs. a. Most reptiles have a three-chambered heart. b. The three-chambered heart has a partial wall inside the main chamber.

c. Crocodilians have a four-chambered heart that completely separates oxygen-filled and carbon dioxide-filled blood. (Like humans) (Add to notes)  A four-chambered heart allows more oxygen to get to all parts of the body

2. Reptiles use internal fertilization and lay eggs with shells  the amniotic egg provides a complete environment for the embryo’s development.

Reptiles are divided into three living groups. B. Reptiles live on every continent except Antarctica and in all but polar oceans Reptiles are divided into three living groups. 3. Crocodilians 1. Lizards + Snakes 2. Turtles

1. Lizards and snakes have jaws that unhinge so they can swallow their prey whole.

Snakes “hear” vibrations in the ground that are picked up by the lower jawbone and conducted to the bones of the snake’s inner ear. Snakes wrap around and constrict their prey or inject their prey with venom

2. Turtles have a two-part shell made of hard, bony plates that protects against predators. The vertebrae and ribs are fused to the inside of the top part of the shell.

Like most reptiles, turtles provide little or no care for their young. Turtles dig out a nest, deposit their eggs, cover the nest, and leave.

Turtles live in water and on land. Tortoises just live on land

3. Crocodilians are lizard-shaped with large, deep scales on their backs. a. Crocodiles have a narrow head with a triangular-shaped snout… while alligators have a broad head with a rounded snout.

Gavials have a slender snout with a large bump on the end. b. Crocodilians are among the few reptiles that care for their young.

C. Reptiles are important predators that keep pests under control (mammals and insects)

Reptiles first appeared in the fossil record about 345 million years ago. Dinosaurs are descendants of early reptiles.

Discussion Question How do reptile eggs differ from amphibian eggs?

Discussion Question How do reptile eggs differ from amphibian eggs?  Reptile eggs are amniotic eggs which provide a complete environment for the reptile embryo’s development  Reptile eggs also have a tough, protective shell so they do not have to be laid in water.