Apply It! 1. How does the meaning of amphibian relate to the Greek word from which it comes? An animal that lives for part of its life on land and part in water is living a double life. 2. Can you think of an English word besides chordate that might come from the Greek word chordé? Sample: cord 3. In the list of key terms on the next page, find another term besides endotherm that might come from the Greek word therme. Then look up the meaning of the key term and check how its meaning relates to the meaning of endotherm. An ectotherm is an animal whose body does not produce much internal heat. An endotherm, in contrast, is an animal whose body does produce internal heat to maintain its temperature.

Section 12.1: What Is a Vertebrate? • What are the characteristics of chordates and vertebrates? • How have scientists been able to infer the relationships of major groups of vertebrates? • How do vertebrates differ in the way they control body temperature?

Ancient Jawless Fish • Look backward in time, into an ocean 530 million years ago. There you see a strange-looking creature—a jawless fish—that is about as long as your index finger.

What is a Chordate? • All chordates have 4 basic features that are present at some point during their life cycle • Hollow Nerve Cord – Nerve cord in which nerves branch out at regular intervals • Notochord – Long supporting rod that runs throughout body • Pharyngeal Pouches – Paired structures in throat • Muscular Tail – Extends beyond anus • Only 4-5% of animals are chordates • Examples = Fish, Amphibians, Reptiles, Birds

Characteristics of Chordates • This lancelet shows the characteristics of a chordate: a notochord, a nerve cord down its back, and gill slits.

Evolution of Vertebrates • The pattern of vertebrate evolution is branching.

Chordate Cladogram Section 30-1 Mammals Birds Reptiles Amphibians Fishes Nonvertebratechordates Invertebrate ancestor

End of Section12.1: What Is a Vertebrate?

Section 2: Fishes • What are the characteristics of chordates and vertebrates? • How have scientists been able to infer the relationships of major groups of vertebrates? • How do vertebrates differ in the way they control body temperature?

Fish • They breathe with gills. • They are cold blooded. • Their skin is covered with scales and bony plates. • They lay eggs and have live births. • An example of a fish is a gold fish and sharks.

Characteristics of Fishes • Most fishes obtain oxygen through gills. Water flows into the mouth of the fish and then over its gills. Oxygen moves into the blood and is delivered to the cells of the fish.

Groups of Fish • Jawless Fish – • Have mouths of soft tissue with no true teeth. • Have no bones • Only vertebrates with no vertebral column as adults • Lampreys, Hagfish

CARTILAGINOUS FISH • Chondrichthyes – • Skeleton built entirely of cartilage • Sharks, sea rays

BONY FISH • Osteichthyes – • Majority of fish fall in this order • Carp, sea horse, perch, etc.

Bony Fishes • A bony fish has jaws, scales, a pocket on each side of the head that holds the gills, and a skeleton made of hard bones.

Section 3: Amphibians • What is the life cycle of an amphibian? • How are adult amphibians adapted to living on land?

Amphibians • They breathe with lungs and gills. • They are cold blooded. • Their skin is smooth and moist. • Their birth of young is eggs. • The examples are frogs, salamanders, newt, and mud puppies.

What Is an Amphibian? • During its metamorphosis from tadpole to adult, a frog’s body changes dramatically.

Living on Land • Many adult amphibians have lungs, a heart with three chambers, and a double-loop circulatory system.

Water Land Bones Lungs Ribs Efficientmovement Breathingair Support andprotection Section 30-3 Amphibians means “Double life” as larvæ they live in adults they live on and have special adaptations such as are that allow for that allow that provide are

Groups of Amphibians • Salamanders – • Long bodies and tails • Adults are carnivorous • Usually live in moist woods Spotted Salamander

Frogs and Toads – • Lack tails • Frogs have long legs and are usually tied to water • Toads have shorter legs and not as closely tied to water Fire Bellied Toad Poison Dart Frog

Caecilians – • Legless animals that burrow in moist soil • Have fishlike scales

Section 4: Reptiles • What adaptations allow reptiles to live on land? • What are the characteristics of each of the three main groups of reptiles? • What environmental change may have caused the extinction of the dinosaurs?

Reptiles • They breath with lungs. • They are cold-blooded. • There bodies are covered with dry scales. • They lay eggs. • Black snakes, Bearded dragons, Turtles, Crocodiles, and Alligators are reptiles.

Adaptations for Life on Land • The membranes and shell of an amniotic egg protect the developing embryo.

Groups of Reptiles • Lizards and Snakes • Have legs & clawed toes (lizards) external ears, moveable eyelids • Highly evolved specialized forms (venom) Coral Snake

Crocodiles and Alligators Long, typically broad snout and squat appearance All are carnivorous Protective of young; carry hatchlings in their mouth Live in tropics and subtropics Alligators live in freshwater Crocodiles live in fresh or saltwater Nile Crocodile North American Alligator

Groups of Reptiles (con.) Turtles and Tortoises – All are shelled Turtles are aquatic; tortoises are terrestrial Tuatara – Primitive reptiles found on small, remote islands Galapagos Tortoise Sea Turtle Tuatara

The Sex Ratio of Newly Hatched Alligators • The temperature of the developing eggs of the American alligator affects the sex ratio of the young. (Sex ratio is the number of females compared with the number of males.)

29.4ºC Reading Graphs: At which temperature(s) did only females hatch? The Sex Ratio of Newly Hatched Alligators

The warmer the incubation temperature, the greater the proportion of males. Drawing Conclusions: What effect does the temperature of developing eggs have on the sex of the baby alligators? The Sex Ratio of Newly Hatched Alligators

According to the graph, out of the 50 alligators that were incubated at 31.7ºC, about 40 (or 80%) were males. So 80% of 100 eggs (80) could be expected to hatch as males. Calculating: If 100 eggs developed at 31.7ºC, about how many of the young would be male? The Sex Ratio of Newly Hatched Alligators

Extinct Reptiles–The Dinosaurs • Climate change may have caused the extinction of dinosaurs and other organisms.

Section 5: Birds • What are the main characteristics of birds?

Birds • Birds breathe with lungs. • They are warm-blooded. • They are covered with feathers. • They give birth to eggs. • Examples of birds would be a red bird, hawk, and chicken. • Some unusual birds are the ostrich, flamingo, and penguin.

Characteristics of Birds • The bodies of most birds have adaptations for flight.

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