1. Classification Activity

2. Fish: 2—bluefish, 3—blue shark, 8—lungfish

3. Amphibians: 5—blue-spotted salamander, 7—mudpuppy, 16—caecilian, 19—green frog

4. Reptiles: 4—ichthyosaur, 6—blue racer, a snake, 11—pterosaurs, 12—Tyrannosaurus rex, 17—leatherback turtle, 18—blue-tailed skink, a lizard

5. Birds: 9—blue penguin, 10—bluebird, 15—blue duck

6. Mammals: 1—blue whale, 13—gray bat, 14—duck-billed platypus

7. An Evolutionary Tree of the Vertebrates
Tetrapods
Chondrichthyes
(sharks, rays)
(coelacanths)
Actinistia
(ray-finned fish)
Actinopterygii
Petromyzontiformes
(lampreys)
(lungfishes)
Dipnoi
salamanders)
Amphibia
(frogs,
(turtles, snakes
crocodiles,
Reptilia
birds)
Mammalia
(mammals)
Dorsal nerve cord, notochord,
pharyngeal gill slits, post-anal tail
Vertebral column
Jaws
Lungs
Skull
Lobed fins
Limbs
Amniotic egg
Hair, milk
An Evolutionary Tree of the Vertebrates

8. Vertebrate Adaptations
Several adaptations have allowed vertebrates to successfully invade most habitats
presence of an internal skeleton that can grow and repair itself allowed for greater size and mobility, enabling these animals to invade most habitats
Jaws evolved to allow these animals to exploit a much wider range of food sources than jawless animals that preceded them
The development of paired appendages (fins, legs, wings) helped to stabilize movement
The increased size and complexity of the brain and sensory structures allowed these animals to perceive their environment in detail and to respond in a variety of ways

9. What Are the Major Groups of Vertebrates?
Today, vertebrates include the following groups:
Lampreys
Cartilaginous fishes
Ray-finned fishes
Lungfishes
Amphibians
Reptiles
Mammals

10. lampreys Some lampreys parasitize fish jawless
rounded sucker that surrounds the mouth
spinal cord is protected by cartilaginous segments
live in both fresh and salt waters

11. Cartilaginous fishes Cartilaginous fishes are marine predators
They are of the class Chondrichthyes, and include sharks, skates, and rays
Most are marine
They possess jaws and a cartilaginous skeleton
Their body is protected by a leathery skin embedded with tiny scales

12. Bony fishes the most diverse vertebrates
Bony fish are found in nearly every watery habitat, both freshwater and marine
This group includes:
Ray-finned fishes, such as the angler fish, the moray eel, and the sea horse
Lobe-finned fishes, which include the lungfish and the coelacanth

13. The Diversity of Ray-Finned Fishes
most diverse and abundant group of vertebrates
Fins which are formed by webs of skin supported by bony spines
bony skeleton
skin is covered with interlocking scales
two-chambered heart
gills are for respiration
Most have a swim bladder

14. Lobed-finned fishes
fleshy fins that contain rod-shaped bones surrounded by a thick layer of muscle
Some of these modified fleshy fins could be used to drag the fish from a drying puddle to a deeper pool
This gave rise to the first vertebrates to invade land—the amphibians
Some of the lineages of lobefins left descendents that survive today and are the tetrapods (amphibians, reptiles, and mammals)

15. Amphibians: frogs, toads, salamanders, and caecilians
Amphibians begin life adapted to an aquatic environment (e.g., tadpoles have gills) They later mature into semi-terrestrial adults with lungs
three-chambered heart
adults respire through lungs and moist skin
Most have four limbs
Most are confined to moist habitats
use of external fertilization requires water
eggs, protected only by a jelly-like coating, are vulnerable to water loss

16. Reptiles class Reptilia and are adapted for life on land
These animals evolved from an amphibian ancestor about 250 million years ago
Reptiles include lizards, snakes, alligators, crocodiles, turtles, and birds
They respire exclusively through lungs
tough scaly skin that protects the body and resists water loss
internal fertilization with shelled amniotic egg
three- or four-chambered hearts
efficient lungs and do not use their skin as a respiratory organ

17. Birds distinctive group of reptiles
They appear in the fossil record 150 million years ago
They are distinguished from other reptiles by feathers, which are highly specialized reptilian body scales
Modern birds retain scales on their legs, which is evidence of the ancestry they share with the rest of the reptiles
The earliest known bird is called Archaeopteryx

18. Archeopteryx, the Earliest-Known Bird
Fig

19. Mammals Mammals are warm-blooded with high metabolic rates
Mammals appeared in the fossil record about 250 million years ago
They did not diversify and dominate terrestrial habitats until the dinosaurs became extinct (65 million years ago)
Mammals are warm-blooded with high metabolic rates
a four-chambered heart
hair that protects and insulates
legs designed for running rather than crawling
provide milk to their offspring
sweat, scent, and sebaceous (oil-producing) glands, which are not found in other vertebrates
Mammals are subdivided into three groups
Monotremes
Marsupials
Placental mammals

20. Monotremes are egg-laying mammals
This group includes only three species, the platypus and two species of spiny anteater (echidnas), and are found only in Australia and New Guinea
Platypuses forage for food in the water and eat small vertebrate and invertebrate animals
Echidnas are terrestrial and eat insects and worms they dig out of the ground
Monotremes lay leathery eggs rather than giving birth to live young
The newly hatched young are nourished from milk secreted by the mother

21. Marsupia
Species include the opossums, koalas, kangaroos, wallabies, wombats, and the Tasmania devil
In marsupials, embryos begin development in the uterus of the female
Young are born at a very immature stage and must crawl to and grasp a nipple to complete development
Post-birth development, in most, is completed in a protective pouch

22. Placental mammals inhabit land, air, and sea
This highly diverse class includes bats, moles, impalas, whales, seals, monkeys, and cheetahs
The uterus contains a placenta that functions in gas, nutrient, and waste exchange between circulatory systems of mother and embryo
In placental mammals, young are retained in the uterus for their entire embryonic development