1. The Evolution of Animal Diversity: The Vertebrates
Lesson 8
Biology On-line

2. Characteristics of Chordates
Four features are evident in chordate embryos and some of these may persist into adulthood
Dorsal, hollow nerve cord
Notochord - a long support rod in the body of the vertebrate that is NOT composed of cartilage or bone
Gill slits in pharynx
Post-anal tail
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

3. Chordate Classification
Phylum – Chordata
Invertebrate chordates
Tunicates
Lancelets
Vertebrata
These have a real back bone
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

4. Invertebrate Chordates
Chordates WITHOUT Backbones

5. Tunicates
A free-swimming tunicate larva (a) and an adult tunicate (b). In the larva, the body is stiffened by a notochord, there is a dorsal nerve cord, and the tail extends beyond the anus. The only defining chordate feature retained in the adult tunicate is the pharynx with gill slits.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

6. Tunicates
Another diagram of a free-swimming tunicate larva. In the larva, the body is stiffened by a notochord, there is a dorsal nerve cord, and the tail extends beyond the anus.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

7. Lancelets
Body plan of an adult lancelet. Note the defining chordate features: a notochord, a dorsal nerve cord, a pharynx with gill slits, and a tail that extends beyond the anus.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

8. Vertebrate Classification
There Are Seven Classes of Vertebrates That Have Living Representatives.
Agnatha - jawless fishes
Chondrichthyes - cartilaginous fishes
Osteichthyes - bony fishes
Amphibia - Amphibians (frogs, salamanders)
Reptilia - Reptiles (snakes, turtles)
Aves - birds
Mammalia - mammals
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

9. Existing Jawless Fishes

10. Phylum - Chordata Subphylum -Vertebrata
Class - Agnatha
Jawless fishes (class Agnatha). Hagfishes prey on worms and scavenge. They lack jaws but have a rasping tongue. Lampreys are specialized parasite-like predators. They latch onto prey with an oral disk and use horny, toothlike parts to grasp their victims' flesh.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

11. Existing Jawed Fishes

12. Phylum Chordata - Subphylum Vertebrata Class - Chondrichthyes
Representative cartilaginous fishes (class Chondrichthyes). Sharks prey on marine invertebrates, fishes, and mammals. Skates, rays, and chimaeras patrol the sea bottoms, searching for hard-shelled prey. Chimaeras are commonly called ratfishes.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

13. Phylum Chordata - Subphylum Vertebrata Class - Osteichthyes
The typical teleost body plan and anatomy, represented here by a perch. The swim bladder is an adjustable flotation device that allows the fish to regulate its buoyancy. In all fishes, the heart has two chambers—an atrium and a ventricle.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

14. Amphibians

15. Phylum Chordata - Subphylum Vertebrata
Class - Amphibia
Two salamanders (amphibian order Caudata). Most salamanders live in the Northern hemisphere. They are carnivorous, preying on small arthropods, worms, and mollusks.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

16. Phylum Chordata - Subphylum Vertebrata
Class - Amphibia
A frog and a toad. Both are members of the amphibian order Anura, which means "without a tail." Some are aquatic, some are terrestrial, and some live in trees. The adults are air-breathing carnivores.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

17. Reptiles

18. Phylum Chordata - Subphylum Vertebrata
Class - Reptilia
A rattlesnake and a frilled lizard, both in defensive postures. Snakes arose from short-legged, long-bodied lizards. All snakes have highly movable jaws. Some, like this rattlesnake, produce poisonous venom.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

19. Phylum Chordata - Subphylum Vertebrata
Class - Reptilia
A Galápagos tortoise and a green sea turtle. All sea turtles are in danger of extinction. The turtles are threatened by human development of beach habitat and by poaching.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

20. Phylum Chordata - Subphylum Vertebrata
Class - Reptilia
Body plan of a male crocodile. A reptile’s brain is small compared to the rest of its body mass, but it governs complex forms of behavior unknown among amphibians. The cerebral cortex, the most complex part of the forebrain, evolved first among the reptiles.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

21. Birds

22. Phylum Chordata - Subphylum Vertebrata
Class - Aves
Birds range in size from tiny hummingbirds weighing as little as 2.25 grams (0.08 ounce) to ostriches weighing about 150 kilograms (330 pounds). Ostriches cannot fly, but they are excellent sprinters.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

23. Phylum Chordata - Subphylum Vertebrata
Class - Aves
Like reptiles, birds lay amniote eggs. However, birds invest far more energy than reptiles in the care of their eggs. Just about all birds build nests and incubate their eggs. The structure of a bird's egg is shown above.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

24. Phylum Chordata - Subphylum Vertebrata
Class - Aves
An artist’s reconstruction based on a 150 million-year-old fossil of an extinct bird – Archaeopteryx. Like modern birds, it had wing feathers but like reptiles it had had wing claws, teeth, and a tail composed of vertebrae. Despite its feathers, Archaeopteryx is not considered an ancestor if modern birds.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

25. Mammals

26. Phylum Chordata - Subphylum Vertebrata
Class - Mammalia
Of all the vertebrates, only female mammals feed their young with milk, a nutritious fluid produced by the mammary glands.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

27. Phylum Chordata - Subphylum Vertebrata
Class - Mammalia
Two distinctively mammalian characteristics are fur and specialized dentition. Only mammals have hair or fur to help them conserve body heat. Mammals have a distinctive arrangement of teeth. The teeth of the upper and lower jaws match up, allowing mammals to cut and chew food instead of simply swallowing it whole, as reptiles must. There are four types of mammalian teeth:molars, premolars, canines, and incisors.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

28. Phylum Chordata - Subphylum Vertebrata Montremes - egg-laying mammals
Class - Mammalia
Montremes - egg-laying mammals
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

29. Phylum Chordata - Subphylum Vertebrata Marsupials - pouched mammals
Class – Mammalia
Marsupials - pouched mammals
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

30. Phylum Chordata - Subphylum Vertebrata Eutherians - placental mammals
Class - Mammalia
Eutherians - placental mammals
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

31. Phylogenetic tree of the Animal Kingdom
The phylogenetic tree gives animal diversity an evolutionary perspective.
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002

32. Tutorial on the Vertebrates
The End of Lesson 8
Tutorial on the Vertebrates
3/16/2002
Biology 1112 – Lesson 8
© All Rights Reserved 2002