1. Vertebrate Survey Anatomy and Physiology of Vertebrates

2. Vertebrate Evolution
Phylum Chordata is the group of animals with a notochord – a flexible, supporting structure along the back
Contains the invertebrate chordates, and Subphylum Vertebrata, which have evolved vertebral columns
Serves as site for muscle attachment, protects nerve cord

3. Trends in Vertebrate Evolution
Development of true bony jaws
Development of paired pectoral and pelvic limb girdles
Development of bones
Most vertebrates have two sets of appendages (arms and legs), a closed circulatory system with a ventral heart, and either gills or lungs for breathing

4. Class Agnatha Jawless fish Ex. Lampreys and hagfishes
Only living vertebrates without jaws
Parasites – survive by attaching themselves to other fish or aquatic animals, feeding on their blood and body fluids
Scavengers – eat decaying carcasses

5. Class Chondrichthyes Cartilaginous fish Ex. Sharks, skates, rays
Skeletons made of cartilage
Some are fearsome predators, other eat small fish, mollusks, or plankton

6. Class Osteichthyes Bony fish
Contain half of all vertebrate species, all aquatic habitats
Ray-finned fish – sub-class containing almost all fish species – well-developed bone systems, specialized jaws with teeth
Lobe-finned fish – sub-class with lungs and gills, relatives of amphibians

7. Class Amphibia (amphibians)
Lay eggs in water and spend part of their life cycle there (gills)
As adults, live on land and breathe through lungs
Most have moist skin, as part of their respiration occurs through skin

8. Class Amphibia Examples include:
Newts and salamanders (lay eggs in water, hatch into young that resemble adults – larvae have gills that disappear and are replaced by lungs as they grow)
Frogs and toads (eggs hatch in water as tadpoles, which look completely different from adults)

9. Class Reptilia (reptiles)
Fully terrestrial
Reproduce by internal fertilization – egg/sperm fuse within body of the female
Produce leathery eggs to prevent water loss
Dry scaly skin to retain moisture
Developed lungs

10. Class Reptilia
Order Chelonia – turtles and tortoises, protective shell of bony plates (long fossil record)
Order Crocodilia – crocodiles, alligators, caimans (long fossil record)
Order Squamata – lizards and snakes, most abundant group

11. Class Aves (Birds) Only vertebrates with feathers
Used for flight and conservation of body heat
Lay eggs

12. Class Mammalia (mammals)
Named for presence of mammary glands, enable females to nourish young with milk
Have hair to retain body heat

13. Class Mammalia Three groups:
Monotremes – egg-laying mammals like duck-billed platypus – have body hair/fur, lay leathery eggs
Marsupials – live young born very early in their development and continue to develop within marsupium – kangaroos, koalas, opossums
Placental mammals – largest group, names for placenta (organ that connects mother with developing embryo, allows for nutrient, gas, and waste exchange)

14. Support and Movement
All have an endoskeleton surrounded by muscles and skin
Vertebral column (backbone) is the main part of the skeleton
Adapting to life on land led to changes in limb positions
Amphibians had limbs that are horizontal while reptile limbs are vertical to support increased body mass

15. Feeding and Digestion
All food sources presented problems as vertebrates evolved
Meat is easy to digest, but must first be caught then cut up for swallowing
Plant matter is easy to find, but must be pulverized and shredded before swallowing, and cellulose is hard to digest

16. Feeding and Digestion Adaptations are present in teeth
Meat requires teeth that hold, shred
Plants require teeth that grind/pulverize

17. Feeding and Digestion Adaptations seen in digestive tracts
Meat digests easily, so carnivores have short digestive tracts that secrete enzymes to break down proteins
Plants need to be broken down slowly, so herbivores spend more time chewing/rechewing, and long digestive tracts full on bacteria help digest cellulose

18. Respiration (gas exchange)
Method/system depends on environment
Fish rely on gills for respiration
Amphibians have gills as tadpoles and poorly developed lungs as adults
No muscles to inflate/deflate lungs
Rely on diffusion through thin, moist skin

19. Respiration (gas exchange)
Reptiles are fully adapted to life on land and have more developed lungs that are divided into chambers to increase surface area
Reptiles also have muscles to inflate/deflate lungs

20. Respiration (gas exchange)
Mammals require higher rate of gas exchange because of higher metabolic rate
Most developed lungs
Bronchi (air tubes) enter lungs then branch to create more surface area, ending in alveoli

21. Respiration (gas exchange)
Alveoli are bubblelike structures surrounded in capillaries
Efficient at gas exchange, but inefficient because air must move in and out through the same passageway

22. Respiration (gas exchange)
Birds have highest requirements for lung efficiency because they fly
Have branched bronchi and alveoli like mammals, but also have air sacs within some bones
Air is pumped in one direction

23. Internal Transport Closed circulatory systems
Two types: single-loop and double loop

24. Internal Transport
Single-loop circulatory systems are found in fish – blood is pumped from the heart to the gills where respiration takes place, then flows from the gills to the rest of the body, returning to the heart
Heart has two chambers – one atrium (receives) and one ventricle (pumps)

25. Internal Transport
Vertebrates with lungs have a double-loop circulatory system
First loop carries blood between the heart and lungs (pulmonary)
Second loop carries blood between the heart and the rest of the body (systemic)

26. Internal Transport
Amphibians and reptiles have a three-chambered heart – two atria and one ventricle
Birds and mammals have a four-chambered heart – two atria and two ventricles

27. Temperature Control
Vertebrates need to control their body temperature because chemical reactions operate differently at various temperatures
Need a way to heat the body, conserve that heat, and eliminate excess heat

28. Temperature Control
Fish, amphibians, and reptiles are ectothermic because they rely on interactions with their environment to control body temperature
Lay in sun to warm themselves, stay in shade or burrow to cool down

29. Temperature Control
Mammals and birds are endothermic because they generate heat in body tissues through chemical reactions in the body
Also have layers of fat and fur/feathers to conserve heat
Shivering generates more heat, panting or sweating dissipates heat

30. Excretion
Elimination of nitrogen-containing wastes linked to maintaining water balance
Aquatic vertebrates get rid of ammonia by diffusion (fish through gills, amphibians through skin)
They also have the beginnings of a kidney (primitive, gets more complex)

31. Excretion Mammalian kidney most complex
Use the conversion to urea and uric acid and concentration to conserve water
Urea eliminated in urine, uric acid in solid waste

32. Response All vertebrates are cephalized
Bundle of nerves and neural connections in head called the brain, and the long, thick collection of nerves running down the back is the spinal cord
Spinal cord protected by vertebral column

33. Response
Pairs of nerves run out between individual vertebrae to connect muscles, organs, and sensory receptors around the body
More complex behavior means more complex brain
All vertebrates have a cerebrum (thinking) and cerebellum (balance, coordination, movement)

34. Reproduction All vertebrates reproduce sexually
Fish and amphibians have external fertilization
Female lays thousands of eggs in water, male deposits sperm
Young develop and hatch in water

35. Reproduction
Reptiles, birds, and mammals have internal fertilization (inside female)
Fewer eggs are produced
Developing embryo is nourished inside the egg by a yolk (food) and wrapped in membranes (called the amniotic egg)
Membranes bathe embryo in liquid and receive and store wastes

36. Reproduction
Amniotic egg also has a shell for protection and allows for gas exchange
Important step in evolution – no water necessary

37. Reproduction How eggs are handled is different amongst vertebrates
Oviparous animals lay their eggs, and the embryo completes its development and hatches outside of the female’s body

38. Reproduction
Ovoviviparous animals keep their eggs inside the body until the embryo fully develops and hatches
Viviparous animals have eggs with very little yolk (if at all) because the female nourishes the embryo internally for a long period of time, and the young are born alive (do not hatch)