Biology 1620 Chap. 34 Vertebrates

Four features of chordates: 1) Dorsal, Hollow Nerve Cord (differentiates into brain and spinal cord) 2) Notochord (becomes the Vertebral Column) 3) Pharyngeal Gill Slits or Pharyngeal Pouches (used for gas exchange in non-tetrapods; become parts of ear and other head and neck structures in tetrapods) 4) postanal tail

1. Name the four features of all chordates.

• Long Gestation period and relatively few Offspring has lead to population decline as sharks have been captured in greater numbers (Asians and others like shark fin soup)

10. The shark population is on the decline. What does this have to do with their mode of reproduction?

◊ Swim Bladder = Outpocketing of Pharynx; can be filled with gas or drained of gas to control buoyancy in water ◊ Gill Cover = Operculum; flexing Operculum pumps water over gills; works like a bellows; fish can remain stationary

11. What is the function of the Swim Badder and the Gill Cover in the Bony Fish?

◊ Two groups of bony fish: 1) Ray Finned - parallel bony rays support fin; no muscles within fin 2) Lobe-Finned - fins are fleshy and muscular; supported by bone with articulated joints; muscles within fins can move fins independently of one another (no ray-finned fish can do this)

12. How do ray-finned fish differ from lobe-finned fish?

A) Order Anura ("without a tail") = Frogs and Toads B) Order Urodela (Caudata) ("visible tail") = Newts and Salamanders C) Order Apoda ("without legs") = Caecilians

13. What organisms are found in the following orders of amphibians? Order Anura, Order Urodela (also known as Caudata), Order Apoda

* Frogs and Toads belong in Oder Anura, Meaning they are without a tail * Salamanders and Newt belong to order Caudata which means "visible tail" *Ceacilians Are the only ones in Oder Apoda

14. Distinguish among the characteristics of the frogs and toads, the salamanders and newts, and the caecilians.

Five distinguishing features of amphibians 1) Legs: frogs and salamanders have four legs; caecilians have lost their legs 2) Lungs 3) Cutaneous respiration: a lot of surface area of moist skin allows for diffusion of oxygen through skin which must be kept moist; supplements use of lungs 4) Pulmonary veins: return aerated blood to heart for repumping 5) Partially divided heart: imperfect separation of pulmonary and systemic blood circulation; only one ventricle in heart where oxygenated and deoxygenated blood mix

15. What are the five distinguishing characteristics of amphibians?

• both return to water to reproduce • frogs - moist skin, broad body, long hind legs -- live in or near water -- tadpole → adult frog

16. What are an amphibian's challenges to terrestrial life?

First amphibians are thought to have shown up in Greenland

17. Where (what country) were the first amphibians thought to have originated?

• broad ribs overlapped to make solid rib cage for lungs and heart; most likely could not expand and contract for breathing, so floor of mouth was lowered to push air down into windpipe

18. If the rib cage could not expand and contract, how would an organism get air to enter the lungs?

REPTILES Reptiles improved upon the innovations of amphibians in the following ways: 1) leg arrangement supports body better allowing animal to be bigger and to run 2) more efficient heart and lungs 3) skin covered with scales to decrease water loss 4) watertight covering evolved for eggs

19. In what ways did reptiles improve upon the innovations of amphibians?

-- Urochordata = tunicates and salps -- Cephalochordata = lancelets

2 .Two of the three subphyla of chordates are nonvertebrate. Name them.

1) Amniotic eggs = watertight eggs that contain a food source (yolk) and a series of four membranes. (All modern reptiles, birds, and mammals show this pattern of membranes in the eggs.) A) Chorion = outermost membrane lies just beneath the porous shell; allows exchange of respiratory gases, but retains water B) Amnion = encases developing embryo within fluid-filled cavity C) Yolk Sac = provides food from yolk via blood vessels connecting to embryo's gut D) Allantois = surrounds cavity into which waste products from embryo are excreted

20. Describe the structure of the amniotic egg. What are the functions of the four membranes of the egg?

Dry Skin A) layer of scales covers bodies; prevents water loss B) scales contain keratin - the same protein that forms claws, fingernails, hair, and bird feathers

21. Describe the skin of reptiles.

Thoracic breathing A) reptiles developed pulmonary breathing; rib cage expands and contracts to suck air into lungs and then force it out B) capacity of this system is limited by the volume of the lungs

22. Describe thoracic breathing in the reptiles.

Synapsids gave rise to Therapsids that became the mammalian line.

23. Synapsids gave rise to what line of organisms? Diapsids gave rise to what lines of organisms?

a) internal fertilization b) mixing of oxygenated and deoxygenated blood is lessened by extending septum partially through ventricle c) Crocodiles, Birds, and Mammals have a four-chambered heart d) Ectothermic = obtain their heat from external sources "Cold Blooded" (endothermic animals generate their heat internally)

24. What are the important characteristics of modern reptiles?

Order Chelonia: turtles and tortoises Order Rhynchocephalia: tuataras • only found on small islands off coast of New Zealand • have "third eye" Order Squamata: lizards and snakes • lack of limbs, movable eyelids, and external ears in snakes Order Crocodylia: Crocodiles and Alligators

25. Give examples of and list characteristics of organisms found in the following reptilian orders: Chelonia, Rhynchocephalia, Squamata, Crocodylia

Feathers = modified reptilian scales; made of keratin • Two functions of feathers are: a) provide lift for flight b) conserving heat

26. What are the functions of feathers in birds?

Flight Skeleton • bones are thin and hollow • many bones are fused and makes bird skeleton more rigid than reptilian skeleton • no other living vertebrates have fused collarbone or keeled breastbone

27. Describe the flight skeleton of modern birds.

• Archaeopteryx = fossil of first known bird

28. What is Archaeopteryx?

Birds exhibit three evolutionary novelties 1) feathers 2) hollow bones 3) superefficient lungs that permit sustained, powered flight

29. What are the three evolutionary novelties of birds?

◊ Sub-phylum Urochordata • Tunicate and salps are marine animals. • immobile as adults • only larvae have notochord and nerve cord • adults have cilia lined pharynx that brings in water where small food particles are then trapped in a sheet of mucus (mucus secreted from endostyle) • adult tunicates may be colonial • tadpole-like larvae do not feed and are free-swimming for only a few days before attaching to substrate by means of a sucker • TUNIC (tough sac of mostly cellulose) surrounds and supports animal • one group of tunicates (Larvacea) retain their tail and notochord into adulthood; possibly, vertebrates evolved from a larval form that became able to reproduce

3. Describe the body structure of an adult tunicate with that of the larval tunicate. What chordate features are lost in the adult tunicate?

Fossil record incomplete because • feather impressions rarely fossilized • hollow, delicate bones were probably crushed and not fossilized

30. For what reasons is the fossil record of birds incomplete?

Efficient respiration Efficient circulation Endothermy

31. What are three shared characteristics of all modern birds?

1) Hair - all mammals have hair 2) Mammary glands 3) Endothermy 4) Placenta

32. Describe the distinguishing characteristics of all mammals.

Meat eaters have canine teeth Herbivores have flat, chisel-like incisors for cutting off vegetation

33. What types of specialized teeth are found in mammals?

ruminants (cows, buffalo, deer, etc) Have four-chambered stomach that acts as fermentation vat; bacteria in one of stomach chambers break down the cellulose

34. How do ruminants digest plant material? How do mammals such as rodents, rabbits, horses, and elephants digest cellulose?

Development of hooves and horns • keratin, the same protein that composes hair, is the structural building material of claws, fingernails, and hooves

35. What are the differences among hooves, horns, and antlers?

Flying mammals: Bats • batwings are modified forelimbs • leathery membrane of skin and muscle stretched over four fingers

36. Bats are the only flying mammals. What is the structure of their wings?

1) Monotremes = egg-laying mammals 2) Marsupials = pouched mammals • different pattern of embryonic development

37. Describe the characteristics of the following three mammal groups: a) monotremes b) marsupials

• Lancelets look like a two-edged surgical knife. • Former genus is Amphioxus, but now known as genus Branchiostoma • Notochord retained throughout life • spend most time partly buried in sand with anterior end exposed • can swim, but don't very often • more pharyngeal gill slits than fishes • filter-feeders

4. Describe the lifestyle of a lancelet.

◊ Vertebrates differ from tunicates and lancelets in two important respects: 1) vertebral column 2) distinct and well-differentiated head (craniates)

5. Vertebrates differ from tunicates and lancelets in what two important respects? What are some other important differences?

1) Vertebral Column = bony or cartilaginous spine surrounding dorsal nerve cord (exceptions are jawless hagfish and lampreys) 2) Jaws and Paired Appendages (exceptions are lampreys and hagfish) 3) Internal Gills for extracting dissolved oxygen from water 4) Single-loop blood circulation: pathway is from Heart → Gills → Body Tissues →Back to Heart; Heart is 2-chambered 5) nutritional deficiencies - fishes must obtain the amino acids phenylalanine,

6. List and describe the five key characteristics of fishes.

The First Fishes • jawless; only had mouth positioned anteriorly that could open to take in food (modern day examples are hagfish and lampreys)

7. How did the first fishes differ from more modern fish?

Evolution of Teeth • sharks among first to develop teeth • teeth evolved from rough scales on skin • not set in jawbone, but sit on top of it • sharks may have 20 rows of teeth and when a tooth is lost, the tooth behind it moves forward to replace it

8. How did teeth evolve in fish?

Lateral Line System • series of sensory organs projecting into a canal that runs the length of fishes body • open to exterior through series of sunken pits • fish's equivalent of hearing

9. What is the lateral line system and what is its function?