Introduction to Vertebrates

1. Introduction to Vertebrates

2. Vertebrate Vocabulary Chapters 32 -35 • Chordate • vertebrate • vertebra (712) • agnathan (714) • ectothermic (724) • endothermic (724) • primate (731) • fish list the major characteristics of these animals • amphibian list the major characteristics of these animals • reptile list the major characteristics of these animals • bird list the major characteristics of these animals • Mammal list the major characteristics of these animals • amniotic egg (775) • mammary gland (806) • placenta (810) • gestation period (810) • ungulate (814)

3. vertebrates • Fishes • 3 types: jawless • cartilaginous bony Amphibians: Reptiles: Birds: Mammals:

4. Vertebrates are chordates with a backbone. They take their name from the individual segments, called vertebrae, that make up the backbone.

5. The backbone provides support for and protects a dorsal nerve cord. • It also provides a site for muscle attachment.

7. Vertebrates share a number of other characteristics, • including segmentation, • bilateral symmetry, • and two pairs of jointed appendages, such as limbs or fins.

8. Cells make up tissues. The tissues of vertebrates compose organs. • In turn, the organs compose organ systems

9. Vertebrate organ systems tend to be more complex than the organ systems found in invertebrates.

12. The first vertebrates

13. The first vertebrates were • fishes • Unlike most of the fishes you are familiar with, the earliest fishes, called agnathans, had neither jaws nor paired fins.

14. Today’s fishes belong to one of three major groups: the jawless fish: agnathans, the cartilaginous fishes: Chondrichthyes, and the bony fishes: osteichthyes.

15. Jawless fishes • - They are cylindrical, up to a meter long, with smooth, scaleless skin and no jaws or paired fins. • There are two families of jawless fishes, e.g., the hagfishes are scavengers, feeding mainly on dead fishes, while some lampreys are parasitic.

17. About 400 million years ago, sharks and bony fishes appeared. Cartilaginous fishes - They are the sharks, the rays, and the skates, which have skeletons of cartilage instead of bone. • Most sharks and bony fishes have streamlined bodies that are well adapted for rapid movement through the water.

18. Bony fishes • Bony fishes have a skeleton made of bone, which is heavier and less flexible than cartilage. Bony fishes have a swim bladder, which compensates for this weight.

19. Examples

21. Fish traits • 1. Gills. Fishes normally obtain oxygen from the oxygen gas dissolved in the water around them. They do this by pumping a great deal of water through their mouths and over their gills.

23. 2. Single-loop blood circulation • . Blood is pumped from the heart to the capillaries in the gills. From the gills, blood passes to the rest of the body and then returns to the heart. (Lungfishes, which have a double-loop circulation, are an exception.)

24. 3. Vertebral column (backbone). • All fishes have an internal skeleton made of either cartilage or bone, with a vertebral column surrounding the spinal cord. The brain is fully encased within a protective covering called the skull or cranium

25. Circulatory • - The heart of a fish is a simple pump, and the blood flows through the chambers, including a non-divided atrium and ventricle, to the gills only. Oxygenated blood leaves the gills and goes to the body proper.

27. Digestive • - The mouths shape is a good clue to what fish eat. The larger it is the bigger the prey it can consume. Fish have a sense of taste and may sample items before swallowing if they are not obvious prey items. The stomach and intestines break down (digest) food and absorb nutrients. Fish such as bass that are piscivorous (eat other fish) have fairly short intestines because such food is easy to chemically break down and digest. Fish such as tilapia that are herbivorous (eat plants) require longer intestines because plant matter is usually tough and fibrous and more difficult to break down into usable components.

28. The function of the pyloric caeca is not entirely understood, but it is known to secrete enzymes that aid in digestion, may function to absorb digested food, or do both. The liver has a number of functions. It assists in digestion by secreting enzymes that break down fats, and also serves as a storage area for fats and carbohydrates. The liver is also important in the destruction of old blood cells and in maintaining proper blood chemistry, as well as playing a role in nitrogen (waste) excretion.

29. Endocrine • - All vertebrate animals (fish, amphibians, reptiles, birds and mammals, including humans) have the same endocrine glands and release similar hormones to control development, growth, reproduction and other responses. However, the pineal gland of fish and amphibians is located near the skin and functions to detect light. This is often referred to as the third eye.

30. Excretory • - The kidney filters liquid waste materials from the blood; these wastes are then passed out of the body. The kidney is also extremely important in regulating water and salt concentrations within the fish’s body, allowing certain fish species to exist in freshwater or saltwater, and in some cases both.

31. The vent is the external opening to digestive urinary and reproductive tracts. In most fish it is immediately in front of the anal fin. Ammonia is formed immediately after the amino group is removed from protein. This process requires very little energy. Ammonia is highly soluble in water but very toxic. Aquatic animals such as bony fishes, aquatic invertebrates, and amphibians excrete ammonia because it is easily eliminated in the water.

32. Immune • - The fish immune system comprises of the non-specific and specific immune defenses, having both humoral and cellular mechanisms to resist against infectious diseases. Studies in various species of fish have shown that the spleen and head kidney are major locations of immunological activity. The relative importance of these two organs varies among different species. Previous studies have demonstrated that the head kidney is a major source of lymphocytes (including B cells) in Bluegill.

33. Germs and bugs constantly probe and try to breach the fish’s immune system to gain a strong foothold. In general, for them to be successful there has to be an underlying predisposing factor such as poor environmental conditions, poor nutrition, overcrowding or poor water quality. In addition to causing stress, which will depress the fish’s immune system, such conditions will often encourage increased numbers of opportunistic pathogens.

34. Musculo-skeletal • - Fish are covered by scales, which protect the body but do not prevent water loss. The spine is the primary structural framework upon which the fish’s body is built. It connects to the skull at the front of the fish and to the tail at the rear. The spine is made up of numerous vertebrae, which are hollow and house and protect the delicate spinal cord.

35. Nervous and Sensory • - Fish see through their eyes and can detect color. Paired nostrils, or nares, in fish are used to detect odors in water and can be quite sensitive. The lateral line is a sensory organ consisting of fluid filled sacs with hair-like sensory apparatus that are open to the water through a series of pores (creating a line along the side of the fish). The lateral line primarily senses water currents and pressure, and movement in the water.

36. Reproductive • - General speaking, reproduction in the fishes requires external water; sperm and eggs usually are shed into the water, where fertilization occurs. The zygote develops into a swimming larva that can fend for itself until it develops into the adult form.

37. Respiratory • - Fishes breathe by means of gills, respiratory organs that are kept continuously moist by the passage of water through the mouth and out the gill slits. As the water passes over the gills, oxygen is absorbed by blood and carbon dioxide is given off.

39. Evolution of Amphibians“double life” The first group of vertebrates to live on land were the amphibians, which appeared about 370 million years ago.

41. Adaptations for Life on Land • A number of major adaptations allowed some species to successfully invade land. 1. Legs. Legs support the body’s weight as well as allow movement from place to place.

42. 2. Lungs. On land, lungs carry out gas exchange. 3. Heart. Land animals tend to have higher metabolic rates than aquatic animals. The structure of the vertebrate heart allows oxygen to be delivered to the body efficiently.

44. Frogs and toads make up the largest, and probably the most familiar, group of modern amphibians.

45. Fluid loss is a problem for all terrestrial animals, that is, animals that live on land. The adaptations that permitted amphibians to live on land further developed in reptiles. • Two very important adaptations for terrestrial life evolved in reptiles. • Reptiles were the first animals to have skin and eggs that are both almost watertight, and they differ from amphibians in this respect.

48. Circulatory • - With the development of lungs, there is a change in the circulatory system. The amphibian heart has a divided atrium but a single ventricle.

49. The right atrium receives impure blood with little oxygen from the body proper, and the left atrium receives purified blood from the lungs that has just been oxygenated, but these two types of blood are mixed partially in the single ventricle. Mixed blood is then sent, in part, to the skin, where further oxygenation can occur. The frog heart is the only organ contained within the coelom, which has its own protective covering. This is the pericardium.