Zoology_II;_the_chordates.pptx first year

First year
semester two
For better and deeper discovery of vertebrates including mammals and fish

1. Phylum Chordata the chordates

2. Most advanced phylum of animal kingdom -includes fish, amphibian, reptiles, birds and mammals; some of the largest or most massive animals – Notochord; flexible rodlike structure; extends the length of the body; in larva and/or adult Dorsal tubular nerve cord; (in invert ; nerve cord is ventral & paired) Pharyngeal (gill) slits; first evolved as a filter feeding apparatus endostyle or thyroid gland; specific kind of tissue found only in chordates Post-anal tail

3. Phylum Chordata chordates Primary characters include: Notochord

4. pharyngeal gill slits dorsal nerve cord ventral heart post anal tail Phylum Chordata Primary Characters

5. tailed larvae or direct development dorsal and ventral blood vessels; closed circulatory system endoskeleton Phylum Chordata Secondary Characters

6. Phylum Chordata Includes two groups: Protochordata or Acraniata – those without a cranium Craniata – those with a cranium

7. Phylum Chordata Group Protochordata (=Acraniata) (the first chordates) Includes two subphyla: Urochordata – tunicates or sea squirts Cephalochordata- lancelets

8. Subphylum Urochordata (tunicates or sea squirts) about 2000 species all marine, free-living or sessile, solitary or colonial adult has no coelom; no segmentation, no bones have a test or tunic; made of cellulose

9. dorsal atrium, chamber used for filter feeding there is a heart, with colorless blood respiration is probably function of pharynx Subphylum Urochordata (tunicates or sea squirts)

10. notochord is restricted to tail, and is found only in larvae (except for one class- there are 3 classes) larvae are called "tadpole larvae“ Subphylum Urochordata (tunicates or sea squirts)

11. most species are hermaphroditic, fertilization is external some species reproduce asexually through budding Subphylum Urochordata (tunicates or sea squirts)

12. The name tunicate derives from the cellulose-like carbohydrate material, called the tunic, which covers the outer body of tunicates. Although adult tunicates are classified as chordates, they do not have a notochord, a dorsal hollow nerve cord, or a post-anal tail, although they do have pharyngeal slits. The larval form, however, possesses all four structures. Most tunicates are hermaphrodites.

13. Cephalochordata Members of  Cephalochordata  possess a notochord, dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail in the adult stage. The notochord extends into the head, which gives the subphylum its name.

14. The lancelet, like all cephalochordates, has a head. Adult lancelets retain the four key features of chordates: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

15. about 23 species all marine, free-living or sessile, solitary or colonial, live on bottom no well developed head Subphylum Cephalochordata (lancelets)

16. many gill slits in pharyngeal basket, act in excretion and respiration have a tail; projects behind anus muscles arranged in blocks- myotomes have a notochord made of muscle fibers Subphylum Cephalochordata (lancelets)

17. are microscopic suspension feeders has closed circulatory system, with colorless blood sexes are separate; fertilization is external Subphylum Cephalochordata (lancelets)

18. Phylum Chordata Group Craniata (the vertebrates) Includes one subphylum: Subphylum Vertebrata

19. Phylum Chordata Subphylum Vertebrata Contains a wide variety of animals that include: Class Myxini – hagfishes Class Cephalaspidomorphi – lampreys Class Chondrichthyes – sharks and rays Class Osteichthyes- bony fishes Class Amphibia – amphibians Class Reptilia – reptiles Class Aves – birds Class Mammalia - mammals

20. Vertebrates are a subphylum of the phylum Chordata . Like all chordates, vertebrates have a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.  What other characteristics do vertebrates have ? What traits set them apart from invertebrate chordates? Subphylum Vertebrata

21. Characteristics of Vertebrates ( a ) The main distinguishing feature of vertebrates is their vertebral column, or backbone. The backbone runs from the head to the tail along the dorsal (top) side of the body. The vertebral column is the core of the endoskeleton. It allows a vertebrate to hold its shape. It also houses and protects the spinal (nerve) cord that passes through it. The vertebral column is made up of repeating units called  vertebrae  (singular, vertebra).

22. Vertebrate Endoskeleton ( b ) Another distinguishing feature of vertebrates is an endoskeleton made of bone or cartilage.  Cartilage  is a tough tissue that contains a protein called collagen .   Bone  is a hard tissue that consists of a collagen matrix, or framework, filled in with minerals such as calcium. 

23. the vertebrate endoskeleton includes a  cranium,  or skull, to enclose and protect the brain . It also generally includes two pairs of limbs. Limb girdles (such as the human hips and shoulders) connect the limbs to the rest of the endoskeleton.

24. Other Vertebrate Traits ( c ) Vertebrates have a system of muscles attached to the endoskeleton to enable movement. ( d ) Vertebrates have a closed circulatory system with a heart. ( e ) Most vertebrates have skin covered with scales, feathers, fur, or hair. These features serve a variety of functions. ( f ) Vertebrates have an excretory system that includes a pair of kidneys. 

25. Other Vertebrate Traits ( g ) Vertebrates have an endocrine system of glands that secrete hormones. ( h ) Vertebrates have an adaptive immune system. ( j ) Vertebrates have a centralized nervous system ; w h i c h consists of a brain in the head region. It also includes a long spinal cord that runs from the brain to the tail end of the backbone. Long nerve fibers extend from the spinal cord to muscles and organs throughout the body.

26. Vertebrate Reproduction ( k ) Vertebrates reproduce sexually, and almost all of them have separate male and female sexes . N B : Generally, aquatic species have external fertilization, whereas terrestrial species have internal fertilization. 

27. Vertebrates have one of the following three reproductive strategies: ovipary , ovovivipary , or vivipary . Ovipary  refers to the development of an embryo within an egg outside the mother’s body. This occurs in most amphibians and reptiles and in all birds.

28. Ovovivipary  refers to the development of an embryo inside an egg within the mother’s body until it hatches. The mother provides no nourishment to the developing embryo inside the egg. This occurs in some species of fish and reptiles.

29. Vivipary  refers to the development and nourishment of an embryo within the mother’s body. Birth may be followed by a period of parental care of the offspring. This reproductive strategy occurs in almost all mammals.

30. Classification 1.Hagfish: They have a cranium but no backbone; they do not have jaws; their endoskeleton is made of cartilage; they are ectothermic . 2. Lampreys: They have a partial backbone; they do not have jaws; their endoskeleton is made of cartilage; they are ectothermic .

31. 3. Cartilaginous Fish: They have a complete backbone; they have jaws; their endoskeleton is made of cartilage; they are ectothermic . 4. Ray-Finned Fish: They have a backbone and jaws; their endoskeleton is made of bones; they have thin, bony fins; they are ectothermic .

32. 5. Lobe-Finned Fish: They have a backbone and jaws; their endoskeleton is made of bones; they have thick, fleshy fins; they are ectothermic . 6. Amphibians: They have a bony endoskeleton with a backbone and jaws; they have gills as larvae and lungs as adults; they have four limbs; they are ectothermic

33. 7. Reptiles: They have a bony endoskeleton with a backbone and jaws; they breathe only with lungs; they have four limbs; their skin is covered with scales; they have amniotic eggs; they are ectothermic . 8. Birds : They have a bony endoskeleton with a backbone but no jaws; they breathe only with lungs; they have four limbs, with the two front limbs modified as wings; their skin is covered with feathers; they have amniotic eggs; they are endothermic.

34. 9. Mammals: They have a bony endoskeleton with a backbone and jaws; they breathe only with lungs; they have four limbs; their skin is covered with hair or fur; they have amniotic eggs; they have mammary (milk-producing) glands; they are endothermic.

35. Earliest vertebrates were jawless: Agnathans Earliest of these were Ostracoderms 500 million years ago Subphylum Vertebrata

36. Earliest jawed vertebrates or Gnathastomes Earliest of these were Placoderms 400 million years ago Subphylum Vertebrata