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KINGDOM ANIMALIA Phylum Chordata

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Presentation on theme: "KINGDOM ANIMALIA Phylum Chordata"— Presentation transcript:

1 KINGDOM ANIMALIA Phylum Chordata

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3 Chordate Relatives Common ancestry revealed by dorsal nerve tube and pharyngeal gill slits Gill slits form (throat pocketings) at sometime during development; used for feeding or gas exchange

4 Phylum Hemichordata 85 species of acorn or tongue worms
Ciliated mucus-covered proboscis, resembles acorn or tongue Burrow in sediment and feed on sediment or filter feed Elongated trunk with pharyngeal openings Single dorsal nerve cord

5 Phylum Chordata Three subphyla unified by having a notochord at some point in life cycle and metameric tail Notochord = densely packed muscle fibrils enclosed by sheath in rod shape; provides skeletal support Metameric tail = repetition of similar segments; extends beyond anus

6 Subphylum Urochordata
3000 species of tunicates or sea squirts Earliest derivative of chordate line Adults bear no resemblance to other chordates, but larval features indicate nerve cord and notochord These disappear during metamorphosis Only chordate feature remaining = gill slits (filter feed)

7 Subphylum Urochordata
Soft-bodied marine filter feeders Wide variety of sizes, shapes, and colonial structure All have outer covering (tunic) containing tunicin (cellulose-like) and in/ex-current siphons

8 Subphylum Cephalochordata
Small group of 23 species of lancelets or amphioxus Fish-like and free swimming, also burrow in sand with only head protruding Unique feeding apparatus for suspension feeding (buccal cirri/gill slits) Resemble vertebrates more; may represent living descendants of vertebrates

9 Subphylum Cephalochordata
Persistent notochord = provides structural support essential to locomotion Myotomes = segmentally arranged muscles; antagonistic and sequential contraction provide forward thrust Neural tube differentiation into an inner and outer cell layers (gray and white matter) Closed circulatory system, but lacks heart Tail fins Head

10 Subphylum Vertebrata Around 49,000 species of vertebrates
Significant not in size or age of group, but its morphological diversity, structural complexity, and trophic dominance Three novelties bind all vertebrates

11 Subphylum Vertebrata Neural crest tissue = specialized kind of ectoderm that gives rise to nervous system, retina, gill cartilage, and pigment cells Enlargement of anterior end of neural tube to form the brain Endoskeleton = backbone composed of vertebrae (bony/cartilaginous segments replace notochord during development), cranium (bony/cartilaginous housing for brain), paired pectoral and pelvic appendages

12 Subphylum Vertebrata All are bilaterally symmetrical with regional differentiation Head region = houses sensory organs, brain, anterior opening to digestive tract Trunk region = body cavities that house viscera Tail or caudal region = lacks viscera, but has muscles and skeleton (function in locomotion, reduced, or specialized)

13 Subphylum Vertebrata Metamerism (serial repetition of body parts) limited to trunk muscles, skeleton (vertebrae and ribs), and the nerves associated with trunk All have gills at some point in life cycle (breathing organs or transient developmental structures Closed circulatory system = arteries move blood to periphery from multi-chambered heart, veins move blood from periphery to heart, capillaries Myomeres associated with endoskeleton

14 Vertebrate Classes

15 Vertebrate Diversity 1. Musculoskeletal system 2. Nervous system
Major evolutionary innovations among vertebrate groups fall into four categories: 1. Musculoskeletal system 2. Nervous system 3. Respiratory/circulation systems 4. Nature of the egg

16 Musculoskeletal system
Most primitive in jawless vertebrates (hagfish, lampreys), have reduced braincase and cartilaginous gill-arch supports Hagfish = only notochord Lamprey = notochord strengthened by addition of small arches of cartilage in anterior trunk segments and small blocks of cartilage posteriorly--These are evolutionary precursors to vertebrae!

17 Musculoskeletal system
All other vertebrates: replacement of notochord with bony* vertebrae--articulate, protective housing for nerve cord development of pectoral/pelvic appendages (from fins to limbs) appearance of jaws associated with braincase *cartilage in sharks/rays-descended from bony ancestors

18 Nervous System Increased structural complexity allowed an elaborate nervous system to evolve Cephalization: elaboration of the anterior end of spinal cord to form hollow brain and sensory organs (protected by skull) Peripheral nervous system: paired nerves in every body segment (relay brain’s messages to periphery)

19 Nervous System Autonomic nervous system: function automatically without voluntary control by brain Sympathetic: increases activity, slow digestion Parasympathetic: decreases activity, stimulate digestion This complementary system best developed in mammals so they can maintain metabolic activity while still able to respond to external conditions

20 Respiratory/Circulation
Respiration: Vertebrates require more oxygen than inverts, birds/mammals = highest demands (endothermic) Soft skin, moist environment (eel, amphibian) = gas exchange across skin in addition to respiratory organ Gills or lungs = derived from the pharynx Water pumped across gills, get gas exchange Air breathed into lung, gas exchange across epithelial lining Birds also have air sacs extending from lungs into many parts of body Mammals have diaphragm to forcefully pull air in/expel air out

21 Respiratory/Circulation
Allied with respiratory system: transports oxygen, nutrients, and water to cells and removes wastes/carbon dioxide All systems closed: heart, arteries, veins, capillaries In gilled, 2-chamber heart: one atrium, one ventricle, blood enters heart via veins, leaves via aortic arches in gills (gas exchange), blood proceeds to rest of body In amphibians, aortic arches are reduced and modified into vessels in order to pass blood from lungs to 3-chambered heart (atrium separated by septum, one ventricle)

22 Respiratory/Circulation
In snakes and lizards, ventricle also has septum (incomplete 4-chambers) In birds and mammals, complete separation of oxygenated/deoxygenated blood, 4-chambered heart, efficient system with no mixing gives greater blood volume and higher blood pressure (needed for metabolic requirements) Kidneys = separate food/water from excess salt/waste in blood

23 The Egg Eggs enclosed by plasma membrane internally and vitelline membrane externally Fish and amphibian eggs pass down oviduct where chitinous chorion or gelatinous protein-polysaccharide material added (anamniote egg = no amniotic membrane) External fertilization; moist climate to prevent desiccation

24 The Egg Evolution of amniote egg: equipped with extra membrane layers of protection (amnion, yolk sac, chorion, allantois) as well as a leathery/calcareous shell In reptiles and mammals (monotremes); fertilization internal; subject to predation Marsupials and placental mammals retain young internally (helps young develop to an advanced stage before born)

25 Class Chondrichthyes 846 species of sharks and rays
Date to over 400 mya Cartilaginous endoskeleton Jawed Well-developed pectoral/pelvic fins, powerful tail fin Skin is rough due to numerous placoid scales (constantly worn out/replaced)

26 Class Chondrichthyes Teeth = enlarged placoid scales
Teeth form in actively growing skin areas in mouth just behind upper/lower jaws; skin grows, teeth pushed over edge of jaw and increase in size Teeth worn = reabsorbed or lost In rays, teeth fuse to form bony plates

27 Class Chondrichthyes Internal fertilization facilitated via unique pelvic claspers on males Anamniote eggs encapsulated in leathery case or retained in body until birth of living young

28 Class Chondrichthyes 2 informal groups: differ in body plan and dentition 1. Sharks (359 species) powerful swimmers mid-water dwelling solitary predators 2. Rays (456 species) dorsoventrally flattened, enlarged pectoral fins--subject to waves of muscular contraction bottom-dwelling eat shelled inverts (crush)

29 Class Chondrichthyes Most marine, some taxa are estuarine or freshwater (28 species) Range in size (from 20 cm to over 12 m) Commercially important in food, cosmetic, pharmaceutical, and medical products Estimated 771,400 tons of sharks/rays harvested each year by humans (while only 30 humans-2.6 tons harvested by sharks)


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