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1. Chordate Characteristics Characteristics of Chordates A chordate is an animal that in some stage of development has: 1. Notochord- dorsal rod of specialized.

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Presentation on theme: "1. Chordate Characteristics Characteristics of Chordates A chordate is an animal that in some stage of development has: 1. Notochord- dorsal rod of specialized."— Presentation transcript:

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2 Chordate Characteristics Characteristics of Chordates A chordate is an animal that in some stage of development has: 1. Notochord- dorsal rod of specialized nerves 2. A dorsal hollow nerve cord- tube just above the notochord 3. Pharyngeal pouches- small out pockets of the anterior gut (may become gills in some animals) 4. Postanal Tail-a tail that extends beyond the anus 2

3 Characteristics Continued Notochord exists only in the embryo Notochord replaced by an endoskeleton In lower chordates (fishes amphibians) pharyngeal pouches evolved into gill slits In terrestrial vertebrates pharyngeal pouches evolved into structures in throat and ear 3

4 Classification Phylum Chordata has 3 subphyla 1. Urochordata-Tunicates 2. Cephalochordata-Lancelets 3. Vertebrata Subphylum Urochordata Hollow barrel shaped Urochordates are commonly called Tunicates and Sea Squirts 4

5 Subphylum Cephalochordata Marine organism (usually shallow water) Best represented by a blade-shaped, animal called a lancelet 5

6 Subphylum Vertebrata Brain protected by an outer skull and spinal cord protected by vertebrae Organs of vertebrates are organized into 10 systems Skeletal, muscular, integumentary, digestive, respiratory, circulatory, excretory, immune, nervous, and reproductive 6

7 Characteristics of All Vertebrates Bilateral symmetry Two pairs of jointed appendages such as limbs or fins Cephalization with complex brains and sense organs True coelom lined with mesoderm Closed circulatory system-blood in vessels and heart Chambered heart Either ectothermic (cold blooded) or endothermic (warm blooded) 7

8 Vertebrate Classes Fish Amphibians Reptiles Birds Mammals 8

9 Classes of Fish 1. Agnatha-Jawless Fish 2. Chondrichthyes-Sharks Skates and Rays 3. Osteichthyes-bony fish Fishes are the most numerous of all vertebrates and most widespread in their distribution 9

10 Adaptations of Fishes Swimbladder-adaptation for buoyancy- traps gas inside their body: gas swim bladder is used to regulate their vertical position Single Loop Blood Circulation- Blood goes to the gills, is oxygenated and sent to all parts of the body 10

11 Gills Made of gill filaments where gases enter and leave the blood (Oxygen and Carbon Dioxide) Gill slit-opening at the rear of the cheek Countercurrent flow - the water passing over the gills and the blood flow inside the gills is in the opposite directions-this increases the gills efficiency Fish can extract 85 % of the oxygen passing over the gills 11

12 Circulation of Blood in Fish Single loop circulation in fish Atrium-chamber with thin, muscular walls Ventricle-a thick walled pump with much force 12

13 Excretory Organ-Kidneys Kidneys are organs made up of thousands of nephrons Nephrons are tubelike units that regulate salt and water balance and remove metabolic wastes from the blood 13

14 Reproduction in Fish Separate sexes in most fishes Usually external fertilization Yolk sac in egg contains nutrients Large numbers of eggs are fertilized during spawning Sharks, Skates and Rays fertilization is internal-most are born live Some sharks lay eggs 14

15 Adaptations of Fishes Scales limit chemical exchanges through the skin; exchanges occur through the membranes of the gills Lateral line system consists of a row of sensory structures that run the length of the body and connected by nerves to the brain; detects vibrations 15

16 Agnatha jawless Examples:Lampreys and hagfish live in the ocean Lampreys attach to fish-parasites No lateral line system Have round mouths- no scales Have Notochord, a cartilaginous skeleton, and unpaired fins 16

17 Hagfish Bottom dwellers in cold marine waters Scavengers of dead and dying fish on ocean bottom When not feeding they remain hidden in burrows on the ocean floor 17

18 Chondrichthyes CHONDRICHTHYES-SHARKES, SKATES AND RAYS chrondros=cartilageichthyes=fish movable jaws no swim bladder cartilage strengthened by calcium carbonate or bone placoid scales Teeth-modified scales 18

19 Sharks Sharks are scavengers The sharks mouth has 6 to 20 rows of backward-pointing teeth They can detect blood from an injured animal as far as 500 miles away They swim with a side-to-side motion of their asymmetric tail fins. Gas exchange requires a continuous passage of water over a sharks gills 19

20 Osteichthyes Osteon=boneichthyes=fish Skeletons rigid, calcium bases Movable jaws Gill cover or operculum Scales Most have swim bladders Most have separate sexes-fertilization external 20

21 Types of Osteichthyes or Bony Fish 1. The Lungfish resembles a short-bodied eel- Lungfishes have gills where gas exchange normally takes place 2. During dry periods they burrow unto the mud and cover themselves in mucus to stay moist until the pond refills Their "lung" is a modified swim bladder, which also absorbs oxygen and removes wastes during this dry time The various species are found in the lakes and rivers of South America, Africa and Australia 21

22 Osteichthyes Continued 2. Lobe-finned fishes-have paddle like fins with fleshy bases. 3. Ray-finned fishes have fins that are supported by the long bones called rays- Most familiar fishes and include snake-like eels, salmon, trout, bass, herring, and lantern fish (most fish we eat) 22

23 Morphology of a Bony Fish or Osteichthyes External Anatomy 1.Distinct head, trunk, and tail regions 2.Each side of head is operculum- Hard plate that opens at rear and covers and protects gills 1. Strong muscles along dorsal backbone thrust tail from side to side 23

24 Fin Characteristics Thin fan-shaped membranes Richly supplied with blood By raising and lowering fins, regulate body temperature Supported by rays or spines 1. Rays- bony yet flexible 2. Spines- bony and rigid 24

25 Scales 1.Skin covered with scales-highly modified bone that grow from pockets of skin 2.Overlap like roof shingles, all pointing toward tail to minimize friction 3.Grow during entire life of fish 4.Scales grow quickly when food is abundant and slowly when scarce 5.Skin contains pigmented chromatophores-which create various color patterns 25

26 Circulatory System Adapted for rapid swimming and other high- performance activities Consists of: Two-chambered heart Atrium- collecting chambers Ventricle- pumping chambers Blood vessels Blood-red and white blood cells Heart pumps blood to arteries capillaries in gills blood picks up oxygen gas and releases carbon dioxide into water blood moves to body tissues, where nutrients and wastes are exchanged blood returns by veins to heart 26

27 Respiratory and Excretory Systems Work Together Gills adapted for gas exchange Each has double row of thin projections called gill filaments richly supplied with capillaries Large surface area allows rapid gas exchange Gills also excrete nitrogenous wastes from body, but task carried out primarily by kidneys Kidneys filter out dissolved chemical wastes from blood 27

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