Untitled Flashcards Set

Vertebrate origins I. Phylum Chordata A.Subphylum Urochordata (Tunicata) 1. = tunicates & sea squirts 2. Invertebrates 3. free-swimming/sessile B.Subphylum Cephalochordata = lancelets 1. Small eel-like animals 2. Invertebrate 3. In shallow tropical ocean 4. Can swim a)Usually bury themselves in sand b)Filter feed II. Characteristics of ALL chordates A.All have notochords at some point 1. = flexible skeletal support 2. Rod-shaped B.All have hollow nerve cord 1. Runs along back 2. Formed from ectoderm C.Pharyngeal slits 1. = slits thru-body wall in pharynx, part of gut immediately behind mouth D.Post-anal tail 1. Has segments of muscle tissue used in movement E.Endoskeleton 1. = internal skeleton made of bone/cartilage 2. Bone & cartilage are connective tissue a)Made of collagen fibers b)Support & protect soft structures c) Provide attachment for muscles 3. Divided into 3 parts a)Braincase = protects brain b)Vertebrae c) Connected bone structures 4. Made of cells that are constantly breaking down & reforming bone a)Skeleton constantly changes shape & size I. Characteristics of Vertebrates - Subphylum Vertebrata A.Have vertebral column w/ spinal cord 1. Includes fish, amphibians, reptiles, birds, & mammals 2. Notochord replaced w/ vertebral column a)Surrounds & protects spinal cord 3. Made of bone & cartilage a)Cartilage = tough, flexible material making up skeleton/part of skeleton 4. Functions as strong, flexible rod that muscles can pull on B.Neural crest = group of cells that develop from nerve cord 1. Develops into: a)Portions of brain & skull b)Certain sense organs c) Parts of pharyngeal pouches d)Some nerve fibers and their insulations e)Gland cells C.Also have: 1. Internal organs a)Ex. liver & kidneys 2. Heart & closed circulatory system II. Characteristics of fish (24,000 species) A.Live in aquatic environments 1. Fresh, salt, & transitional water B.Features provided basics for structural development of land animals C.Some fish developed jaws 1. Some have lungs D.Jaws - found in most fish 1. Anterior to gill arches 2. Allowed to eat larger prey 3. Grasp prey w/ teeth 4. Formed by gill slits E.Most have paired fins - Used for balance, steering, & propulsion 1. Pelvic & pectoral fins = balance a)Pectoral can also be used for fine movement 2. Caudal fin = propulsion 3. Anal fin = stabilization 4. Dorsal fins = stabilization 5. Body moves in S motion a)b/c contracting large area of muscles on body F. Scales 1. Ctenoid scales = cover body of most bony fish a)Perch 2. Cycloid scales a)Made of bone & skin b)Thin & flexible c) Salmon & carp 3. Placoid scales a)Sharks & rays b)Made of tooth-like substance c) Rough & heavy d)Vascularized 4. Ganoid scales a)Diamond-shaped b)Made of enamel & bone c) Sturgeons & gars G. Gills - Allows for respiration in H2O 1. H2O enters mouth 2. Gasses diffuse as H2O passes across gills 3. Made of gill filaments - Very vascularized - Where gasses are exchanged a)Contain lamellae b)Able to exchange 85% of dissolved O2 in H2O w/ blood 4. Some fish have operculum = boney protective covering over gills a)Also aids in pumping H2O from mouth to gills 5. Lungfish have structures similar to lungs a)Instead of gills 6. Eels breathe thru skin when not in H2O H.Circulation 1. Have closed circulatory system a)As do all vertebrates 2. Heart → gills → body → heart 3. Most have 2 chambered heart a)Atrium = receives blood from body b)Ventricle = pumps blood to gills & rest of body I. Feeding and Digestion A. ancient fish most likely filter feeders or Scavengers B. most fish swallow prey whole 1. Goes thru esophagus 2. To stomach a. Begins digestion 3. Some have pyloric ceca a. = pouches that secrete digestive enzymes b. At junction of stomach and intestines c. Food then travels to intestines - Where most of digestion occurs d. Liver, pancreas & gallbladder add digestive enzymes 4. Cannot make some a.a. So have to get in diet J. Excretion 1. Occurs with kidney’s a. Filter materials from blood b. Made of nephron’s - Filtering unit - Helps maintain salt/H2O balance - Also removes cellular wastes from blood K. The brain & senses 1. Have spinal cord & brain 2. Cerebellum a. Coordinates movement & balance 3. Olfactory bulbs a. Sense of smell 4. Optic lobes a. Deal w/ color vision 5. Cerebrum a. Coordinates info from other parts of brain 6. Medulla oblongata a. Controls internal organs 7. Lateral line system a. Enables fish to detect movement in H2O b. Also helps keep them upright & balanced L. Reproduction 1. Most reproduce w/ external fertilization a. Happen thru spawning = releasing eggs/sperm at same time in same location b. Developing embryo gets food from yolk of egg 2. Some have internal fertilization (cartilaginous fish) a. Viviparous = give birth to live young - Nourished w/ placenta b. Oviparous = release egg casings (shell) - Eggs hatch later c. Ovoviviparous = egg hatch inside body - Give live birth d. Ex. sharks 3. Most show no parental care a. A lot of egg/young eaten b. If external fertilization form millions of eggs 4. Some fish show parental care a. Usually males b. Ex. sea horse, sergeant majors M. Movement 1. Most have streamlined shape & produce mucus on body a. Reduces friction 2. Have swim bladder a. Gas-filled sac b. Allows fish to control depth in H2O c. Modified lung - Changes air amount to change depth d. Can also be used as amplifier for soundwaves Diversity of Today’s Fish I. Jawless fish (Agnatha) A.Hagfish 1. Jawless, eel-shaped fish 2. No scales 3. No paired fins 4. No bony skeleton a)Have notochord thru-out life 5. Have gills 6. Live on seafloor a)Feed on soft-bodied invertebrates & dead/dying fish 7. Almost blind a)Rely on sense of smell to find food 8. Enter fish by mouth or scrap hole on side of body a)Eat internal parts of fish b)Leave sac of skin & bones 9. Produce slime as defense mechanism B.Lamprey 1. Jawless, eel-shaped, no paired fins, no scales or bony skeleton a)Retain notochord 2. Have gills 3. Parasite a)Attaches itself to side of fish w/ sucker-like mouth b)Drills hole in fish w/ tooth-like structures on tongue II. Cartilaginous fish (class Chondrichthyes) = skeleton made of cartilage - Has Ca deposits making cartilage stiffer - Ex. sharks, rays, & skates A.Characteristics 1. Many species have several rows of teeth a)New teeth move forward as broken/lost 2. Top predators a)detect prey kilometers away w/ smell b)Use lateral line to detect H2O currents c) Good eyesight d)Use sight to get prey 3. Have placoid scales 4. Some sharks (whale sharks, basking sharks) are filter feeders a)Whale shark = largest living shark b)Some eat mollusks 5. Skates & rays a)Live on bottom of ocean b)Enlarged pectoral fins c) Eat mollusks & crustaceans d)Tails might contain electric organs e)Others have venom on tails 6. Have internal fertilization III. Bony fish (class Osteichthyes) - 2 groups A.Ray-finned fish 1. Have: a)Bony skeleton b)ctenoid/cycloid scales c) Operculum d)Swim bladder 2. Have thin, spine-like structures supporting fins a)Can change shape of fins 3. Different body shapes for different environments 4. Most fish a)Ex. salmon, trout, catfish, perch, etc. B.Lobe-finned fish 1. 8 species alive today 2. Fins are muscular w/ joints a)Makes fins more flexible b)Stronger than ray-finned fish c) Have muscles & bones 3. Ex. lungfish a)Burrow during drought & breathe air b)Live in streams & swamps in Australia, S. America, & Africa c) Breathe w/ gills/lungs d)Closest relative to terrestrial vertebrates. 4. Ex. coelacanths a)Thought to have been extinct (caught one in 1938 & 1997) b)Breath w/ gills c) Swim bladder filled w/ fat d)Live in deep H2O of Indian ocean IV. Evolution of Fish A.1st fish = jawless & toothless 1. Did have gills 2. Like vacuum cleaner on floor of ocean V. Ecology of Fish A.Good bioindicators 1. #’s usually decline b/c of habitat alteration a)Ex. dams blocking salmon migration b)May build “stairs” for salmon 2. pollution