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58 Cards in this Set
- Front
- Back
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What is comparative anatomy
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Classifying animals based on their homologour and analogour structures
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What are homologous structures?
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Those identical by descent - reveals evolutionairy history
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What are analogous structures ?
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Identifiable by function - reveals action of natural selection
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Who was Pierre Belon?
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16th Century French Naturalist who compared skeletons of humans and birds and worked out dophin embryos have lungs
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Who was Jean - Baptiste Lamarck?
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19th Century French Zoologist who based evolution on acquired characteristics based on environment interactions.
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Who was richard owen?
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19TH Century Britist Zoologist. First director of the natural history museum and disected all animals that died at london zoo.
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Who was Charles Darwin?
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19th Century British Zoologist. Developed theory of natural selection. No knowledge of genetics but used comparative anatomy to support his theory.
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What are the three constraints of anatomy?
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Evolutionary history, embryonic development and environment
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What are the adaptations of the class chondrichthyes (cartilaginous fish)?
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Loss of bone (lightens body, increses movement),
Holocephali - single gill opening Elasmobrancii - Multiple gill openings |
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What are the sharks adaptations?
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Cylindrical bodies, gill openings on side of head
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What are the rays adaptations?
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Flattened bodies, gill openings on the side of head
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What were the adaptations of Paleozoic sharks?
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Found mostly in freshwater. Notochord. Neural arches to protect spinal chord. Less scales and broad based skins.
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What were the adaptations of early mesozoic sharks?
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Heterodont teeth (anterior teeth had sharp cusps and posterior teeth had blunt cusps). Narrow fins. Heterocercal tail and Hemal arches.
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What were the adaptations for Late mesozoic sharks?
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Third chondricthvan radiation - produced modern forms. Sensory rostrum. Calcified vertebrae to replace notochord and thicker more complex teeth enamel.
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How many shark families and orders are their?
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30 families, 8 orders.
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What happens to a shark embryo in its early stages?
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Undergoes discoidal clevage. It has a yolky cytoplasm.
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How does a sharks embryonic yolk become it's gut?
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A blastoderm grows over the surface of the yolk to form a yolk sac. An endomesoderm arises beneath the blastoderm and differentiates to form endoderm and mesoderm, leaving a ectoderm at the surface.
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What is neurulation (nerve formation) in shark embryos?
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It is where cells and nerves form. A flat sheet of cells forms in the endoderm, lateral plates form in the mesoderm and tubes and neural crest cells are formed in the ectoderm.
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What is within the body cavities?
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Hear cavity, intestine cavity seperated by a transverse septum which has a confluence of veins that the liver grows off.
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How to tissues form in shark embryos?
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Embryos have germ layers. These give rise to tissues. Epithelium and connective tissues, muslce tissue and nervous tissue.
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What are ectodermal placodes in sharks?
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They are thickening of the surface of the ectoderm and sink inwards to form sensory receptors, sensory nerves and some cranial nerves.
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What are HOX genes?
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They determine what is expressed from the anterior to posterior axis of a body. They are expressed in early development
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How many HOX clusters do cephalochordates have?
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1
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How many HOX clusters do tetrapods and elasmobranchs have?
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4. Two cluster duplications.
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How to shark move in water?
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Via lateral undulations anterior to posterior.
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How do slow swimming sharks swim differently to fast swimming sharks?
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Slow swimming sharks with with Anguiliform locomotion where the body bends more than half way compared with Carangiform locomotion in fast swimming shark such as great whites and tiger sharks.
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What is an problem for shark movement?
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Dragggg (like a phoenix) and turbulence
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How do sharks cope with drag?
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Streamlined teardrop shape and integument skin with denticles with placoid scales.
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What is a sharks skeleton made up of?
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Cartilaginous bone. Ancestors had bones which have been lost in the modern shark, although they are retained in teeth and scales.
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How do fins of shark help it?
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Dorsal and Lateral fins stabilse the body and pectoral fins initiate rising or sinking.
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How do sharks keep buoyant in water?
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Asymmetrical tail generates lift. Oil filled livers.
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How are sharks adapted for living in a cold water environment?
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Regional Heterothermy - different parts of body are different temperatures. Swimming muscles are alot warmer. Brains and eyes are marginally warmer.
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How are shark gills adapted?
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They have a counter current blood flow.
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What is Ram ventilation?
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Sharks have to move forward to drive water into the glls. 24/400 known species of shark have to ram ventilate.
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How do some sharks ventilate them selves?
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A dual buccal pump, used by ancient sharks and still used by most sharks. Some sharks have to buccal pump and cannot ram ventilate.
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What is another method of respiration other than ram ventilation and buccal pumping?
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Culaneous respiration. dogfish gains less than 5% of its oxygen through it's skin.
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Why do sharks not have 6 aortic arches?
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They hav 5 (II-VI) as the first gill arch is replaced by spiracles.
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How do specialist sharks feed in water?
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Using suction or filter feeding.
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What are the two types of shark jaws?
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Amphistylic (joined in one place to skull). Hyostylic (jaw attached in two places) allows hyomandibula to happen
(jaw swinging forward) such as in great white sharks. |
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What is special about sharks teeth?
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They have a ligamentous band underneath them. Rapid teeth replacement (7=8 days in young sharks)
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What are heterodont sharks?
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They are sharks with different types of teeth, such as port jackson shark which has specialised crushing teeth for spells and molluscs
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What else other than breathing is a buccal pump used for in sharks?
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Suction feeding. e.g. in carpet sharks
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What are the digestive adaptations of sharks?
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J Shaped stomach and short intestines with a spiral valve.
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What is in a sharks hindbrain?
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Amygdaloid nucleus for fight/flight and cerebellum for muscle coordination. Connected to the spinal chord via a brain stem.
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Where does sound and motion detection come from?
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Hair cells in the lateral line system, auditory system and vestibular apparatus.
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What does the lateral line system in sharks do?
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It detects stationairy objects, runs throughout the shark and into its sensory rostrum. Detects disturbances in water and water currents too.
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What is the structure of a sharks ear?
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Three D shaped canal set at right angles lined with hair cells, filled with fluid. Responds to acceleration.
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How do sharks detect sound without a swim bladder?
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shark is made of water and so tissues conduct similar to water and so soundwaves pass directly into tissues of shark. Most sensetive to low frequency sounds such as prey struggling.
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What is electro reception?
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It is pores filled with electrically conductive jelly that detect electrolytes such as blood in prey, hidden prey in sand and lon-rich seawater moving in earths magnetic field, useful for navigation.
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What adaptation do embryonic sharks have?
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They develop electrical fields produced by potential predators and cease moving and breathing to avoid detection.
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Why does a shark prefere seals to otters?
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Its teeth and jaws sense the nature of food. Rather eat blubber than fur.
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What does sharks midbrain have?
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Optic lobes that are adapted to work in water by having contracting and dialating iris', having lenses that move to focus not change shape, have rod and cone cells.
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What does a sharks forebrain have?
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Olfactory organs, cerebral hemisphere (cognition, home ranging and behaviour). Hypothalamus, for homeostatis and hormones. Pituitary gland to control the endocrine system.
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What adaptations do sharks have for chemoreception?
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Olfaction - detects chemicals, but is imprecise. Taste - precise analysis.
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Why do sharks have a urogenital system?
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Cause it arises from the same embryonic tissue and so the urinary and reproductive systems use the same ducts.
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How to sharks keep osmotic balence?
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They are osmo conformers, having high concentrations of ions in their body so they do not loose water to the environment.
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How does a shark cope with excess salt?
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It has rectal salt glands that eliminate salk from it's body, forced into intestines and eliminated with faeces.
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How are euryhaline (sharks who move between fresh and salt water) adapted?
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Reduced urea concentration, with pups having similar levels to their mother.
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