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PSL280H1 (1)

PSL280 textbook notes .docx

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MOVEMENT THROUGH WATER PINNEPED Otariid/eared seals  pectoral ossilation/fore limb swimming  move them like birds do in flight  fore limbs have twice the SA than the pelvic limbs  power/paddle/recovery phases  allows for fast swimming with the capability to do tight turns butinstable trajectory Phocids/earless seals  pelvic ossilation/hind limb swimming  hind limbs are the major source of propulsion – while forflippers for steering in paddling motion  move in side to side manner moving a lot of water= thrust  not as fast as Otariid swimming but more stable Cetaceans  elbow situated near body  Humpback whale- 1/3 length of its body; helps with high maneuverability while feeding  Long and narrow  Has tubercules on anterior side which help as lifting devices to control water over the fin to help maintain lift  One of most agile and mauverable cetaceans in existence Caudal Fin and Flukes  Outside cutaneous layer aka skin  Think blubber layer  Ligament layer from caudal keel and sides of caudal fin  Flukes made mostly with inner core of dense touch fibrous tissue with envelope of ligaments and numerous blood vessles to help retain heat in countercurrent direction  Compressed caudal vertebre to notch of flukes – flat and act as support  Shape varies Cetacean Propulsion  By flexing and extending several muscles which move the fin up and down and flexes the flukes in or out  Up and down movement=caudal oscillation- similar to how tuna swim  Do this by alternating actions of epaxial and hypaxial muscles  Epaxial- in lumbar region-back  Hypaxial- caudal region- tail  UPSTROKE- epaxial muscles ontop of transverse process extend caudal fin upwards o Multifidus extensor o Ongissimus extensor  DOWNSTROKE- hypaxial that flexes caudal fin downwards and depresses the flukes o Flexor caudae lateralis o Flexor caudae medialis  Instead of metabolically using energy to power, they use huge elastic bands to power the caudal fin  Strong connective tissue around flukes helps transmit propulsice forces  In tendons and connective tissue sheath in the flukes, e~ is stored as elastic strain energy and recovered as elastic recoil- muscles don’t full retract SIRENIAN PROPULSION  pectoral flippers usually near sides of body but young can swim withthem sometimes  used for spinning or turning around, or walking on bottom  caudal oscillation for sudden powerful burst of speed  caudal fin used to steer, bank, roll over  propusiion usually started with upwards swing, then downwards.. as tail goes up so does body and when it does down, so does body Sea Otter Propulsion  pelvic paddling and pelvic undulation  pelvic paddling – o ventral surface up swimming – body partically submerged just head and chest up- forelimbs on chest, while hindlimbs alternate or simutanously stroking water to provide propulsion.. sometimes both hind limbs can be raised and tail circles in lateral movements o ventral surface down swimming- head and scalpula up, fore limbs across chest while hind are alternating or stimutaneously moveing to move the animal o alternating ventral surface up and down swimming – associated with groomingwhile rolling along long axis of body ; only hind limbs provide propulsion for this  pelvic undulation- while swimming in the water… contractions of vertical flexing Polar Bears  few physiological adaptations for swimming- strong limbs for swimming with huge feet shaped as big flat plates  hind limbs usually trail behind while swimming while forelimbs do all the work  forelimb muscles have rearranged to help with this kind of swimming SKELETAL ANATOMY Pinnipeds-  large vertebrae esp cervical and lumbar region- allows for extensive neck and hind limb movement for walking on land  ribs firmly articulated to thoracic cavity- 8 fused, 4 false, 3 floating  lengths of pas and mamus vary with different pinniped species  diff length and size of bones determines amount of surface attachment for various muscles which allows for amount of movement and flexability or strength needed for locomotion Cetaceans-  7 neck vertebrae- 2+ fused that determines stability. Sperm whale has a lot fused therefore stabilized head and allows for streamlining – as its short and rigid  beluga has less fused which allows for flexability
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