PSL280 Marine Mammals

Protect and supportlocomotiondetermine sizecreate precursors for RBCstore lipidstimeline of biochemical events after death

Large cervical and lumbar vertebrae8 true ribs, 4 false ribs, 3 floating ribsphocids: cannot rotate pelvis-flop on landotariids: can rotate pelvis-walks on landacromion attached to scapula for strong muscle attachments

7 cervical vertebrae-2 or more may be fused-fusing causes stability (sperm whale)-unfused causes flexibility (beluga)ribs are poorly articulated with thoracic regionodontocetes have well defined sternal ribsmysticetes have poorly defined sternal ribsvestigial pelvis with no hind limbstail divided into 2 flukes-very compresses vertebrae with cheveron extending to notch of fluke-counter current system for thermoregulation-no blubber in flukeflatter bones compared to humans

Large thorax, small lumbarsternum= large flat bone with no fused elements-3 ribs are attached, rest are floatinglittle/no hind limbs

Short necklots of attachment points at caudal, thoracic and lumbar section10 ribs loosely associated with the sternum (14 in total)smaller scapula than river otterswebbed skin between toes doubles surface area of foot

Little skeletal adaptions, mostly muscularpaws like pans/snowshoes for swimming and snow-paddle with forelimbs, hind legs dragging behindvery strong neck muscles

Water is 800-1000 times denser than air-60 times more viscousneed to overcome drag, buoyancy, pressure gradient and thermoregulationterrestrial mammals have a heavy body skeleton to overcome gravitymarine mammals and long and slender

Phocid use pelvic oscillation-slow, but steadyotariid use pectoral oscillation-fast, but unsteady-power/paddle/recovery technique

Humpback whale: pectoral fin is 25-35% of the total body length-tubercules on anterior edge of the fin help lift it out of the water-gives fin a scalloped appearence-one of the most agile cetaceans

Cutaneous layerthinner blubberlayer of ligaments from caudal keel and sides of finstough, dense fibrous tissue making up flukesinner core contains the counter-current systemcompressed caudal vertebrae extending to notch

Moving caudal fin up and downFlexing fluke out and inwardUpstroke: 2 epaxial muscles-multifidus extensor-longissimus extensorDownstroke: 2 hypaxial muscles-flexor caudae lateralis-flexor caudae medialisHead up when tail is up, head down when tail is downConserving elastic energy-huge elastic/connective tissue in flukes-transmit propulsive forces-energy stored as elastic strain energy

Use caudal oscillation-displaces in a vertical manner-strong powerful strokesAdult keep pectoral fins close to bodyYoung seen to paddle with pectoral finsFlippers usually used to flip and spin while floating-also use to "walk" along the groundManetees have no fluke, dugongs have 2Caudal find to steer, bank and roll over

Pelvic paddling: hind limb propulsionPelvic undulation: propulsion while diving

Head and chest out of waterUsed for feeding/first step to escapeFore limbs folded on chestAlternating /simultaneous strokes of hind limbsMay have hind limbs out of water and swing tail laterallyMore limbs out of water = warmer

Head and shoulders out of waterhind limbs alternating/ simultaneously paddlingFore limbs held across chestSwimming from place to placePrep for diving or submerged at high speeds