Lecture 9: Mammals
Lecture 9: Mammals BISC 2467
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This 11 page Study Guide was uploaded by Lareb Notetaker on Tuesday March 1, 2016. The Study Guide belongs to BISC 2467 at George Washington University taught by Edward Murdy in Spring 2016. Since its upload, it has received 35 views. For similar materials see Marine Biology in Biology at George Washington University.
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Date Created: 03/01/16
9. Mammals Cetaceans: unique and highly specialized group ofmammals. They haveproliferateforlimbs, much reduced back limbs. Highly adapted for life in marine environment. Pinnipeds: carnivorous aquatic mammals including seals walruses and similar organisms having finlike flippers to use as organs of locomotion. Sirenians: slow, large, and passive mammals of tropical, subtropical mammals. Large thick bodies that indicate their heritage to long ago relatives such as elephants. Elephants and sirenians have a close related ancestors. All these mammals adapted to marine environment had to comeover afewproblems. They’reancestors were land based, they moved from land to the sea. First they had to be able to move through a viscous type of medium(viscous fluid). Thesolution to the problem is to develop a streamline body shape. You minimize number ofappendages you have. Marine mammals some havelarge anterior appendages (flipper fins). They havevery limited appendages on the back part of thebody. of body heat. Marine mammals have developed densefur orblubber ormix of both to reducebody heat loss. Theyseloss have a large body size which generate alot of internal heat. Minimized appendages so you’re not losing heat through long and large appendages. Circulatory system that conserves heat, countercurrent heat exchange current - how they overcome body heat. Third problem is that they’re mammals and breatheair, so they have to come to surface to breath but haveto hunt for food underwater. They havephysical and physiological adaptation to allow extreme breath holding. Atthevery top youseeElephants,ManateeandHyraxes.Closesliving organismto a ManateeisaHyraxwhichisalandbasedfurrycreaturethatlivesinthemountainsof Africaand theMiddleEast.Butif yougobackin time,allthreehadacommon ancestor.CetaceansclosestlivingrelativeisaHippopotamus. Seals, Sea Lions, Walruseshave a commonancestor withraccoonsandskunksso they’re offthe dog/bear branch. Allthesemarinemammalsevolved fromlandbased formandmostofevolutionoccurredinthelast50 -60 million years. Extinctions that haveoccurredintheworld,lastmajorextinctionwasabout60millionyearsagoat the end of the Cretaceousperiodwhenwe lostthe dinosaurs. differentanimalssuch as mammalswereabletofillinvoidleftbydinosaurs Odontoceti :carnivorous. Mysticeti:baleen:filtering/straining mechanisms. Feedon thingslike krilland small fishes.PassiveCarnivorous,notactivelyseekingoutprey. Livebirth,parentalcare(feedingoftheyoungbymemoryglands),hair(whales don’tapplehairybuttheyhavesomeresidualhairfoundinhead),warmbloodedaka homoeothermic - maintainconstantinternaltemperaturewhichrequiresalotof energy,mothersmilk,havealargecaudalfin/tailfin - usedforpropelling Livebirth,parentalcare(feedingoftheyoungbymemoryglands),hair(whales don’tapplehairybuttheyhavesomeresidualhairfoundinhead),warmbloodedaka homoeothermic - maintainconstantinternaltemperaturewhichrequiresalotof energy,mothersmilk,havealargecaudalfin/tailfin - usedforpropelling themselves(Caudalfinisdivided intorightand leftfluke- primarymeansof propulsioninwhalesandporpoises.) Leftsidewehavetoothedwhales,rightsidearetheBaleenWhales.Allthewhales ontherightsideareBaleenwhalesandaresignificantlylargerthanthetoothed whales.Largestlivingwhaleisthebluewhalegetting upto a100ft.in length comparing thesizeto averylargedinosaurs(it’sactuallybigger).Spermwhaleis the largestof the toothedwhale, orca isalso a toothed whale. Odontoceti: good hunters, feed on squids (significant part of diet of most whales), feed on fishes and some toothed whales (orca in particular) feed on small mammals and sea otters and seals.Gooddiverscangointogreatdepthsinordertocapturefood.Spermmalewillroutinely divetooverathousandmeters.Recordedasdeepas2800meters,canstayunderwaterfor2 hours.Smallerwhales(porpoisesanddolphins)candiveuptoa100metersandstaysubmerged for 5-10minutes.Allofthetoothedwhalesareabletoproduceanddetectsound.Theyhave anatomical adaptations toproduce and decide ultrasonic plates byusing echo location (like bats).Burglarious,havesocialstructuresoyoufindthemingroups.Averageliveis20 -40years somecanlivelonger.ReproductionRatesarelow,adultsdon’treachsexualmaturityuntil20 yearsold.Gestationperiodforpregnancycanbefrom8to16months.Soproblemwithlow populationofwhalesisdecimatedbyhuntingisthatittakesalongtimeforthemtoregaintheir formal population structure since they’ve been under protection nowfor 40-50years. Sperm Whale:largestof the toothedwhales, can reach lengthsof almost60feet (18meters)andweighupto45tons.Themalesarelargerthanfemales,foundall overtheoceanbuttendtobefoundmoreintropicalandsubtropicalwaters.Head housesaverylargereservoir,containingasubstancecalledaspermaceti(oily waxy substance) and thisiswhatthewhalerswantedto collectwhentheycaptured them. MobyDickwasa sperm whale. Have a substancecalled Amber Gris, which is a substance thatissecreted in theintestine of spermwhalesand itissecreted around thesquidbeaks.Feedprimarily onlargesquids,(everythingdigestedbut the beaks). In order to keep sharp beakfromhurtinginternaltissuesof sperm whales,theamber grisrecreatesaround thebeak andhardensitand won’tdo damage.Whalersharvestedambergrisandusedinperfumes,whalersharvested all partsofwhaleand utilized foreven food. Thespermacetiorganisusedforecholocation.Turnedintocandles,thewaxy substance. Large teethonlowerjaw, but none onupperjaw because they fit into sockets and this is because they feed primarilyonsquidwhichare slippery and Thespermacetiorganisusedforecholocation.Turnedintocandles,thewaxy substance. Large teethonlowerjaw, but none onupperjaw because they fit into sockets and this is because they feed primarilyonsquidwhichare slippery and slimy, the sockets helpto hold ontosquidbetter. Beluga: white in the adults, as caves they’re pink-ib srown.Foundonlyinthe arcticand traveland congregatein largegroupsasmany as100individuals. Found close to shore and in the summermonthstheytravelup estuariesto give birth.Becausethey’refoundclosetoshoreandinestuariesinarctic,they’re preyeduponbypolarbears.Polarbearsarealsomarinemammal. Narwhal:(illustrationof amale) havetwoteeth only inupperjaw.In females these teeth never eruptthroughthe gums. In malesoneof the twowillerupt throughthe gumand keepgrowingaslong asthe whale isalive. Some timesboth teeth erupt(quite unusual). Usually,male’sonlyhave a single tootherupting throughthe jaw. Large tooth issexualselection- malestusslewithoneanother and whack teethagainsteachother(likefiddlercrabs). Orca(killer whale):largestdolphin(familydalphinity - which includedolphins, pilotwhales,orcas).Malescangrowupto32ft.longandweigh8 -9 tons. Femalesare smaller can reachabout20somefeetandweigh4 tons. Found everywherebutmoreabundantin coolerwaters.Travelin groupsofrelated individuals(mother,offspring) in search offood. Orca willfeed onfishes,seals, sea lions, sea otters, small whales. Commonlybreachmeaningtheyleave thewater not known why they dothis, assumed they doitforcommunication. Anumber ofwhalesleavethewater and breach Commonlybreachmeaningtheyleave thewater not known why they dothis, assumed they doitforcommunication. Anumber ofwhalesleavethewater and breach Similar butpeople oftenuse termsinterchangeably, butthereare differences betweentruedolphinsandtrueporpoises. Dolphins:conedshapeteeth,pronouncedbeak,curveddorsalfin. Proposes:flator spade shapedteeth, nobeak, triangulardorsalfin, usually are smaller than dolphins.Veryfew species in world, only6. Many morespecies ofdolphins. Echolocation:providesdifferenttypesofinfotothesenderofsoundwaves,if youaresendingoutsoundwavesyouwillfindoutwhentheechocomesback to you the directionthatitiscoming from, the change in frequencythattells yousomethingaboutdistancethatitisbouncingbackfrom,amplitudewill change,andthereisalapsed time.Asthey swimabout,constantlymovehead backandforthforagoodfeelofecholocation. Sound wavesemanate through anorgancalleda melon - helpsdirectsound waves,soundwavesgooutatstrikean objectlikeaprey,soundwaves bouncebackfromfoodobjectandenterthelowerjawwhichpicksup returningsoundwavethengoingtotheinnerear,thenthebrainwhich translate allthe information(samethingasaspermacetiinspermwhale). Has very good vision,butyoucan blindfold itand itcan movearound,feed unimpeded.Primarilyusesecholocationfortravelingandfeeding Mysticeti:noecholocation.Includelargestanimal,thebluewhales.They usebrushliketriangularplatescalledbaleenwhichhangfromtheroofof Mysticeti:noecholocation.Includelargestanimal,thebluewhales.They usebrushliketriangularplatescalledbaleenwhichhangfromtheroofof the mouth. These baleenplatesfilteroutplanktonand isnotjustlarge zooplankton,butcanbesmallfishesandsquid.Baleenplatestrap larger organismsandtheyusetonguetolickplatesandgetthefoodofthebaleen platesandthenswallowthefood. Baleen whales have a number of different feeding techniques: Ram feeders, swim with mouth opens (Baskin and whale sharks capturing organisms - food stuffs on their baleen plates).Blue whales are intermittentram feeders: swim around and once in a while open their mouths collect a swimming pool sizevolumeofwater, closetheirmouthandpushwateroutagainstbaleenplates, collect food with their tongue. Grey whales go down to the bottom (substrate) and feed on benthic organisms, suck upsubstrateonbottomandfilterthroughbaleentocapturefoodandspiteverything else out. Humpback whales: use bubble nests to capture their food. Swim under school of fish, and start at the bottom and swim in a serial circle toward the surface emittinggas bubbleswhichscaresthefishandthefishtendtocongregateclosertogetherandthe humpbackwhalecomeuptothesurfaceandeattheswarm schooloffish. Humpback whalescommonlybreachingin water.Communicatewithother whalesperhaps. Usebubbleneststo capturetheirfood.Swim under schoolof fish,and start at the bottom andswim in a serial circletoward the surface emitting gasbubbleswhichscaresthefish andthefish tend to congregateclosertogetherand thehumpbackwhalecomeup to the surface and eat the swarm school of fish. Beached fin back whale. Look at baleen. Beached fin back whale. Look at baleen. Polarbears:feedalmostexclusively onsealsfoundin the ocean. Pinnipeds:translatesto featheredfoot. Have fourappendages,and featheredwootreferstotheirwebbedflippers.Partofthelifecycleis terrestrial, move onto landto breedandrest(ice or land). Distributed in alloceansbutfoundin higherlatitudesand travelin herds. Sea Otters:belongtoterrestrialfamilythatincludesweaselsandferrets. Sea Lion:move around muchbetter thansealscan on land ElephantSeal:greatlyenlargedprobasses,typicallyfoundinherdsor groups. Steller Sea Lion:hasexternalear. Pinnipedshave large size and thick fur and blubberto restrain body heat,streamlinedwithwelldevelopedflippersespeciallyfront flippers.Feedprimarilyonfishesandsquids,walruseseatshellfish (molluskstheydigupwiththeirtusks)somepinnipedsthatfeedon penguins(leopardsealeatspenguinsandsmallseals). Howto tellpinnipedsapart;?SeaLionshaveexternalearswhereas true sealsdo not, sea lion have welldevelopedhind flippersthey’re ableto rotateforwardswhereassealscannot.Walrushasalargetusks and they’repretty hairless,onlymalewalrusesthathastusks. Sea Lionsapartfrom Seals:externalearand rear flipperscan rotate forwardandfront flipperscanrotatebackwardsenablingSeaLionstomoveaboutonlandthanSeals becausetheirfrontandbackflipperscannotrotateandtheyhavenoexternalears. Very gracefulin waternoton land. Sea Otter:membersof the Weaselfamily, lackblubber buthave extremelydense fur(densestfurofanyanimal)constantlyeating(about25%ofbodyweighteach day).Needtoeatthismuchfoodbecausethey’rehomeothermicandneedto generatealotofheat.They’realsotoolusers,sotheyfeedonseaurchinsand bivalvesandtoopenupabivalvetheyputastoneontheirbellies(lieonback)and with their hands(longfingers) they grabthebivalvedand smash onrockuntilshell is crush and eatthe inside. Sirenian:include manatee,dugong, and extinctstellar sea cow which wasfound in the late 1800’sin thenorth pacific andwithin30yearsofbeing describedasa new sea cow, it become extinct due to overhunting.Theydidn’t swim very quickly, and super sluggish, theylive in shoreso easy to see, catch, ad kill.Onlyherbivorous aquaticmammal.Spend entirelifein water,Dugong in Indian and pacificocean onlyonespecies.ManateesfoundintropicalAtlantic(onlythreespecies - Caribbean,Amazonian, andcoast of west Africa).Manatees can dive and spend about20 minsunderwater.Reason fordiving isthey feedingon seagrass. Can live upto50 - 70yearsbuttheirfecundityisquitelow.Theydon'treachmaturityuntil aboutage10,theyproduceonly 1 calfevery fiveyearsorso. Called gentle giants,can get quitebig.10 ft longand weigh1000lbs. But their non-aggressiveand they justliketo munchplants.Spendmostoftheirday feeding,6 -8 hours a day feeding in order to get sufficient nutrition. Tell them apartby tailfin.Dugonghasacretaceoustailfin (likeawhale)whereasthe manateeisrounded.Thefrontoftheheadisdifferent. Problem they’re trying to overcome is, How do you hold breath and havesufficient oxygen to hold breath Problem they’re trying to overcome is, How do you hold breath and havesufficient oxygen to hold breath and won’t die. Can hold breaths for 2 minutes (very good). Theseanimals can hold breath for longerto be successful hunters. When they breathe in, get abreath of air, the C2 is rapidly transferred to the blood. The transfer rate it much higher in the marine mammals than in humans. Wetransfer about 15% of available O2 do. Even though they’re larger animals they have more blood than humans perpound. They have veryns efficient hemoglobin, found in blood cells, and the hemoglobin holds the O2 and releases it as necessary. Can release almost a 100% of O2. Whereas the human can only realizeabout 30-40%. Extra blood serves purpose, to be able to carry moreO2. Myoglobin, like hemoglobin in blood cells. But myoglobin are in muscle cells. Concentration in marine mammals is very high. When diving they can collapse their rib cage and lungs to reduce buoyancy to dive deeper and quicker. Also able to reducemetabolic rate, and heart rate decreases. Thereforethe need foroxygen is decreasing. They'reable to shut off blood supply to parts of the body. They're less sensitive to accumulated C)2. If you'reholding your breath and you've reached limit you could hold, the thing forcing you to the surface or you'll feel much better underwater if you release air in your lungs because of the C)2. CO2 concentration is so high if you releaseit you will have a momentary resting. Brain is sensitive to CO2. Seabirds: also part of the Nekton.Birds,that are adapted to life in the marine environment. How does a seabird differ from a non sea bird? They live longer, breed later, fewer young thanotherbirds.Alsospendquiteabitoftimeinparentalcare.Mostseabirdspeciesnest in colonies which can vary in sizefromafewdozen individualsto amillion birds.Man speciesarefamousforundertakinglongannualmigrations.Somewillgofromalmost South Pole to all the way to the North Pole,vice versa.Feed at both the ocean surface and belowit,someare abletodiveintothewater,someareveryadaptatmovingunderwater. Can be pelagic: go out into blue water areas.Some are coastal. Penguins: have countercurrentheat exchange system where arterial blood warms the Venus blood/vessels. Helps heat exchange in the wings and the feet. Albatrosses: capture squid, fish. Can fly for long distances, very long wings. Pelicans: large stocky billed birds,large pouch under bill used for capturing fishwhile divingunderwater. Dulls, auks, puffins: Feed on fish, just about anything. 250/8500areSeabirds. Monogamous:pairbondandstaywiththatmatefortherestoftheirlife. Courtship displays: dancing, frigate birds have relishpouchtheyinflate to attractmates. Emperor Penguin :largestof the penguinsabout4ft. tallandweigh ~70/80 lbs. Live and breed in Antarctic continent. Usually huddle togetherallthe maleswiththeiregg. Albatross:gliding bird, travelsgreatdistances. Severalhave beentaggedand havetraveledasmanyas9Kmilesinsearchoffoodbeforecomingbacktothe nest. FrigateBirds :longwingspan. Harassothersea birdsthathavecaptured other fooditeminattemptstotrytogiveupfooditemevenifthey’veswallowed fooditemmakingthemvomitituptoeatit.Theyhavegoodhomingcapacity, the ancientPolynesianswouldtake onraftsand sendmessagesback(like pigeons) Black-backedSea Gull:largestofthe gill,foundin NorthernAtlantic. pigeons) Black-backedSea Gull:largestofthe gill,foundin NorthernAtlantic. low tide in the intertidal area of estuaries, coast line, also found in salt marshes estuaries. Most species are found on marine shores, salt water shores, and also shorebirds found in fresh water wet land areas, many use this fresh water wet land area during migration. Undergo very long migration. Can migrateover very long distances. Migratory paths they use are influenced by geography and wind. Some migrations are thousands of miles. Thought to have some kind of orientation for purpose consoled by sun, moon, positioned stars, magnetism, and even old factory cues. Morphologically how do shorebirds differfrom seabirds? Shore birds are smaller and weigh acouple ofounces and largest ones can weigh up to a pound. Another key feature is that they don’t have any webbing on their feet. Seagull has webbed feet, shore bird does not (sand piper). Have distinctive bills, are very long and stout. Red Knot: extremely long migration traveling about 15,000 km from the tip of South America Tierra Delfuego all the way up to the arctic whereit breeds in summer time in the northern hemisphere. In fall it migrates back to South Amer. As it moves north from Tierra Delfuego, it will hopscotch across coastal areas in South America stopping in numerous places. It stops in the Mouth of DelawareBay usually by early April they make it here to feed on Horseshoe crab eggs. Early April is when the Horseshoe crabs climate change, becauseof warming of the seas, the Horseshoe crabs are starting their migration to Deleware bay earlier than they havein the past. TheRed Knot aremissing some of the time the Horseshoe crabs responding. Red Knot population size is decreasing and not on endangered species list all as a consequence of global changeupsetting established patters different animals havehad. Oystercatcher:very stoutbeakto feedonoysters.Beakseverredindentured muscletofeedonoyster. Sea Turtles: migrate from feeding grounds tospawninggrounds and some of these Sea Turtles: migrate from feeding grounds tospawninggrounds and some of these migrations are lengthy indistance.The green turtle population thatfeeds off of coast ofbrazilandmovestomiddleofatlanticinanislandtolayeggs.Thereare7species ofseaturtles.All7areconsideredendangered.Tastytoeat,easytocatch,manyyears therewere noregulations.Migrationthereforenotfoundwithinoneparticularcountry crossing many different boundaries sohard to regulate. Green turtle is herbivorous and feeds on sea grasses and sea weeds. Camps Rigly turtle is invertebrate eater. Leatherback turtle eats jelly, siphonophores. Jellies are mostly water, not a whole lot ofnutrition.Differentfromotherseaturtlesbecauseitlackshardbonyshell. Leatherback:Largestoftheseaturtles,maturemalesandfemalescanbe morethan6ftinlengthandcanwayalmost2,000lbs.Lackshardbony shell has a carapace whichis comprisedofoily connective tissue.Found allovertheworld.Mostmigratory.Bestswimmersofallseaturtles. Longfrontlegs(paddlelike), femalenestingonbeach baby,justhatchedbeforesomeoneeatsit Green Turtle:adultcanreachabout3 ft.can weighup to 350lbs. Herbivorous,feedonseagrassesandseaweeds.Globallydistributed, generallyfound30degreesNorthand30degreesSouth(Horse Latitude).Reportedfroma140differentcountriesglobally.(Pictures depictsononcoralreef)Canfindgreenturtlesaroundcoralreefsdueto growthofalgae. Sea Snakes:highlyvenomous, extremely toxic venom, fortunatelyvery ofattacksonhumansresultingindeath.Snakescanspendentirelifein sea. Give birth to live youngcalledviviparous snake. Oneexceptionis Sea crate:layseggson land, makesa whole and laysitseggs.Wiggles there backintotheseaafterdonelayingeggs. Saltwater Crocodile:foundfromAustralia to India. Hasa high tolerance forsalinity. Can undergolongoceanic migrations. (Malaysia - CoCo’s Island)Canswim longdistances using longtail as apaddle.AmericanandNilecrocodiledonothavesaltwater tolerance thattheIndo-Pacific (saltwater) crocodilehas- foundin coastalareas,rivermounts,freshwaterriverareas,swamps,very dangerous.Ifyouseeonethereismorethanone.Largestspeciesof crocodileand canreachupto 20ft.
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