Humans: 34% O 2 in lungs 13% O 2 in Myoglobin 41% O 2 Hemoglobin 12% O 2 in tissue fluids

Transcription

1 BI 165- Unit 9 Marine Mammals I. Marine Mammal Adaptations A. Diving Adaptations - the development of mechanisms to interrupt breathing for prolonged dives ex: sperm whale 1 hr to 2,000 depth common (3,500 record) 1. Storage of Oxygen in Tissues Fin Whale Dive: 9% O 2 in lungs 41% O 2 Hg blood 41% O 2 Myoglobin 9% O 2 in tissue fluids (Lung capacity ½ that of terrestrial mammals) Humans: 34% O 2 in lungs 13% O 2 in Myoglobin 41% O 2 Hemoglobin 12% O 2 in tissue fluids Whales have: a. Collapsible ribs allow for lungs to collapse b. Larger hearts: 3x s more blood/unit body wt. (more Hemoglobin) c. 9x s more Myoglobin d. Myoglobin contains 50% more O 2 than Hg e. Greater tidal exchange: 85-90% of the air exchanged in each breathe (human s exchanges only 15% of the air) 1

2 2. Use of Lactic Acid Fermentation (alternative energy source) a. never an efficient use of energy b. causes CO 2 & Lactic Acid build-up in tissue c. no apparent pain or injury 3. Economic Use of Energy Reserves a. heart rate drops b. blood flow shunted to: heart & brain from: digestive organs c. drop in body temp requires less heat manufacture d. use of specialized retia veins & arteries to maintain even pressure at changing rates Metabolic changes are standard dive changes in some & emergency in others (dolphins & porpoises) B. Adaptations to Cold Marine Temp 1. heat or cold transfer in water is 20x that of air 2. All marine waters are colder than normal mammalian temp - extreme water temp of temperate & arctic water - subsurface waters in tropical waters 2

3 3. Methods of heat conservation - higher basal metabolism in whales compared to terrestrial mammals same wt. - response to greater heat production requirement a. large body large volume/sa ratio - as size, relative amount of SA to Vol is reduced Vol = r 3 SA = r 2 - heat is contained w/in Vol but is exchanged to air/water across SA - larger the animal, less SA per unit Vol of animal (less heat loss) Whales & Pinnipeds tend to be large!! C. Insulation 1. HAIR underfur hair stiff guard hairs o use of oil secretions to repel water o underfur traps air next to skin o need to keep fur clean, groomed, oiled o adaptation to shallow water only fur compressed to ½ / 33 depth 2. BLUBBER very effective whales have lost fur for H 2 O- dynamics pinnipeds rely on a combo of fur & blubber - Bowhead has 20 of blubber - Most seals have 3-4 of blubber D. Migration Behavioral adaptations 1. most large whales feed in arctic- Antarctic waters 2. migrate to tropical regions for birthing 3. blubber used as energy source while in tropics (doesn t yield high heat energy) 3

4 4. calves need warmer water for survival; need time to build fat reserves for colder H 2 O E. Vascular Shunts 1. common in most animals in cold, wet environment a. heat exchange from warm outgoing arterial blood to incoming cold vein b. occurs in extremities feet of ducks & geese legs of moose flippers, fins, flukes of whales & pinnipeds c. outgoing heat returned to body before it s lost in extremities F. Cooling 1. overheating is often a problem 2. vascular dilation of dermal BV 3. walruses turn pink over entire body, most Pinnipeds dissipate heat from flippers wave flippers in air for cooling 4. use of sand for cooling & prevent sunburn! G. Reproduction: 2 Options: 1. Birth in Water (Whales, dolphins) Breathing, swimming, predation problems 2. Birth on Land (Seals, sea lions) Predation, buoyancy problems H. Multiple Mates: Types of Reproduction Monogamy: one male with one female Polygamy: Polygyny one male + several females Polyandry one female + several males 4

5 I. Polygyny in Pinnipeds Very unique social structure & behavior among mammals breed seasonally on offshore islands, remote mainland beaches, ice flows breed only after extended season of dispersed feeding extremely gregarious dense rookeries w/ 100 /100 yds 2 site faithful - return to place of birth go into estrus a few hours a year always just a few hours after birthing delay implanting embryo to uterine lining time synchronous birthing of rookery most gregarious of all mammals (except cave bats) more specialized than other mammalian a. 3x-6x larger than b. large canines c. extremely aggressive toward other and uncooperative d. protective fur & skin on upper body e. some with saggital crest f. N. elephant seal trunk amplifies bellowing territorial mates w/ up to 100 (typically 20-30) a. may sire 80 young/lifetime b. give birth to 3-4 young/lifetime all Otariids and all but 2 genera of Phocids are polygynous J. Reasons for Polygyny 1. heritable attributes of that leaves more offspring = genetic inheritance to future generations (polygyny will replace monogamy over time when possible) 5

6 2. Polygyny only possible if economically efficient a. essential resources are clumped so a can defend resources & s b. ecological circumstances force to congregate in small area at same time so a powerful can defend them 3. Reasons favoring environmental Circumstances a. mothers must haul-out of water to birth b. young are helpless &: can t swim (need land for feeding & development) c. all Pinnipeds are slow & awkward on land vulnerable to terrestrial predators mainland birthing site risky small offshore islands protective Space Limited! - usually few sites available d. near water rookery necessary for cooling e. puppying prefer haul-out sites among dense clustered s than an empty beach 4. These conditions favor economy for s defending large # s - large size & fat reserves allow for starvation period while on rookery II. Marine Mammal Evolution Timeline: 500 mya land animals emerged from aquatic origins 65 mya whale ancestor returned to the sea 30 mya seal/sea lion ancestors returned 5 mya sea otter ancestor returned 6

7 A. Classification of Marine Mammals Kingdom Animalia Phylum Chordata Class Mammalia Order: Carnivora Suborder Pennipedia Family Phocidae Family Otariidae Order Cetacea Superorder Odontoceti Superorder Mysteceti B. Order Carnivora 1. Suborder Pennipedia (seal/sea lions) - Body streamlined, limbs specialized for swimming - 2 proximal limb segments short & partially enclosed in body integument - toes fully webbed (5) 1 st & 5 th of hind usually longer - tail short, eyes large, clavicle absent - lower Miocene (30 mya)to present a. Family Phocidae (hair seals) - Atlantic origin (evolved from mustelid) - hind limbs extend posteriorly & cannot rotate foreward - fur stiff w/out woolly underfur - no external ear pinna - palms & soles hairy - propulsion from hind flippers; steering from pectoral flippers (harbor seal, sea elephant) 7

8 b. Family Otariidae (eared seals) - Pacific origin (evolved from bear-like lineage) - hind foot turned foreward for support - very mobile on land - palms and soles naked - external ear pinna present - testes external (CA & Stellers sea lion, N. fur seal) C. Order Cetacea (2 superorders) 1. General Characterisics - large pelagic marine mammals - body fusiform with no cervical constriction - head large to 1/3 of body length - forelimbs reduced to flattened, no external segmentation - flukes: lateral expansion of skin & dense, fibrous tissue in caudal (tail) area - hindlimbs absent, vestiges of pelvic girdle remain internally - auditory meatus (ear) small opening behind eye, no pinnae (ear flaps) - bones spongy: cavities filled with oil - skeleton is light & flexible 8

9 - eyes small without nictating membrane - use echolocation (sonar best dev.) in all toothed whales & some Baleen valuable when visibility (find food, group members, navigating) dolphins known for great variety of vocalizations sensitivity: dime at 100m & tell if heads or tails (navy dolphins) fin whale mourns heard 500mi baleen whales use clicks (lower freq used to communicate 20 mi or more) 2. Superorder Odontoceti (toothed whales) - homodont teeth (no specializations) present at birth - two nostrils unit (one nasal opening) - manus pentadactyl (1 st & 5 th digits reduced) - predatory on other marine mammals, fish & large invertebrates - evolved in Eocene - highly evolved echolocation - Sperm whale, Orca, Porpoise, Dolphin 3. Superoder Mysticeti (baleen whales) - mostly large (30 to 130 tons) - no functional teeth present - roof of mouth with baleen-ectodermal plates (used for straining food from water) - two external nasal openings - evolved in Oligocene - echolocation not well developed to absent - Gray Whale, Humback 9

10 Specific Examples: PHOCIDAE: HARBOR SEAL Phoca vitulina 1. most common pinniped seen in OR - Habitat: self waters, bays, estuaries, up rivers (Oregon City), some become residents in lakes - Distribution: entire coast from lower CA to AK - Food: (fish & shellfish) rockfish, herring, lamprey, octopus, crustaceans, salmon, my crab bait! - Description: length: 48-67, wt. 300 lbs pelage: white to gray-mottled dusky above large eyes situated high nostrils high on snout - Reproduction: mate summer w/ delayed implantation gestation 9 months (delay implantation of embryo) 1 pup, born May-June pup can swim at birth no organized harem or rookery seeks sandbars for birth pup mortality fairly high (eagle food) - Enemies: killer whales, GW shark, man, eagle - Population: 300,000 NE Pacific Oregon (5,200) Columbia 1,500 Umpqua 800 Coos Bay 1,200 Tillamook 600 Bandon 200 Rogue 300 Netarts 200 Siletz 100 Alsea

11 OTARIIDAE: CALIFORNIA SEA LION Zalophus californianus - Habitat: common winter resident here ( only) - used as circus seal (trains well, sml, mobile) - Range summer: CA to Mexico winter: move N to OR, WA, BC ( don t range this far N) - Food: squid, octopus, herring, rockfish, sculpin - Description: 8 long X 600-1,000 lbs. shorter, lbs. head relatively small adult has saggital crest color: reddish brown to buff, black when wet agile on land (for a pinniped) stubby hind flippers voice: honking bark ( circus seal ) - Enemies: GW shark, some Orca, man - Reproduction: mate in May-August bulls gather harem of 10 gestation 1 year; 1pup/birth & pups stay in southern range - Population: 13,000 living on Channel Islands Oregon 3,500 in early Fall ( ) migrate south in spring to mate STELLAR SEA LION: Eumetapias jubata - Largest of pacific sea lions - Habitat: rocky shores of islands & mainland concentrate in river estuaries & forage up-river (sea lion caves of OR) - Range: channel islands of CA to AK summer migrate N in July to BC/AK & pups remain off coast all yr winter - return south 11

12 - Food: lamprey, squid, sand lance, pollack, flounder, sculpin, cod, herring, shark, skates, perch, minimal halibut & salmon Dive 600 for food! - Description: large: 11 long X 2,200 lbs smaller X 1,000 lbs has massive forequarters, saggital crest pellage: short/coarse, no underfur color: buffy-brown to light when dry - Enemies: orca, GW shark, man - Reproduction: occupy remote rookeries large harems 1/40 ratio combat between bulls often to death gestation 12 months 1 pup; learns to swim in tidepools pup 40lbs at birth, self-sufficient 3 mnths - Population: 300,000 worldwide; 50,000 AK/BC Oregon 3,000 Channel Islands (CA) 1938 (2,000) 1960 (50) NORTHERN FUR SEAL: Callorhinus ursinus Don t come ashore along OR or WA Harvested on Probilof Islands for fur & dog food (65,000/year) - Range: Alutian Islands, Bering Sea, Gulf of AK & young migrate miles offshore to CA & Japan (6,000 mile route) - Description: color: dark brown, silver gray size: bulls 7 long X 600 lbs cows smaller, lbs head small, muzzle short dense underfur (valuable fur) 12

13 use flippers for thermoregulation flippers out of water retain heat fan flippers in air for cooling - Food: squid, non-commercial fish species, (1.5% of diet salmon) Dive to 180 to forage - Reproduction: bulls gather harem of 40 savage battles between s often to death 1/3 body wt lost during mating season (2 mnths) gestation: 1 year, 1 pup/birth pup teaches self to swim mother forages for 1 week/time to 100 mi feeds 1 gallon of rich milk, returns to sea NORTHERN ELEPHANT SEAL: Mirounga angustirostris - Driven to near extinction by whalers & sealers - Habitat: confined to subtropical waters currently - Range: former rookeries Baja to San Fran one small island (Guadalupe Island) off coast of Mexico presently expanding range northward >15,000 live off coast of CA seen at Cape Arago in summer regulary (sighting as far north as Siletz Bay) - Description: size: to 17 X 5,000 lbs, much smaller proboscus of used solely for territorial defense (amplifies snorts that can be heard for great distances: no vocal chords involved) - Reproduction: 1/7 of bulls do most of mating territories defended by snorts & combat harem of 12 cows leave colony temporarily to forage when return, calves drink milk until they look like fur-covered balloons 13

14 high infant mortality due to crushing by large in colony easily the deepest diving mammal known - Deep diving record at 5,000 (2,000 lbs/in 2 ) a. two mile round trip in 40 minutes submergence record >2hrs a. can repeat dive repeatedly within minutes of surfacing (no rest) b. never seem to sleep c. dive continuously 24 hrs/day for 8 months strait! d. 90% of life spent in deep dives e. migration: cows leave island & migrate west of OR, WA & north of Hawaii bulls migrate to Alutian Islands both engage in continuous deep dives all the way abundant food between 1,500-2,400 avoid GW shark & Orca g. known mechanisms for deep dives: blood = 20% of body wt (high Hg) enlarged spleen (serves as scuba tank) high O 2 storage in myoglobin lower MR by 5-6 o F before long dives shunt blood from kidneys & digestive organs drop HR from 120 bpm before dive to :6 bpm on bottom :2 bpm recorded 14

15 Common Cetaceans: CALIFORNIA GRAY WHALE 1. unchanged for 200,000 yrs 2. no dorsal fin, bumps on back 3. short baleen (16 ) 4. is 1/3 larger 5. feed 4 months in arctic, put on 25% body wt (5.6 tons) 6. feed by plowing through mud after amphipods & other invertebrates - most are right headed plowers 7. largest migration (12,000 mile route) 8. migrate to breed & fast (don t eat) 9. nurse 6-8 months (calf gains 2-3 tons, drink 1,300 gallons 53% fat-milk) 10. mom takes year to recover 11. migrate N mid-march, S in Dec-Jan 12. OR has resident whales (due to plentiful resources) Species status: Atlantic Gray Whale extinct 300 yrs Korean Gray Whale extinct, last 1 recorded 1979 CA Gray Whale has recovered Order Carnivora: Sea Otters (Family Mustelidae) - Family with skunks & weasels - Heavily hunted to near extinction for fur: $2500/pelt in late s pelts considered most valuable & rare - Range: once entire coastal length (CA to AK) require kelp beds for food and habitat regulate kelp growth by eating urchins - last 30 yrs, relocated AK otters to OR coast return to home territory (difficult to establish) one male appeared in fall 2009 in Yaquina Bay area 15

16 - Description: 5 long AK population largest weight lbs rear feet webbed, front with fingers hair 1 thick (only thermal insultation) mature at 3yrs/age 8 yrs - Behavior: seldom come ashore sleep wrapped in kelp, floating on back extend all 4 limbs out of water (thermalregulation & vitamin syn) scratching dislodges parasites tool use for cracking shells - Feeding: sea urchins, mollusks, some fish adults consume ¼ body wt/day - Reproduction: rough water stimulation either gender initiates mating birth anytime of yr; 1 pup only pups cared for about 1 yr (carried on stomach by ) has no interest in young 16