Marine Reptiles, Birds, and Mammals

Marine Reptiles, Birds, and Mammals

Chapter 9BChapter 9B

Biology of Marine Mammals• Little is actually known about many

marine mammals– Difficult or impossible to keep in captivity– Difficult to observe for long periods of time at

sea• Some whales and dolphins are rarely

seen• What little we know comes from captive

or stranded individuals

Swimming and Diving

• Streamlined-hydrodynamic • Pre-Dive: hold their breath for 15-30s,

then rapidly exhale and take a new breath

• Up to 90% of the oxygen contained in the lungs is exchanged during each breath – Only 20% in humans

• Better at absorbing and storing oxygen• More blood than non-diving mammals

Swimming and Diving

• Higher concentration of red blood cells, and thus more hemoglobin

• Muscles are extra in myoglobin• Heart rate slows while diving• Blood flow to non-essential parts of

the body is reduced• Lungs collapse-prevent the bends• Flexible rib cage which gets pushed

in

Swimming and Diving

• Seals, Sea Lions, & Other Pinnipeds– Swim by moving their flippers

• Sea Lions: 35kph 22mph

– Pinnipeds will jump out of the water to take a breath (when swimming fast)

– Prolonged dives to great depths• Sea Otters: 4-5min, 55m• Pinnipeds: up to 30min, 150-250m

– Slow heart rate• Northern Elephant Seal: 85

beats/min12bpm

Swimming and DivingSwimming and Diving

• Sirenians & Cetaceans– Move tail/fluke up and down

• Blue and Killer Whales: 50kph31mph• Common dolphins: 64kph40mph (Cause

they’re cool)

– Blowhole• Spout/blow- warm breath condensing,

combined with mucus and seawater – Used to identify the whale

– Blubber– Toothed whales= Master divers!

• Sperm Whale (Champ): 2,250m

Echolocation

• Excellent vision… But echolocation is way cooler– Based on hearing

• Finding prey, orient to surroundings• Toothed whales, dolphins and porpoises,

and some pinnipeds (maybe baleen) • Emit sound waves, listen for the echoes • Echoes are analyzed by the brain• Time it takes=how far away object is

Echolocation

• High frequency clicks-– High penetrating power– Can travel long distances– Used to obtain info about the

surroundings

• Low frequency clicks- – Stunning prey?– Discriminate detail– Locate nearby prey

Echolocation

• Air is forced through air passages-closed blowhole

• Frequency-contracting/relaxing muscles along air passages/sacs

• Melon-focuses/directs outgoing sound waves

• Spermaceti organ-larger, buoyancy? Absorb nitrogen?

• http://www.youtube.com/watch?v=EFu_ef9XypY

Behavior

• Highly social – Pinnipeds live in colonies for breeding– Cetaceans live in organized pods

• Sounds/vocalizations– Different from sounds used for

echolocation– Social and sexual signaling– Grunts, barks, squeaks, chirps, “moos”– Sounds moods– Whistles signature

• Dialects• http://www.youtube.com/watch?v=Lk3ZxmptZy

8

Behavior

• Sounds/Vocalizations– Maintain distance between individuals– Breeding, feeding, alarms, birth– Humpback whale songs- serenading

• Communicate with body language• Play behavior- fun fun fun!• Breaching- get rid of parasite, warning,

viewing surroundings• No one left behind• Teamwork!• http://www.youtube.com/watch?v=WabT1

L-nN-E

Behavior

• Dolphins and humans• Stranding/beaching

– Refuse to move/can’t be moved– Internal organs collapse– Pilot and sperm whales– Submarine sonar

Migration

• Pinnipeds and cetaceans– Feeding grounds breeding grounds

• Most toothed whales don’t migrate• Baleen whales

– feed during summer – In the productive waters of the polar

regions– Diatoms and krill– Migrate to warmer waters to breed in

winter

• Gray whale- Longest migration!

Migration

• It’s difficult for scientists to fully understand cetacean migration

• How do they navigate?• Scientists use..

– Small radio transmitters• Satellite

Reproduction

• Pinnipeds– Breed on land/ice– Seals

• Male only breeds with one female• Males ‘rumble’, quiver necks, make bubble

shows

– Sea Lions, fur seals, elephant seals• Male breeds with many females• “Breeding territories”

– Harems (up to 50 females)– ‘Burned out’ – Bachelor groups

Reproduction

• Pinnipeds– Give birth on shore– Close relationship with pup

• Must recognize pup’s call and smell• Pups can not swim at birth • Nursed for 4days-2months

– Female can become pregnant only after ovulation (occurs soon after birth of her pup)

– Gestation-less than a year– Delayed implantation

• Only visits breeding ground once a year

Reproduction

• Cetaceans– Great whales- sexual maturity @ 5-

10yrs– Sexes are segregated within the pod

• Males perform courtship displays

– Gray Whales- third party help..– Gestation lasts for 11-12 months in

most • Relatively short• Sperm Whale: 16 months• Synchronized with migration to warm

waters

Reproduction

• Cetaceans– Calves are born tail first

• Stay connected to placenta- no oxygen depravation

– Calf swims/helped to the surface– Fat-Rich milk rapid growth– Born without blubber

• Must gain weight before migrating with mom to polar feeding grounds

– Close relationship between mom and calf • Return to mommy in times of danger/stress