Marine Reptiles, Birds, and Mammals Chapter 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, m –Slow heart rate Northern Elephant Seal: 85 beats/min  12bpm

Swimming and Diving Sirenians & Cetaceans –Move tail/fluke up and down Blue and Killer Whales: 50kph  31mph Common dolphins: 64kph  40mph (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? 9XypYhttp:// 9XypY

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

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! Ehttp:// 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 5-10yrs –Sexes are segregated within the pod Males perform courtship displays –Gray Whales- third party help.. –Gestation lasts for 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