Whales

• Evolved from land mammals 50 to 65 million years ago

• Evolved from ungulates(related to horse and sheep)

Temperature Regulation• Blubber (also for buoyancy and energy storage)

• Counter-current blood flow – warms blood as it returns tocore of body• Muscles generate heat• Low surface area to volumeratio - little surface in contactwith water to lose heat

Oxygen• blowhole (nostrils) on head – easier• Empty and fill lungs quickly (2 seconds for a fin

whale)• Large lungs• High gas exchange rate (absorb 90% of oxygen

- humans absorb 20%)

Oxygen• Many red blood cells, hemoglobin – carries

oxygen• myoglobin - carries additional oxygen• Shunt blood from non-vital organs (stomach,

kidney) when diving to vital organs (brain, heart, muscles)

• Slow heartbeat rate when diving

Propulsion Through the Water

• Streamlined• Internalized body parts - ear, penis, mammary

glands – reduces friction• Shorter appendages – forelimbs for steering• Loss of hind limbs• Loss of hair

Propulsion Through the Water• fluke (tail) for propulsion

– Up and down (unlike fish = side to side)– ↑ surface area– Also to identify individuals - like fingerprint

• flippers – for steering and balance

Sensing the Environment• Good eyesight – but little to no light• echolocation - biological SONAR – find and

maybe to stun prey• Very good hearing - sound travels faster in

water than in air• ex: humpback songs for communication –

social, territorial

Pressure

• Collapsible lungs• Nostrils close to prevent water from entering• Do not get the bends

– when we dive if ascend too quickly, dissolved nitrogen forms bubbles – pain, embolism, death

• Tissues and blubber have higher affinity for nitrogen

Types of Whales• Toothed whales – suborder Odontoceti• Baleen whales – suborder Mysticeti

Types of Whales – Toothed Whales• Have teeth – to catch prey, not chew• Eat mostly fish and squid - killer whales eat seals• Dive deeper• Most do not migrate• Ex: sperm, pilot, killer whales, dolphins,

porpoises• Ex: sperm whales dive > 3,500 feet for giant squid,

up to 75 minutes

Types of Whales – Baleen Whales• No teeth - 600 - 800 baleen plates to filter krill

and other items• ex: blue whale eats 4 tons of krill per day• Not deep divers• ex: humpback - lung feeding (lunge forward,

pleats open), flick feeding (flick tail), bubble feeding (blow bubble net and swim up)

Types of Whales – Baleen Whales• pleats – folds under mouth

– open like accordion when feeding

Types of Whales – Baleen Whales• ex: humpback - lunge feeding (lunge forward,

pleats open), flick feeding (flick tail), bubble feeding (blow bubble net and swim up)

Types of Whales – Baleen Whales• ex: blue, humpback, right, gray, fin• North to feed, south to breed - behavioral

adaptation– north - summer for krill– south - winter to raise young

• ex: gray whales, 3 monthmigration, Arctic to Baja, CA,6,000 mi one way

Reproduction• coincides with migrations• internal fertilization• live young born• nurse and grow quickly, ex: blue whale, 130 gal milk/day, grows 200 lbs./day• low birth rate• pods – family groups of whales - social

Whale Behavior

• Breaching – jumping out of water– to remove parasites, social behavior, stun prey?

• Spyhopping – sticking head out of water– curiosity, look for prey, communication?

Whale Behavior• Beaching – swimming up onto beach• Can be one or many individuals• Cannot hold up body on land• Reasons – noise pollution, disease, injured,

red tide, anomalies in magnetic field, lost?

Whaling• Hunted by indigenous people• Problems starting in 1600s – industrial whaling

– not for food– blubber – oil for lamps and soap– baleen – anything we use plastic for today –

combs, umbrellas

Whaling• Low reproductive rates – one young every 2 to

3 years• Could not withstand whaling pressure• Better technology made things worse - factory

ships, harpoons

Whaling

• International Whaling Commission (IWC) group of countries to regulate whaling industry

• Marine Mammal Protection Act – 1972 – U.S. law – bans hunting and harassment of all marine mammals