Anatomy and Physiology of Whales

By. Sara Kowalski

Toothed Whales vs. Baleen WhalesToothed Whales (Odontoceti)

Baleen Whales (Mysticeti)

• Toothed whales are predators that use their teeth to catch their prey

• Baleen whales have a sieve-like structure called baleen that catches huge amounts of tiny krill

Anatomy of Baleen Whales

• In general, baleen whales weigh about 1 ton for each foot of length

• Females are generally larger than males• All Baleen Whales have two blowholes• All toothed whales have a single blowhole

Anatomy of Baleen Whales Cont.

Skeletal System

In all whales, the ribs are bound to the spine by flexible cartilage, which allows the ribcage bend and adapt to higher pressures when diving.

The neck is made of compacted vertebrae to stiffen neck when diving and swimming fast

The front flippers have a shortened humerus to stiffen into a paddle, they have extra phalanges, but only four sets to form into a flipper for steering

Some whales have a vestigial pelvis — a remnant from four-legged land ancestor Numerous vertebra behind pelvis, giving a lot of flexible movement for up/down

powering of fluke Chevron bones for muscle attachment

Fluke starts where chevron bones stop

Whale Digestion System

Many whales have three stomachs, although some whales, like the sperm whale, only have two

The three stomachs:The first stomach (forestomach) mechanically crushes the

foodThe second stomach is where chemical breakdown begins The third stomach is the pyloric stomach and secrets

gastric juices

Circulatory SystemWarm bloodedHas a large amount of red blood

cells Increases amount of oxygen carried

The heart of a whale can make up about 2% of its body weight

The heartbeat of a whale varies from whale to whale

In general, larger animals have a slower heat rate than smaller animals

Average heart rate of large whales are about 10 to 30 heart beats per minute underwater

Whales slow their heart rate when they dive, conserving oxygen and allowing them dive longer

Thermoregulation Baleen whales maintain a body temperature between about 36.6°C and 37.2°C (98-99 °F)

There is a heat gradient throughout the blubber to the skin A blubber layer just underneath the skin is made of fat cells and fibrous connective tissue

Blubber makes up 27% of a blue whale's body weight 23% of a fin whale 36% to 45% of a right whale

The blubber layer can reach up to a thickness of 20 in. on a bowhead whale Thick layer of blubber results in a streamlined body, making it energy-efficient for swimming

Blubber is an energy reserve Reduced limb size decrease the amount of surface area exposed to the external

environment This helps conserve body heat

A baleen whale's circulatory system adjusts to conserve or dissipate body heat and maintain body temperature

When a baleen whale dives, blood is shunted away from the surface. This decrease in circulation conserves body heat

Muscular SystemAll whales have muscles with a high level of

MyoglobinThis is a red pigment similar to hemoglobin that stores

oxygen in the muscles for use during deep divesMuscles prominently control the tail and the flukes

Tail provides forward motionFlukes are used for steering

Senses SIGHT:

vision is not extremely important to them except when they're at or near the surface HEARING AND ECHOLOCATION:

Dolphins and toothed whales have excellent hearing and use echolocation to sense objects

Baleen whales don't use sophisticated echolocation, probably because they don't have to stalk prey

SMELL: Have a very limited or non-existent sense of smell The olfactory bulb in the brain is primary for sense of smell, but these olfactory bulbs

are reduced in baleen whales and are absent in toothed TASTE:

Research on the existence whales' taste buds is mixed and contradictory Experiments have shown that dolphins do have a sense of taste

TOUCH: Skin is very sensitive to touch

MAGNETISM: Whales may use the magnetic field of the Earth for navigation purposes on their long

migrations across the oceans It is not known how they sense magnetism

Resourceshttp://www.enchantedlearning.com/subjects/whal

es/anatomy/

http://science.howstuffworks.com/zoology/marine-life/baleen-whale1.htm

http://www.seaworld.org/animal-info/info-books/baleen/physical-characteristics.htm

http://oceantoday.noaa.gov/whaleanatomy/