Anatomy and Physiology of Whales

1. Anatomy and Physiology of Whales By. Sara Kowalski

2. Toothed Whales vs. Baleen Whales Toothed 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

3. 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

4. Anatomy of Baleen Whales Cont.

5. 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

6. 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 food • The second stomach is where chemical breakdown begins • The third stomach is the pyloric stomach and secrets gastric juices

7. Circulatory System • Warm blooded • Has 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

8. 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

9. Muscular System • All whales have muscles with a high level of Myoglobin • This is a red pigment similar to hemoglobin that stores oxygen in the muscles for use during deep dives • Muscles prominently control the tail and the flukes • Tail provides forward motion • Flukes are used for steering

10. 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

11. Resources • http://www.enchantedlearning.com/subjects/whales/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/