Swimming, Diving & Echolocation 1

Swimming & Diving

Swimming, Diving & Echolocation 2

Swimming

• Most representatives have streamlined bodieso Notable exceptions are the polar bear and sea

otter• Pinnipeds swim using mainly their flippers

o Some sea lions can swim up to 22 MPH• Cetaceans and sirenians swim using flukes in a

vertical fashion

Swimming, Diving & Echolocation 3

Swimming

• To avoid inhaling water all marine mammals take quick breathso Fin whales can

empty and refill its lungs in less than 2 seconds

o This is ½ the time we take

• Cetaceans have the advantage of having a blowhole on top of the heado This allows them to

breathe with most of the body remaining in the water

Swimming, Diving & Echolocation 4

Diving Physiology

• Marine mammals have mastered the art of diving, this allows them to exploit food at considerable depths

Sea otters – 4 to 5 min. up to 180 ft. Northern elephant seal – capable of depths of 5,000 ft. Weddell seal – 1 hr & 13 min. and 1,900 ft. Baleen whales do not dive deep and seldom dive deeper

than 300 ft. Toothed whales are excellent divers

• Dolphins can dive 990 ft• Sperm whales can dive for over an hour at 7,400 ft

Swimming, Diving & Echolocation 5

Diving Physiology

• Have more blood than non-diving mammals with a higher concentration of hemoglobin

• Muscles are extra rich in myoglobin which allows for more oxygen to be stored

Swimming, Diving & Echolocation 6

The Dive Reflex

• Heart rate slows dramaticallyo Bradycardia

• Blood flow to non-essential body parts is reduced allowing blood to be used where it is needed most

• Vasoconstriction offsets dramatic drop in blood pressure

• Water pressure collapses a flexible rib cage forcing air out of the lungs

Swimming, Diving & Echolocation 7

Echolocation

• Marine mammals depend very little on smell, but do have good vision

• Most have a sensory system based on hearingo All toothed whales, some pinnipeds and baleen

whales

• Echolocation is natures version of sonar

Echolocation

Swimming, Diving & Echolocation 9

Nice Melon!

• Melon - fatty structure found on the head o Focuses and directs

sound waves

• Sound is received by hollow oil/fat filled lower jawo Sound passes to two

very sensitive inner ears