Marine Biology

Marine Mammals

i . Temperature Maintenance

Ø Large size - less loss of body heat (reduces surface to volume ratio)

Ø Insulating layers of blubber or fat

Ø Adaptations of the circulatory system for reducing heat loss

ii. Respiratory modifications for diving

Ø Have the ability to hold their breath for extended periods of time making deep dives possible.

Ø They are able to dive with their lungs empty avoiding problems of buoyancy and bends (nitrogen bubbles in the blood)

Ø Their blood is rich in haemoglobin and other respiratory pigments, and the muscles are rich in myoglobin (another respiratory pigment in the muscles).

Ø During deep dives, sphincters in arteries shut off blood to parts of the body so it only goes where it

Ø Is needed.

Ø The heart slows, and the muscles can tolerate a greater  oxygen debt than terrestrial animals.

Ø When the animal surfaces and breathes, a very rapid O₂-CO₂ exchange occurs.

iii. Osmotic Adaptations

Ø The kidneys reabsorb water and they excrete a very concentrated urine

Ø Fatty insulating layers may also play a role in water storage.

Ø Most water intake comes from the fish they eat.

Oceanic nekton also have adaptations for locomotion, surface resistance, defense (cryptic coloration), sensory systems (echolocation). Some have osmotic adaptations to allow for absorption of fresh water