Aquatic life Flashcards
What two orders can the Cetacea be divided into?
Mysticeti (baleen whales) and Odontoceti (toothed whales)
What characterises the Mysticeti?
No melon (no echolocation), pairs of blowholes, naris (nasal passage) anterior to the eye (in front of), baleen
What characterises the Odontoceti?
Melon and use echolocation, complex nasal passages, naris posterior to the eye (behind)
What is the evolutionary history of cetaceans?
Most closely related to the terrestrial herbivores Artiodactyla. Transitional forms from terrestrial to aquatic seen in the fossil record
Pinnipedia is the largest group in Carnivora - what are the 3 families that Pinnipeida can be divided into?
Otariidae - eared seals e.g. sea lions, fur seals. Better on land
Phocidae - true seals, no external ears. More adapted for marine life
Odobenidae - single species, the Walrus
What are the key features of cetacean reproduction?
Mate at sea with a deep dive. Testes are abdominal, penis is retractable
What are the methods of thermoregulation in aquatic species living in cold water?
Mass inertia – very large so can conserve heat inside the body
Insulation from blubber and fur
Counter-current heat exchange
What are the key features of cetacean respiration?
Extended apnoea - suspended breathing
Rapid rates of gas exchange
More red blood cells and myoglobin
Lactic acid tolerance
What are the key features of cetacean locomotion?
Fusiform body shape, reduces drag
Larger body mass increases power
Hind limbs absent
How does echolocation work in Odontoceti?
Clicks produced by forcing air through complex nasal vessles. Focused through the ‘melon’
