Marine Mammals Flashcards
What are the 3 marine mammalian orders?
- Cetartiodactyla
- Sirenia
- Carnivora (+ pinnipeds)
What are systematics?
Reconstruction of phylogeny (evolutionary history)
What are the 5 families in the carnivora order?
Pinnipeds: - phocidae (earless seals) - octariidae (sea lions + fur seals) Others: - Mustelidae (weasels) - Ursidae (bears) - Odobenidae (walruses)
What are the 2 sub orders of the Cetacea?
odontoceti - toothed whales
mysticeti - baleen wales
Name 5 challenges of living in water
- Inability to change lung gasses at all times
- Increased heat loss
- Resistance to movement
- Changed sound propagation
- Low light levels
What is uni-hemispheric sleep and which sub orders of marine mammals exhibit it?
Where one hemisphere of the brain “sleeps” with the contra-lateral eye remaining open
Happens in odontocetes, orariids and odobenidae (no evidence for mysticetes)
Name 5 characteristics of cetaceans
- Large fusiform bodies
- Modified pectoral skeleton with no pelvis or hind legs
- Oil filled bones and elongated skull
- Nostrils positioned dorsally & dorsal fin/ridge
- Blubber
How do baleen wales feed?
Using baleen plates
What is the difference between balaenids (right wales) and balaenopterids (roquals)?
right wales: - Large and bulky with arched mouth - Long baleen hairs with fine hairs - No dorsal fin, slow swimmers roquals: - Long and slender, little arch - Short baleen plates with course hairs - Dorsal fin, fast swimmers
How do toothed wales and baleen wales differ in blow holes?
toothed wales have one, baleen have 2
Which whales are deep divers? What other features do they exhibit?
Sperm whales: - Asymmetric skull - Small under slung jaw - spermaceti organ in head Beaked whales: - pronounced beak - 1/2 pairs of teeth - pair of throat grooves
What adaptations do delphinids have for hunting?
- Large falcate dorsal fin foro high speed swimming
- Conical teeth from prominent beak
- Echolocation
Which toothed whale family is found exclusively in the arctic?
Monodontids
- Bulbous heads filled with melon
- Flexible necks
How do propoises differ from delphinids?
No beak, triangular dorsal fin, flattened spade-shaped teeth
Name 3 adaptations of sirenians
- Large fusiform body
- Nostrils on top of muzzle
- Dense heavy bones and thick skin counteract blubber buoyancy
What adaptations are necessary for pinnipeds to survive on land?
- Ability to support body weight
2. Sound production and hearing that works in air
Name 3 characteristics of pinnipeds
- Fusiform flexible body
- Dense blubber/fur for insulation
- Modified appendicular skeleton with hindlimbs for propulsion and forelimbs for locomotion on land
Name 3 characteristics of otariids
- Ability to rotate pelvis for walking on land
- Small external ears
- Rely more on fur for insulation
How are phocids different?
- Unable to rotate pelvis
- No external ears
- Use blubber and fur for insulation
Can odobenids rotate their pelvis?
no
Name 4 characteristics of sea otters
- Dense under fur
- Flattened hind feet
- Horizontally flattened tail
- Small ears
What is blubber and what other functions can it have apart from insulation?
Adipose tissue thickened by collagen and elastic fibres
Can improve hydro-elastic shape, store elastic energy and act as an energy resevoir
How is dense fur achieved?
Long guard hairs provide protection and short guard hair trap air underneath
How do marine mammals avoid overheating?
furry - divert blood flow to flippers
blubbery - divert blood flow to dorsal fit, flippers or dilation of blood vessels outside blubber
What 3 ways can marine mammals enhance oxygen stores?
- Increase lung capacity
- Blood volume + storage capacity
- Muscle volume + storage capacity (myoglobin)
How do cetaceans avoid gas pressures and N2?
- Do not allow N2 into the blood
- Terminal airways reinforced with cartilage and muscle
Why are marine mammal lenses stronger?
Focussing power of air/cornea interface is lost in water
How is sound produced by marine mammals?
Generated in the nasal system and transmitted + focused by the melon
How is sound received in marine mammals?
Via a fatty lobe at the side of the head and fatty core in the jaw bone
