L7 - Marine Mammals 2 Flashcards
1
Q
Why do photoreceptors in marine mammals vary?
A
The photoreceptors of marine mammals are tuned to the depths at which the dive
2
Q
Describe how marine mammal eyes are specialised
A
- lens tends to be spherical
- Pinnipeds have extensive pupillary contraction forming a vey thin slit/pinhole
3
Q
How much faster does sound travel in water compared to air?
A
4.5x’s faster in water
4
Q
What is the distance that a sound travels in water dependent on?
A
Frequency
- high frequency = attenuate over short distances
- low frequency = travel furthest
5
Q
How do dolphins produce sound?
A
By implosive movements of air in nasal passages, but the mechanism is unknown.
The sound is produced while the blowhole is closed and projected forwards.
The melon possibly focuses the sound
6
Q
How is sound received in dolphins?
A
- Echo’s are picked up by all body parts
- Ear channels are reduced and blocked with wax
- Inner ear is isolated from the rest of the skull by a cushion of bubbly foam
- Fat channels in the jaw transmit sound straight to the ossicles
