Whales use their lower jawbone to the middle ear. whereby they can ear clearly while they are in the water. Human ears and dolphins ears they work the same . They receive sound directly from the air.
In similar way dolphins and human ears are placed in basic anatomical location which is same as on the head. Without a medium hearing is not possible.
The medium sound for human is air. Sound travels 343 meters per second in air and 147 meters per second in water. The most effective way of transmitting sound waves is through water.
We can say that the sound will be fast to travel in medium if the molecules are closer.
Answer:
No one can see in total darkness. Fortunately, there’s almost always some light available. Even if it’s only dim starlight, that’s enough for your eyes to detect. What’s truly amazing is how little light is required for you to see.
Human eyes have two main features that help us see better in low light: the pupil’s ability to change size, and the eye’s two types of light-sensing cells.
Opening up to let in more light
Your pupils are the black areas at the front of your eyes that let light enter. They look black because the light that reaches them is absorbed inside the eyeball. It’s then converted by your brain into your perceptions of the world.
You’ve probably noticed that pupils can change size in response to light. Outside on a bright sunny day, your pupils become very small. This lets less light into the eye since there’s plenty available
They're called anastomoses
