THE SEAL’S SENSES
The path of light in the eye
Incoming light first stimulates the receptors on the retina.
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Sensitive whiskers
Vibrissae, also called whiskers, are highly sensitive sensory hairs
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Seeing underwater
Seals dive with their eyes open and see clearly underwater to identify fellow seals, obstacles, and prey. A thick, tough leather-like skin protects them from high water pressure. The lens is round, adapted for underwater vision.
Seals can also see very well in dark water. This is due to the size of their eyes and a higher number of rods in the retina, which are responsible for night vision. In addition, they have a tapetum lucidum – a reflective layer in the eye that acts like a residual light amplifier.
AHA!
Have you ever wondered why the eyes of some animals glow in the dark?
Many nocturnal animals have a tapetum lucidum that reflects incoming light – especially visible when you shine a light at them.
The path of light in the eye
Incoming light first stimulates the receptors on the retina. Then it is reflected back by the tapetum lucidum and hits the retina again, stimulating the receptors a second time.
Sensitive whiskers
Vibrissae, also called whiskers, are highly sensitive sensory hairs located on the seal’s snout and above the eyes. They detect even the slightest water movements left by prey or objects.
Based on these flow patterns, seals can determine the size, shape, and direction of an object. Experiments show they can follow these traces using only their whiskers – without relying on vision or hearing.
AHA!
Why do harbour seals sometimes have dark rings under their eyes on land?
This happens when their tears overflow and wet the fur around the eyes.
Vibrissae are more complex than normal hair. When a vibrissa moves, muscles and nerves beneath the skin are activated and send impulses to the brain.
Seals use their vibrissae to sense water vortices that a fish leaves behind – so they can track it even in dark water.
AHA!
Did you know that seals can hear very well underwater?
However, they only use their sense of smell on land – to recognize fellow seals.