Page 68 - One Million Things: Animal Life - The Incredible Visual Guide

Wolf spider eyes are arranged
in rows and allow for effective VISION
night-time hunting

For many animals, vision is their most important sense.
They use it to create an image of their surroundings so that
they can navigate, find food and mates, avoid predators,
and communicate with each other. Animals can see because
they have light receptors, usually housed inside special
sense organs called eyes. These receptors turn light into
nerve signals, which are then turned back into images by
the brain. Quality of vision varies greatly between different
species. Flatworms can distinguish only between light and
SPIDER EYES dark, while some mammal eyes generate 3-D color images.
All spiders have eight simple eyes, but many depend more
on their sense of touch to detect and trap their prey. However,
active hunters, such as jumping spiders and this wolf spider,
use large, forward-facing eyes to locate and catch prey.

CEPHALOPOD EYES FORWARD-FACING EYES
Octopuses and other cephalopod mollusks have highly Forward-facing eyes enable hunters, like this eagle, to judge
developed eyes. They allow their owners to find and catch distances accurately so they can pounce on moving prey.
prey, and to navigate away from predators. Unlike other Tree-dwelling primates, such as monkeys, also have forward-facing
cephalopods, cuttlefish have unusual W-shaped pupils. eyes, which allow them to jump safely from branch to branch.

EYESPOTS NIGHT VISION
The most simple eyes are eyespots. In water-dwelling Like many nocturnal animals, red-eyed tree frogs have large eyes
flatworms, cup-shaped eyespots act as simple light in relation to their overall body size that are efficient at capturing
detectors, enabling the flatworm to shy away from bright light in dim conditions. In the tropical forests of South America,
light and move to darker, safer areas under rocks or plants. they use their keen night vision to ambush moths, flies, and crickets.

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