The Weird and Wonderful
World of ….
Animal Eyes
 ANIMAL EYE TYPES
 The main eye components that help us with our
vision and light are: the pupil, the iris, and the
lens
 Animals eyes can be very different from a
human's eyes, as many animals' eyes have
adapted in order to help them see more clearly
and survive in their different environments.
 Many weird and wonderful eye types have
resulted.
CAMOFLAGED EYES

Many animals need to be able to trick their
enemies. One way to avoid being seen is
to make sure their eyes don't stand out
and give them away.
CAMOFLAGED EYE
 Why do animals need
this type of eyes?
Many animals need to be able to trick their
enemies. One way to avoid being seen is
to make sure their eyes don't stand out
and give them away.
Animals with camoflaged eyes (l-r):
Balloonfish, Chameleon, Red eyed tree
frog, Butterfly fish
All of these camouflage adaptations allow
animals to blend into their habitat and can
readily go undetected.
Whether to help them sneak up on prey
without being seen, or to allow them to
escape predators more readily
PSEUDO EYES
Pseudo means to pretend, and pseudo
eyes are eyes that are fake or meant to
trick you.
They certainly look real, but are just clever
colourful markings, which help to deceive
their enemies.
 Animals with pseudo eyes (l-r): Flounder,
Treemoth, Tanzanian caterpillar, Spotted burrfish
 In this way, animals are able to protect and use
their real eyes, whilst their predator thinks they
are looking the other way.
Another trick of the pseudo eye is that it may
also warn off potential predators, as it seems to
make the animal appear more dangerous and
menacing than it really is by its big, scary looking
eyes.
Strange Eyes
 Speaking of scary, some
animal's eyes really are
frightening!
Take for example the
vulture, which looks
positively evil whilst
wiping its eyes with a
milky looking membrane
(which is kind of like an
inner eyelid as it also
serves to keep out bright
light and dust),
 and the vampire-like
praying mantis looks
like something
straight from a horror
film doesn't it?
 Other eye types are just
down right weird looking.
Look closely at the eye of
the conch - not only are
the eyes decorated with a
circular spirals (good
enough to many any
hypnotist jealous) they
also protrude on stalks to
allow the conch to see
from within its shell.
 On the other hand the
female net casting spider
look like her eyes have
been replaced with huge
marbles! These massive
glassy eyes actually
enable her to let in as
much light as possible,
and also provide her with
the best possible type of
vision at night
These types of eyes are so unusual its a
wonder that they work at all!
In actual fact all of these weird and
wonderful eye types are perfectly suited to
the kind of vision each animal needs to
survive in its surroundings.
Strange Pupils
 Not only are there weird looking
eye types within the animal
kingdom, but some animals have
pupils just as strange to match!
 Many animals do not have the
round pupil hole we have as
humans, but rather there is whole
array of shapes and sizes.
Believe it or not, these strange
pupils actually enable the animals
to get the best type of vision from
their environment.
 Pupil shape doesn't have to be
circular - it can be square or
rectangular shaped like the
octopus, or an irregular shape
altogether like the whipsnake
 Whether they need a
large pupil to help the
eyes capture as much
light as possible when in
dark habitats like the cat,
or the ability to narrow the
pupil when in bright light
like the gecko whose slitlike pupil actually shuts
down to two tiny circles
so as to avoid damaging
the eyes.
 It is mainly nocturnal animals
that exhibit strange pupil
shapes. The reason for this
being that the eyes of
nocturnal animal are not
accustomed to bright light, and
therefore need to take extra
care not to damage them when
exposed to light. Their
strangely shaped pupils in
actual fact can react more
quickly to bright light (even if it
is only for a brief momentary
flash of bright light).
Lots of Eyes
 There are even those animals that think 2 eyes
are not enough, and enlist the help of many
pairs of eyes to help them see.
 Ever looked closely at a fly eye? If you have you
will notice lots of little holes - which are actually
hundreds of separate little eyes. This kind of eye
is called a compound eye, and many insects
also have these, as it enables them to receive
many different visual images to inform them of
the space around them.
Spiders are often seen to have a few extra
pairs of eyes to help them see, which is
pretty handy when you're looking out for
predators and prey at the same time.
Scallops and clams are seen to have 1-2
rows of eyes around their shells that
enable them to look in every direction and
allows them to sense movement
scallop
spiders
Animals with many eyes: Fly, Jumping
spider, Wolf spider, Scallop
UNUSUAL EYE POSITION
Sometimes some animals need eyes in
the back of their head - literally! Or to the
side, or on stalks, etc…
Especially animals that are under attack a
lot and need to be constantly on the
lookout from the enemy.
The starfish, conch and snail (along with
many other animals) have eyes at the end
of their tentacles, this provides them with
the ability to poke out a tentacle from
behind a shell or other type of protective
shelter, without putting its whole self in
danger.
Whereas the arrowhead crab has eyes on
either side of its head which allows it to
see all around and directly in front.
The hammerhead shark's eyes are at the
end of large lobes on the head, so the
shark is not able to see straight ahead,
however it has adapted a swimming
motion that enables it swing its head from
side to side in search of prey.
 Animals with unusual
eye position (l-r):
snail, starfish,
arrowhead,
hammerhead shark

 THE NOCTURNAL EYE
 Some animals prefer to be awake and active
during the night-time, and sleep during the day.
These animals are termed nocturnal.
Nocturnal animals have special eyes that help
them to see in the dark, and these eyes are
quite different from the eyes of daytime (diurnal)
animals, or even humans.

 Tarsier, Loris, Fruit
bat, Owl
Nocturnal animals tend to have big eyes
(in proportion to the size of their body) and
pupils that open far wider in low light
conditions than those of diurnal daytime
animals. Therefore nocturnal eyes gather
more light than other eye types do. What
may appear as pitch black to a human
may look like dim light to a nocturnal
animal.
When its dark, or there's very little light, its
almost impossible to see colours clearly.
However it is much easier to tell the
difference between black and white isn't it?
 It is for this reason that nocturnal animals have evolved
an eye that has given up its ability to see colour, and in
exchange has gained super effecient vision in the dark.
For example, did you know that an owl can't see in
colour - but can see a mouse moving over 150 feet away
with light no brighter than a candle. Pretty amazing
really!
 Therefore nocturnal animals need to have extremely
light-sensitive eyes, and as such have to be extra
cautious of day light and bright light conditions, as it can
severely damage their eyes, or even blind them.
 How do they protect their eyes?
 The same way daytime animals and even us
humans do - by restricting the amount of light
entering the eye via the pupil.
 1) Pupil Flap
Some animals have a special 'eye-flap' that can
be pulled over the eye to protect it (like a
sunshade).
Basically the flap is able to drawn over the pupil
when light levels become too intense.
Additionally it may serve to act as extra
camoflage when necessary.
Pupilflap
Cuddlefish
 2) Pupil Constriction
Most nocturnal animals however rely on the
speedy contraction of their pupils to limit the
amount of light entering the eye.
 A slit pupil, with two sides that can close like a
sliding door, is far better at this task, which is
why so many nocturnal eyes have slit pupils.
These pupils can be vertical (cat), horizontal
(octopus) or diagonal (whip snake).
Common nocturnal animal pupil shapes