My 5-year-old and I made a shoebox aquarium (see photo) during the holidays. She has been learning about the natural environment at school and decided to get creative. She made fish and an octopus and a shark, and decorated them all with googly eyes, smiley faces and glitter sparkles. She drew eyelashes on the fish, which made them look super-cute, but it got my 9-year-old thinking:
Do fish actually have eyelashes? What about eyelids? And do they need to blink or does living in water mean that they can always keep their eyes open?
Like lots of other animals, fish usually have two eyes on their head near their nares (holes a bit like nostrils, that help them to smell things) and their mouth.
Fish use their eyes to sense light in their surroundings. Their eyes have special cells (called rods and cones, because of their shapes), which help them to see. Humans and other animals have these types of cells in their eyes too. Rods are used for seeing in the dark or in low light; cones are used for seeing in brighter light and for seeing colours.
Unlike us, fish don’t have eyelids to cover their eyes. But some of them do protect their eyes by covering them with a soft, thin skin-like film (called a membrane), or by making special pigments (coloured chemicals) in their eyes that act a bit like sunglasses.
Fish don’t have eyelashes, either. Eyelashes are made of hair, so they are special to mammals (like humans). They are attached to our eyelids and help to stop dust and dirt from getting in our eyes. A few kinds of birds have feathers that act a bit like eyelashes, and one kind of snake has special scales that do the same job.
Wikipedia has a detailed description of how fish eyes work. And if you’d like to know more about the outside body parts of a fish, check out this video!
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