Did your mum ever tell you to eat lots of carrots because they would help you to see better in the dark? Whilst carrots and other orange and yellow fruits and vegetables will help to prevent certain eye ailments, to see really well at night you actually need special eyes.
Like other nocturnal animals, Quentin the Quoll was able to find food and evade prey even on the darkest of nights. In fact before the disappearance of dinosaurs, most land mammals were nocturnal since dinosaurs were their main predators. Today there is more of a balance but animals such as owls, possums, gliders, many frogs, bats, wombats, koalas, phascogales, many wallabies and geckoes are but a few of the Australian animals that still use the cover of night to survive.
So how do nocturnal animals see so well in the dark?
Of course there are variations in eye features across different animals but scientists have discovered some common characteristics. The most obvious one is eye and pupil size. Some animals like owls, frogs and geckos have eyes that take up a much larger percentage of their skull compared with diurnal (daytime active) animals. Their large eyes and pupils give them large lenses and therefore bigger retinas so that they maximise the amount of ambient light they collect. However, larger eyes means reduced space for each eye to move within the skull, so these nocturnal animals have developed the ability to rotate their necks way past their shoulders to compensate.
As well as eye size, nocturnal animals have retinas which are filled with rods, the eye cells which detect low light levels. They often have few or no cones which are the eye cells responsible for detecting bright light and colour. Again this helps to maximise the amount of light being collected but as a result, nocturnal animals are thought to have little colour vision and things probably look blurry.
Consequently, nocturnal animals also rely on their senses of smell and hearing.
One final common characteristic in nocturnal eyes is a thick, reflective membrane directly beneath the retina. This membrane, called the tapetum lucidum, collects and resends light back to the retina a second time, giving the rods another chance to absorb the image information. This also explains why some nocturnal animals’ eyes seem to glow in the dark when a light is shined on them. Cats too have nocturnal glow in the dark eyes, which explains why they are such a threat to wildlife at night.
The purpose of this blog is two fold. Firstly, it is hoped that this information will support the delivery of the Australian Curriculum: Science. It is most directly linked to the Year 5 Science Understandings (Biological sciences — Living things have structural features and adaptations that help them to survive in their environment) and Science as a Human Endeavour (Use and influence — scientific knowledge is used to inform personal and community decisions). However, it is also a real life example of the Year 5 Science Understandings (Physical sciences — Light from a source forms shadows and can be absorbed, reflected and refracted) and will provide teacher background information for Science Understandings in Year 1(Earth and space sciences — Observable changes occur in the sky and landscape) and Year 3 (Biological sciences — Living things can be grouped on the basis of observable features…)
The second purpose is to make you aware of a new Queensland Museum digital resource called Squawks in the night. It is a slide show designed specifically for Early Years learners, with simple text that relates directly to the photos and a few animal calls. The resource is located on the Queensland Museum website via the following link.
We welcome any feedback or requests for particular topic discussions/resources. Please contact QM teachers 07 3842 9835.
2 thoughts on “But I eat lots of carrots!”
love the quentin the quoll ,must be the eyes
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