Activities and videos that introduce to the concept of illusions in nature.
Experiment 1: Click here to find a pdf of hidden animals. Look at the pictures and time how long it takes you to find the hidden animals. Try it again in a couple of weeks and compare your results.
Experiment 2: Do you think age plays a role in how well someone can spot the hidden animals? If so, conduct an experiment. Make a data table to record each person’s age and how long it took them to see each image. Something like the data table below.
Does age appear to be a factor?
This illusion looks at light waves in the ocean. These light waves help explain why some fish have particular coloring to help them “just keep swimming” in the big ‘ol ocean!
Watch the stop-animation video on the website to see how different light waves affect our ability to detect color. Note any differences and changes that are made as each. This demonstration was inspired by the San Francisco Exploratorium.
Did you detect any changes? Let’s discuss these changes you detected. We’re used to seeing the world around us illuminated by light in a full range of colors—and our eyes have evolved accordingly. This combination of light has allowed us to perceive our world around us as colorful and bright.
Remember when we discussed the parts of the eye that help us see in bright light. A typical human eye has three types of cones, or color receptors, each sensitive to mostly reddish, greenish, or bluish light. When all three are stimulated simultaneously (as they are by the three bulbs used here), your visual system perceives “white,” rather than individual colors of light. That is why between the white light and the three colored bulbs there was not much of a change.
But colors seem to play tricks on our perceived vision when we shift the light balance: an orange fish may look green in one light, grey in another. The perceived color of any object you see comes from reflected light.
For example, a red fish appears red because it absorbs all the many colors in white light except red, which it reflects back to your eyes. However, objects can only reflect back the light that’s available. A red object can’t look red if there’s no red light to reflect. Instead, it will simply look black. Did you make that observation? If not, look at the image below and see for yourself what happened when we removed the red light.
Did you notice some fish are harder to detect when there is an absence of red light waves? Turning off the red bulb allows us to get a sense of the effect of diving deep underwater. White light tends to lose its red component as it moves deeper through the water. This then leaves behind mostly blue and green light to illuminate the underwater environment. In this blue-green light, a red fish may look black, and a yellow fish may look green.
So, how do aquatic animals use this illusion in action? Many prey organisms living at depths where blue light penetrates, but red does not, have evolved to be red. To their predators they appear nearly black, effectively disappearing in the dim light of the deep.
DO NOT DO THIS WITHOUT SUPERVISION!
Want to give this a try? Instructions available from the San Francisco Exploratorium can be found by clicking here. The Exploratorium recommends using special light bulbs but we have been successful using flashlights and colored cellophane paper. You can get the cellophane paper from amazon or a party store, if you’re lucky you might even find it at the dollar store. We have seen it done with fabric as well but since cellophane and fabric are flammable make sure you have an adult helping!
If you are able to create a video we would love to see it. Send a YouTube link to email@example.com and we will definitely check it out!
For an extra challenge, try taking your own hidden nature image. Go in your backyard or around your home and see if you can spot any animals using camouflage in nature. This works best if you sit very still for a few minutes. Also, most animals are active in the morning or evening horse when it is not too hot.
If possible, take a picture and email it us at firstname.lastname@example.org and we will try and add it to this website! Add a little description of where the hidden animal(s) are at in the picture. Make sure the photo is only of the animal. If you’d like some recognition, include your first name and the name of the school you attend.