Sense Light (Non-visible Spectrum) From the Environment
Living systems interact with each other and with their environments to gain information. Sometimes that information is in the electromagnetic spectrum. Wavelengths in the electromagnetic spectrum are also called the non-visible spectrum, because humans can’t detect them with the naked eye. These include ultraviolet (UV) light, infrared (IR) light, radio waves, and other wavelengths. Detecting within these spectra requires strategies beyond those used for visible light, so many living systems that depend on these signals have specialized organs to do so. For example, beetles that feed on burned trees have sensory organs that detect infrared radiation emitted by fires, enabling them to quickly locate a burned area.
Send Light Signals in the Non-visible Spectrum
Living systems interact with each other and with their environments to gain information, which is sometimes in the electromagnetic spectrum. Wavelengths of the electromagnetic spectrum are also called the non-visible light spectrum because humans cannot detect them with the naked eye. These include ultraviolet (UV) light, infrared (IR) light, radio waves, and other wavelengths, which living systems can use to send signals. Those signals must not only be targeted to other living systems that can detect them, they must be energy- and material-efficient. This creates both challenges and opportunities. For example, some web-weaving spiders add UV-reflective silk strands to their webs to keep birds and bumblebees (which can see UV light) from crashing into and destroying them. But because the insects the spiders feed on they can’t see UV wavelengths, they fly into the web.
Protect From Animals
Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.
