Whales navigate with incredible accuracy underwater using Earth's magnetic fields.
“Whales use the Earth’s magnetic fields to accomplish feats of astonishingly accurate underwater navigation as they travel the oceans of the world.” (Shuker 2001:50)
Image: NOAA Photo Library / Flickr / Some rights reserved
Sense Electricity/Magnetism From the Environment
Some living systems use electric or magnetic signals as a way to receive information from their environment. Magnetic and electric fields can help such living systems determine direction, altitude, or location, and electric fields also help living systems find other living systems. Detecting and interpreting electrical and magnetic signals requires specialized techniques. For example, mud-dwelling bacteria use crystals composed of magnetite to sense geomagnetism, which helps orient the bacteria to burrow deeper into the mud.
Navigate Through Liquid
Living systems that move in liquids must navigate around physical obstacles and find their way from place to place to locate resources or suitable climates. Many liquids are denser than air, which means it’s a thicker medium through which signals must pass. On the other hand, liquids tend to conduct some signals better than air or solids. Liquid dwellers must use strategies that enable them to detect and follow signals in this dense medium. For example, electricity transmits well in water and several organisms, such as Amazon electric eels, have organs that detect and use electric signals to navigate.
Mammals
Class Mammalia (“breast”): Bats, cats, whales, horses, humans
Mammals make up less than 1% of all animals on earth, but they include some of the most well-known species. We know first-hand some of the characteristics that make mammals unique, like having hair, being able to sweat, and producing milk through mammary glands. Another critical shared feature is a set of highly-specialized teeth. Unlike sharks or alligators, for example, whose teeth are generally all the same size and shape, mammals have differently shaped teeth in different areas of the jaws to target specific foods or foraging strategies.
