Did you know? Tens of millions of animals accomplish thousands of miles of continent and ocean crossings with precision yearly. Arctic terns round-trip between polar hemispheres. Sea turtles come back to their birth beach to breed. Gray whales travel between ocean basins.
How do animals ever manage such incredible migrations without maps, compasses, or GPS? Scientists found that nature had provided such creatures with cutting-edge biological navigation mechanisms, some of which we’re only now cracking.
These biological navigation mechanisms utilized everything from the Earth’s magnetic field to the position of the stars, one of the great mysteries of biology.
Earth’s Magnetic Field: The Internal Compass
Some other creatures possess magnetoreception, a sensitivity to the Earth’s magnetic field. Not science fiction, but a proven biological fact behind much animal migration.
Sea turtles are the most famous magnetic navigators. Loggerhead turtles hatch on Florida beaches, scramble to the sea, then take an ocean detour of 9,000 miles for several years.
Research conducted with Dr. Kenneth Lohmann at the University of North Carolina demonstrated that turtles possess an internal magnetic map that guides them outward during their initial migration. The adult females utilize the map years later to find the birth beach, usually a few hundred yards away.
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Magnetic field navigation: In the Spotlight
- Magnetite crystals in animal brains serve as miniature compass needles
- Photoreceptor proteins in birds’ eyes “read” magnetic fields
- Whales use the magnetic contours of the sea floor as underwater freeways
Scientists estimate the sense is so precise that other animals can detect differences in magnetic intensity that would require sophisticated equipment to detect in humans.
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Celestial Navigation: Reading the Sky
Birds make great astronomers. Migrating birds employ the sun during the daytime and stellar constellations at night to provide internal compass directions during extended flights.
Juvenile indigo buntings, North American songbirds, learn star patterns from migrating in a darkened sky with the North Star (Polaris) in the center. Planetarium star field experiments, which manipulated the researchers’ suggestions, indicated that birds utilized novel star information to recalibrate their internal compasses.
Example: Bar-tailed godwits also hold the record for the longest one-way flight, covering 7,000 miles from New Zealand to Alaska in just 8 days. Solar navigation and internal circadian clocks aid in adjusting the direction of flight as the angle of the sun changes throughout the day.
Whales also possess star navigation ability. Humpback whales that migrate during the night were discovered to be able to make swimming direction corrections in a manner appropriate for star navigation. The multi-sensory systems, excluding magnetic field navigation, have redundancy in case one is lost, as it is compensated for by others.
Olfactory Maps and Infrasound
Some animals employ navigation systems. Salmon employ olfactory imprinting, imprinting the distinctive chemical scent of their natal stream and tracking odor gradients upstream years afterward, generally hundreds of miles inland from the ocean.
Whales and elephants are fed infrasound—ultra-low frequency vibrations in the wave form of sound that propagate hundreds of miles over sea and land. These have been suggested to guide them around obstacles crudely and communicate over hundreds of miles.
Pigeons integrate magnetic sense with vision and even olfactory sensation. Pigeons create two-dimensional mental maps using composite senses based on their surroundings. Redundancy in the mechanism renders their orientation near foolproof.
You’ve heard it. Animals migrate, and this is how they’re able to do it: by detecting the magnetic field, the location of the stars, the chemical odor, and sound waves we can hardly detect. They’re not low-level reflexes of a sort; multileveled high-tech orienting equipment developed over millennia.
Sea turtles, birds, and whales bankrupt our GPS technology with biological accuracy. So the next time you see geese migrating in the sky or read in the news about a whale migration, just take a moment to think, you’re witnessing one of nature’s engineering wonders.
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