Sea turtles have long wondered how they determine the direction of the ocean. There are several theories, including the use of visual cues and imprinting of the magnetic field of the Earth. Some believe that they follow waves, while others suggest that they follow a magnetic compass. In any case, the answer is a complicated one. Read on to learn more about this fascinating animal and its amazing life cycle.
Sea turtles sense Earth’s magnetic field
Scientists have demonstrated that loggerhead sea turtles use their magnetic sense to locate their natal beaches. Because each part of the coast has its own magnetic signature, the animal can remember and use it as its internal compass. However, the exact mechanism by which this phenomenon works remains unclear. Here are some possible explanations for this phenomenon. And how can we learn more about it? Let’s explore the theory in more detail.
A study published in Nature Communications in 2010 has found that sea turtles sense the Earth’s magnetic field as a navigational cue. The intensity and inclination of this magnetic field varies over Earth’s surface. These magnetic signatures are unique to oceanic regions. The researchers arranged experiments in which hatchlings were exposed to the magnetic fields of two different locations: the Pacific and Atlantic Ocean. They also placed the hatchlings in circular water filled arenas and tethered them to an electronic tracking unit.
They imprint on their shells
Turtles imprint characteristics of their natal beach on their shells. These imprinting characteristics may include smell, low-frequency sound, magnetic fields, and seasonal offshore currents. When young turtles first head out to sea, they may follow older, experienced females who have already made the trip to the sea. As they learn about their new home, they may imprint the unique characteristics of the beach on their shells.
This ability to imprint on one place is unique among non-avian creatures. Female loggerhead sea turtles, for instance, imprint on the magnetic field signature of a particular beach in order to navigate back to the beach to lay their eggs. And juvenile sockeye salmon also seem to use magnetic fields to navigate back to their beach homes to lay eggs. So what makes a seashell so unique?
They follow waves or visual cues
Turtles follow a variety of visual and kinetic cues to determine their home. The horizon of the ocean is much brighter than the land and is more reflective, making it easier for hatchlings to recognize the direction they want to go. These visual cues may help the turtles determine where to go once they are ready to migrate to the ocean. They may even use a magnetic cue, or the direction of the sea waves, to make their journey easier.
People also follow waves to get to the ocean. Waves come from different parts of the ocean and are generated from many different directions. When they reach the shore, they tend to travel parallel to the coastline. This is due to a process called wave refraction. If a wave front is approaching from an angle, the shallower part of the wave will be slowed down, while the waves in deeper water will continue to travel at normal speed.
They follow a magnetic compass
Sharks use Earth’s magnetic field to navigate their way in the ocean. Just like birds, sharks feel differences in the magnetic fields and know when to change their direction. Compass needles work because the Earth’s magnetic field shifts the needle northward, which is helpful for humans and other marine animals. Scientists at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science tracked larvae’s movements using a magnetic compass called MagLab.
Originally, ships used magnetic compasses to navigate, but the concept has changed very little since that time. During the Victorian era, British scientists began the Magnetic Crusade to study the Earth’s magnetic field and how it relates to ships and navigation. They found that true and magnetic north align in Greenwich, England. Today, ships use GPS to navigate and sophisticated satellites to measure their position in relation to Earth’s magnetic field.