Salmon and sea turtles are two species of animals that are known for their ability to return to their birthplace to spawn. This ability is known as natal homing, and it is a remarkable feat of navigation.

How do these animals find their way back to the place where they were born? Scientists have long been puzzled by this question, and there are many different theories.

One theory is that salmon and sea turtles use the Earth's magnetic field to navigate. The Earth's magnetic field is a complex system of invisible lines of force that extend from the North Pole to the South Pole. These lines of force can be detected by animals that have a special magnetic sense.

Another theory is that salmon and sea turtles use landmarks to navigate. They may remember certain features of the landscape, such as mountains, rivers, or coastlines, and use these features to find their way back to their birthplace.

Still another theory is that salmon and sea turtles use the sun to navigate. They may use the sun's position in the sky to determine their latitude and longitude, and then use this information to find their way back to their birthplace.

No matter which theory is correct, the ability of salmon and sea turtles to return to their birthplace is a remarkable feat of navigation. It is a testament to the amazing abilities of these animals, and it is a mystery that scientists are still working to understand.

New theory

A new theory for how salmon and sea turtles find their birthplace was recently published in the journal Current Biology. This theory suggests that these animals use a combination of magnetic cues and water currents to navigate.

The theory is based on the observation that salmon and sea turtles have a special organ called a magnetosome. Magnetosomes are tiny crystals that contain iron oxide, and they are thought to be responsible for these animals' magnetic sense.

According to the new theory, salmon and sea turtles use their magnetosomes to sense the Earth's magnetic field. They then use this information to align themselves with water currents that will carry them towards their birthplace.

This theory is still in its early stages, but it is a promising explanation for how salmon and sea turtles are able to find their way back to the place where they were born.