User:Katydid484/sandbox

Migration Methods

 * Turtle navigational skills for migrations are still unknown. There are several hypotheses including astronomical cues and the Earth’s magnetic fields. Although unknown, there is scientific evidence that the sea turtles do have a navigational compass when making long migrations.


 * The astronomical cue hypothesis for sea turtle migration one without scientific evidence. These cues would include light from the sun, moon, and stars . If the sea turtles used astronomical cues, they would not be able to navigate in waters where light does not attenuate well, on cloudy days or when the moon is blocked by clouds . The moon is not a good astronomical cue because there is a new moon every 28 days. With narrowing out the astronomical hypothesis, the use of earth’s magnetic fields can be viewed as the navigational tool for long-migration patterns of sea turtles.


 * Earth’s magnetic fields are used for migration for a wide variety of species including bacteria, mollusks, arthropods, mammals, birds, reptiles, and amphibians . In order to understand the Earth’s magnetic fields, the earth can be viewed as a large magnet. As a typical magnet has a north and south end, so does the earth. The north pole magnet is located at the Earth’s north pole and the south pole magnet is located at the Earth’s south pole. From this north and south pole span magnetic fields. The magnetic field leaves the poles and curves around the earth until it reaches the opposite pole.


 * In regards to the magnetic field hypothesis, there are three main concepts that should be considered. The concepts include electromagnetic induction, magnetic field chemical reactions, and magnetite. In regards to electromagnetic induction, it is assumed that the sea turtles have electroreceptors. Although evidence has been found in other species such as rays and sharks, no evidence has shown that there are electroreceptors in sea turtles making this hypothesis invalid. A second concept from the experimentation by Irwin involves chemical reactions which is commonly found  in a variety of species of newts and birds. The strength of the magnetic field affects the chemical reactions within the bodies of the newts and birds. The final concept includes the magnetic crystals that form during the magnetic pulses from the earth’s magnetic fields. These magnetic crystals formed by magnetite give the turtles directional information and guides in migration. The magnetite affects the cells of the nervous system of the sea turtle by producing a signal that references the forces of the magnetic field and the direction and magnitude that is applied . If this magnetite is used in the migration, when the earth’s magnetic poles reverse at the dipole moment, they signal that the sea turtle nervous system receives will change the migration direction . Regardless of the hypothesis, hatchling turtles have the ability to determine the direction and inclination angle of which they are swimming with aide from magnetic fields