Sun's position will be combined with the time of the day to find the correct direction.
Examiner News report added, "Monarch butterflies have an internal body clock that is genetically programmed to tell the butterfly what time of day it is". Finally, the mystery has been solved by scientists from the University of MA and the University of Washington.
"Their compass integrates two pieces of information - the time of day and the sun's position on the horizon - to find the southerly direction", said Eli Shlizerman, a University of Washington assistant professor.
The butterfly needs this info to find its direction during its annual migratory trip.
To understand how this navigation system works within the monarch brain, a team led by Eli Shlizerman took their knowledge of monarch physiology and neurology, and they emulated it in a model circuit.
3-D visualization of the Monarch butterfly's brain with neuropils related to sun compass integration highlighted.
Monarch butterfly uses its eyes to monitor the sun's location. Sun's position in the sky. The second step is to match that up with the time of day in order to figure out which direction is southwest - something the monarch does with its antennae. Fortunately, like most animals, including us, monarchs have an internal clock based on the rhythmic expression of key genes. This "clock" is located in the antennae, and it sends this valuable information via neurons to the brain.
Scientists said the internal Sun compass consists of two control mechanisms. This was gleaned as he and a group of biologists recorded these cues from the butterflies' antenna and eye neurons.
"We created a model that incorporated this information - how the antennae and eyes send this information to the brain". The crux of the matter lies in how its brain processes the information and then decides how to migrate in a southwestern direction.
In the researchers' model, two neural mechanisms - one excitatory and one inhibitory - controlled signals from the antennae's clock genes. Their model had a similar system in place to discern the sun's position based on signals from the eyes.
According to Arizona State University: "There are four stages in the life cycle of a butterfly".
The model also indicated that the same mechanisms are reversed when the insects need to make their way back to the northeast in the spring. Shlizerman said their goal was to make a robotic monarch butterfly that could follow the insects to track their complete migration. These brain networks keep the monarch butterflies from swerving off course in the journeys they make each year. "The researchers found that the butterflies have an internal mechanism that inhibits or excites the direction keeping clock depending on whether the path of flight is obstructed by an object or the butterfly is blown off course". The control centers in the brain were studied in depth. So far, aspects of their model, such as the separation point, seem consistent with observed behaviors.
The time of day is the missing link here.
Using the new model, if a monarch gets lost or off track during their migration due to wind, they turn whichever direction that doesn't require crossing the separation point.