Humpback whales cover a long distance in migration,which puzzles some scientists. How do they navigate themselves?The passage lists three possible reasons accounting for this phenomenon. But the professor doesnt think that these thing are connected.
First, whales complex brain may give them high intelligence to use stars to navigate by.Their brains are more developed than other animals, for which they are able to recognize stars for orientations.But,other birds like ducks which is not highly intelligent as we know can navigate themselves. silly as they are, their instinct plays a very important role.So,there is no connection between their high intelligence and navigation ability.
Second,moving in straight lines indicates that they can use external objects or forces to figure out where they are.There is no physical landscapes in the ocean but stars which can been seen everywhere.However, the professor doesnt think so.There is a bio-magnetite in their brains,with which they can feel the change of Earth magnetic field.This sensitive organ doesnt rely on external forces or objects.
Third, spy-hopping is an unusual behaviour observed by scientists,which is explained by looking at the stars.Though this behaviour is rare among marine animals, it is ridiculous.Sharks also do this behaviour but they never migrate.Also,whales look upwards in the day without stars in the sky.So, this explanation is pure speculation.