Amazing Nature: Mice have longer sperm than elephants
In complete contrast to how one can think the sperm of a mouse is longer than that of an elephant.
Scientists now have an explanation for it. A study published in the Proceedings of the Royal Society of London tells
Researchers from the University of Zurich while studying the sperm science examined the sperm count and size of sperm and tried to find its link with the size of any species.
They found that in smaller species, the length the sperm must travel to reach the egg is reduced, making the sperm more likely to get lost and the size more important.
"The sperm of rodents is at least twice as long as sperm of large mammals like primates, tigers, and even whales. We wanted to know why sperm sizes differ so dramatically when they all have the same task - to fertilize eggs", said lead researcher John Fitzpatrick from Stockholm University, Sweden.
"We show that males invest more in sperm size and number in species where sperm from multiple males compete to fertilize eggs compared to monogamous species," Fitzpatrick explained.
They also found that the size of the female influences whether it is better for a male to produce longer or more sperm.
In larger females, with bigger reproductive tracts, sperm can be lost or diluted on its journey to the egg. Therefore, in larger species males produce a lot of tiny sperm.
In contrast, in small species where sperm have an easier time finding the egg, males produce comparatively longer sperm.
"This demonstrates that the location where sperm compete - inside the female's reproductive tract in mammals - determines when it pays a male to produce longer or more sperm," the researchers said.