Scientists have finally found out a bit more about the sperm whale's potential ramming capabilities. It turns out that this whale's head is, in fact, built to ram other whales when competing for females.
In the past, a 19th century whaler suggested that the forehead of male sperm whales partially evolved to be used as a battering ram. However, this theory was never fully investigated until this study.
"The sperm whale forehead is one of the strangest structures in the animal kingdom," said Olga Panagiotopoulou of the University of Queensland, lead author of the new paper. "Internally the forehead is composed of two large oil-filled sacs, stacked one on top of the other, known as the spermaceti organ and the junk sacs. It is the oil within the upper spermaceti organ that was the main target of the whaling industry in the early 19th century. This whole complex is highly sexually dimorphic which means that it is much larger in males than in females, a pattern commonly found in species in which males fight to compete for females."
In this latest study, the researchers created a computer model to simulate ramming in sperm whales. When analyzing bridges, tunnels or buildings, the researchers are given exact measurements and material properties for the simulations. In this case, though, the researchers had to work with limited data.
"Increased skull stresses at a ramming event can be detrimental for the animal since they can cause fatal fractures," Panagiotopoulou said. "Our findings show that the mechanical advantage of the structure of the junk may be the result of acquired traits related to the selection on male to male aggressive behavior. Although male sperm whales may not fight frequently, we know that aggressive ramming behavior is a common characteristic in the group of mammals from which whales are derived-the even-toed ungulates, the artiodactyls. A closer look into the anatomy of the heads of other species of whales that ram may reveal a variety of protective mechanisms."
The findings reveal a bit more about this whale. More specifically, they show that connective tissue partitions embed in the junk absorb impact stresses that protect this skull. This, in turn, shows that sperm whales may actually ram one another and evolved to do so.
The findings are published in the April 2016 journal PeerJ.
