TUESDAY, Sept. 10, 2002 (HealthDayNews) -- When it comes to love, male sperm whales are real buttheads, says a study by University of Utah biologists.
They found male sperm whales go head-to-head when they're fighting for the affections of female whales, and that aggressive behavior may explain why some sperm whales ram ships.
The researchers say the classic book Moby Dick was inspired by the ramming and sinking of a ship by a large sperm whale in 1820. They add such behavior is no fluke.
"We believe that this ability to sink ships is the result of whales evolving so that males could butt heads to compete for females," says study co-author David Carrier, an associate professor of biology.
The whales' tale appeared in a recent issue of the Journal of Experimental Biology.
"We were trying to find out how sperm whales are able to hit ships so much bigger than them and swim away. Humans can't run into things that much bigger than us, and come away unfazed. We make a fairly strong argument that the body of a sperm whale is designed to withstand severe impacts unharmed. It's evolutionarily advantageous to their survival," says study co-author and biology student Jason Otterstrom.
The first part of their study looked at male-female size differences of 21 cetacean species such as whales, dolphins and porpoises, and the size of each species' forehead.
They found foreheads are largest in species where males are much bigger than females. That includes sperm whales.
They note a sperm whale's forehead accounts for a third of the whale's body length, and comprises 25 percent to 30 percent of the whale's weight.
"If the forehead was the battering ram used for male-male aggression, then you would expect it would be relatively larger in those species in which males are larger than females," Carrier says.
He and his colleagues also used computer simulations of male sperm whales going noggin-to-noggin to determine if the forehead acts as both battering ram and shock absorber. Sperm whale foreheads contain chambers filled with oil that they use to focus sound for sonar and communication.
Some marine mammal experts are skeptical, and say sperm whales wouldn't risk this important sound organ by butting heads with other whales.
The University of Utah researchers acknowledge their study was limited by a lack of time and money to directly measure the forehead sizes of the different cetacean species. They had to rely on information from a field guide.
More information
Here's more on the history and habits of sperm whales.
