How sperm whales ram without breaking their skulls? A ploy for female attention
Why do sperm whales have such large heads? A study found that they use them ramming devices to gain female attention. Why don't they get injured then? The sperm whale's head contains a sac that prevents fractures.
Why do sperm whales have large heads?
Sperm whales have huge, bulbous heads, and scientists have been intrigued for a long time about their purpose. Several reports suggest that the whales used their heads to ram ships and other sperm whales. According to records, the idea that their foreheads were used as battering rams cropped up after two whalers said the sea giants sank two whaling ships, the Essex in 1821 and the Ann Alexander in 1851.
Sperm whales sank ships with their large heads
However, it remained merely a theory for the longest time. It wasn't until 2016 that scientists actually started believing in the "ramming" idea. It was believed to be used not just for sinking ships, but also to attract potential mates.
Sperm whales ram into male rivals with their heads for mating purposes
Another theory behind the large heads is that the sperm whales use them to smash into their rivals while competing for female attention. An incident on the lines of mating was recorded in the Gulf of California in 1997. This further pushed the theory that males hit each other with their heads to win over a mate.
So why do female sperm whales also have large heads?
However, this theory had its flaws. If the males were competing with other males for mating, then why did the female sperm whales also have such large heads? Panagiotopoulou's team found that the forehead served multiple functions besides the ramming. It is important in echolocation, communication and buoyancy control, she said.
Why don't sperm whales fracture skulls when they ram their heads?
Olga Panagiotopoulou of the University of Queensland, told BBC, that the sperm whales' head has a huge, fluid-filled chamber called the junk sac. It has the potential to absorb energy from forceful impacts, preventing the skull from getting fractured.
Scientific reasoning behind large sperm whale heads
The connective tissue partitions are absent which increases skull stresses, particularly in the rostral aspect of the upper jaw, the study authors wrote. This further hints at the importance of the architecture of the junk in ramming events. The study also found that impact loads on the spermaceti organ generate lower skull stresses than an impact on the junk.
Main purpose is using it as a massive battering ram against males
While the researchers agree that the huge head and the unique structure of the junk serve multiple functions, they note that its primary function was to serve as a massive battering ram during male-male competition.
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