“But we still don’t know why they are called sperm whales!”
Yeah, well, to find the answer, we have to look on their anatomy, especially the head.
Even for Cetaceans, sperm whales have a weird head. The skull is excavated by a huge basin where sits the biggest nose of the animal kingdom.
The massive head of a sperm whale. Note the blowhole on the left side.
The explanation for this strange shape is complex and related to sound production. The sperm whales, like all the toothed whales, are using sound for hunting and localize preys, what we call echolocation. These sequences of high pitch sounds, or clicks, are very specific in sperm whales because of the tissues situated in their head. It is composed of several distinct layers.
The first one is a thick layer of tendons and muscles. Really hard to cut by the way. The layer is only localized on the upper part of the head and permits an accurate adjustment of the shape of the head.
All these red “ropes” are tendons. An alternance of tendons and muscles and as you can see, it is quite thick.
The second layer is a big yellowish organ, the spermaceti. So, here we are, the explanation for the name sperm whale. Why is it called like that? Just guess.
The liquid contained in the spermaceti organ. “It looks like candles or… oh wait! That’s gross!”
The liquid contained in the spermaceti is funny. Its consistency is changing depending the temperature. So on the picture up there, it is solid because it’s cold. But at the moment we opened the whale, because of the fermentation, the body was still hot, and it was all liquid.
When we tried to cut through, the liquid was under pressure. Cutting a hole through the tendons layer, one of the guys could see it and took a nice shower of sperm…aceti, then told us “now you know why it is called a sperm whale!” In fact, it is not sperm, it’s some lipidic substance used to amplify sound. But, people first thought it was really sperm they were storing in their nose. Think about it next time you blow your own nose.
Because of its funny consistency, the spermaceti has been precious during the industrial revolution. It was used to oil the mechanisms, make candles, soap...
That’s why whaling have been so popular and even influenced some artists (Moby Dick, Pinocchio for example).
Until recently, the spermaceti was used for lipsticks. Beuark.
The spermaceti organ is very important in echolocation, it’s a good sound conductor. The sound is produced by the phonic lips, an organ situated under the blowhole at the tip of the head. The sound is reflected by a nasal air sac, go back through all the spermaceti and is reflected by a last bubble layer on the skull. It passes through the junk organ and is finally emitted (see the picture below, which is clearer). Complicated, uh? Even scientists are not sure about how it’s working, so don’t worry about that. To sum up, the spermaceti organ is actually working like some kind of acoustic amplifier.
(A) What phonic lips look like. Unfortunately, you can only see one of these, the second one was a bit too damaged; (B) the “bubble layer” reflecting the sound on the back of the skull (from Martin Abrahamson); (C) a drawing showing how sperm whales produce clicks (© Museum of New Zealand Te Papa Tongarewa, 2007). Monkey lips and phonic lips are the same organ.
Other alternative hypothesis have been proposed to explain the complex head of a sperm whale like buoyancy, headbutts fights or even judging the male quality (by the kind of sounds is producing). Which one is the good one? Maybe one of these, maybe a combination of those. Seems that we still know almost nothing about these fat guys that continue to surprise and amaze us.
