Now you know why we call them sperm whales – Part 2 –

“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.

Now you know why we call them sperm whales – Part 1 -

The two specimens of Sperm whale stranded in  Henne Strand near Esbjerg

On Monday the 17th of February, I’ve been lucky enough to be part of the autopsy of two sperm whales stranded in Henne Strand (west of Jutland, Denmark). The two animals were found on Saturday, one dead and the other barely alive died in the night of Sunday. We don’t know if these animals were part of the same group.

 It took 3 days prepare the skeletons for the transportation until Copenhagen where they will be entirely cleaned. Although, the stranding of one individual happens from time to time in Denmark, it is rare to see more than one of these monsters on the beach. The last time was in 1997 in Rømø where a group of 16 sperm whales stranded on the beach. 

The reasons are not known yet and will maybe never be known. The two specimens were young males and looked healthy (the first one was full of squids beaks, not really starved). Maybe they approached too much from the coast and could not get back because of the current. I find this hypothesis odd because the animals were not younglings or old adults. 

 The cause of these strandings is still unclear. But once the animals are on the beach, because of their weight, they are unable to move and the compressed organs cause irremediable injuries and slowly kill them. They also can die by drowning: If they are on the left side, the one with the blowhole, they can’t remove the blowhole from the water. 

 In any case, the participation to the dissection and the cleaning was quite an experience. I had no idea of how people were managing such beasts. Well, it’s a lot of messy work, and it takes a long time, but it was really interesting to see the whole anatomy of these animals. Especially when you work on bones, you miss the entire picture sometimes. 

 The first step consists to puncture the beast. After death, bacteria are developing into the bowels and produce heat and gas. A lot of heat and gas. So much gas that it can actually explodes. This is why the puncture step is dangerous but necessary. One guy has to open the animal and release some of the gas to prevent it to explode while the team is working (which would be a bit annoying). With the difference of pressure, the intestines are pushed outside and can be projected at high speed. Yes, it is really dangerous. 

 Puncture of the first sperm whale. The pressure help to cut in the blubber layer which is pretty thick.

 Once it’s done, we had to remove the blubber layer. This is thick and extremely hard to cut. That’s why, we asked for the help of trucks to pull it out. The idea is to progressively strip it off from the rest of the carcass. We began with the tail, which is a bit easier but also because we wanted to see some details at the level of the head that we kept for later on. 

 Removal of the blubber layer. The hardest part is to cut through it, but with the help of trucks and sharp knives, stripping it off is fast. 

 After that, the messy stuff began: we had to remove all the flesh and the organs. The eyes were kept for aging accurately the animals, and the larynx was separated from the rest of the body for study. Different samples were taken on the animal: blood, tissue samples, spermaceti (I will talk about that on another article), stomachal content… All of these will permit to analyze the cause of death of the animal, but also maybe better understand these mysteries of Nature. 

 What a mess… I’m the guy with the fancy cap (the French touch even in the rib cage of a sperm whale) 

 Once the sampling is over and the flesh removed, the skeleton is separated in several parts: the head, the chest, and the tail in two parts at least. It’s facilitating the transportation, but also for the maceration part which will be easier (try to find an entire tank for a complete skeleton, meh). The rest of the preparation will be finished in Copenhagen (removal of the latest rests of meat and assemblage of the skeleton if necessary. But I imagine they will store it for scientific purposes). 

 And that’s it for the cleaning of a sperm whale. Now you know how to do it if one of these is stranded near your home. Just one advice: use only sharp knives. It’s getting blunt so fast when you work on these… you gonna take more time to sharpen it than butchering the animal, trust me. 

 In the next part of the article, I gonna talk about the head of the animal, the structures we observed but also a bit about the dentition. The most interesting part in my opinion.