Back to whales

A few posts back I referred readers to a very interesting New Yorker article about the history of American whaling.

Reading about sperm whales made me realise I had a knowledge gap: why are they called that? The New Yorker review also mentioned spermaceti as being a whaling product, and I didn't know what that was. (Ambergris I knew about: it was featured in an Uncle Scrooge comic I read as a child.)

So Wikipedia to the rescue. Spermaceti is:

... a wax present in the head cavities of the Sperm Whale (Physeter macrocephalus) and in the blubber of all whales. Spermaceti is extracted from whale oil by crystallisation at 6 °C, when treated by pressure and a chemical solution of caustic alkali. Spermaceti forms brilliant white crystals that are hard but oily to the touch, and are devoid of taste or smell, making it very useful as an ingredient in cosmetics, leatherworking and lubricants.

As for why sperm whales have it in their head, this is rather interesting:

One function of the spermaceti organs is a buoyancy or diving organ. Before diving, cold water is brought through the organ and the wax is solidified . The increase in specific density generates a down force (approx 40 kg equiv) and allows the whale effortless sinking. During the chase in deep levels (max 3km!) the stored oxygen is consumed and excess heat melts the spermaceti. Now only hydrodynamic forces (by swimming) keep the whale down before effortlessly surfacing.

Knowledge gap filled.