Function of the spermaceti organ

Question

What is the use of the spermaceti organ of the sperm whale?

One possible theory considered is that it was used for floating and going underwater by heating/cooling the oil. However, it is a lot easier for this to be done mechanically.

Another possibility is that it is comparable to a helmet to safeguard it when it collides with another whale. However, other animals have much simpler structures to deal with this problem.

A third possibility is that it uses it to stun its prey like squid. However, research in inconclusive on whether squids can hear or not. The link below, says that it is probable that squids can only hear upto 500 Hz which is not the frequency used by whales, thus this theory is probably false as well.

https://www.treehugger.com/natural-sciences/what-can-squid-hear-and-why-does-it-matter.html

Answer 1

The principal function of spermaceti and the associated structures in a sperm whale head, is echolocation. The composition of spermaceti suggests that it functions as an acoustical transducer, helping to focus the powerful sound waves used for echolocation. These sound waves likely do not actually stun squids, but they do help sperm whales to find and pursue squids in deep, dark waters.

An echolocation click is formed at the tip of sperm whale's nose, where it is directed backwards, through the spermaceti, toward the sperm whales brain. It then is reflected off an air sac on the sperm whale skull, and redirected forward through a series of lenses before it moves into the water. Check out an illustration of this in the Møhl et al 2003 paper: https://pdfs.semanticscholar.org/88d4/271e9f7490c1173234a2445cf8ddf92fd51f.pdf

The complicated anatomy in a sperm whale's head seems to be directly evolved for echolocation.

Sources: Karol, R., Litchfield, C., Caldwell, D.K. et al. Mar. Biol. (1978) 47: 115. https://doi.org/10.1007/BF00395632

Møhl, B., Wahlberg, M., Madsen, P. T., Heerfordt, A., & Lund, A. (2003). The monopulsed nature of sperm whale clicks. The Journal of the Acoustical Society of America, 114(2), 1143-1154.