Spermaceti organ

[1] In the modern sperm whale (Physeter macrocephalus), this organ is far larger in proportion to the animal's body than what would be explained by simple allometry.

Its evolution has caused changes in basal skull morphology, which may implicate that a trade-off was made that compromised the functionality of other features.

[4] The hypertrophied quality of the sperm whale's nose can be interpreted as an adaptation for deep diving unique to Physeteroidea.

[5] Two main hypotheses exist for use of the spermaceti organ: The first has been challenged by many authors, with the following points raised as problematic: the change in density that could be achieved by manipulation of spermaceti oil temperature would likely have a negligible impact on the animal's overall buoyancy; the anatomical features that would be needed for heat exchange with the spermaceti organ don't appear to be present; a mechanism of temperature regulation would necessitate high physical exertion while at great depth, which deep-diving animals tend to avoid; sperm whales appear to be highly active during dives, countering the suggestion that buoyancy manipulation would be advantageous because of its benefit in remaining motionless while diving; and the evolution of the spermaceti organ with buoyancy as a selective pressure would be very difficult and is unlikely due to the fact that the organ wouldn't have any impact on buoyancy until it became extremely large in proportion to the body.

Under this hypothesis, it assists in echolocation for foraging during deep dives, allowing the whale to manipulate the sound waves' direction and power to more easily detect prey.