Sperm whales are the only whales known to rest vertically, floating steadily just below the ocean’s surface. Scientists have hypothesized that the whales release air bubbles to help them stay neutrally buoyant but the mechanism for how they do so has not previously been demonstrated — until now. “We already knew that sperm whales rest in a stereotypical vertical position and that they had been observed releasing bubbles during these resting periods,” lead author of a new study Noémie Freymond, a researcher at the Université de Neuchâtel in Switzerland, told Mongabay by email. “It had been hypothesized that the release of bubbles was related to buoyancy regulation, but this had not been demonstrated experimentally or systematically recorded.” Sperm whales (Physeter macrocephalus) are buoyant largely thanks to a massive oil-filled organ, called the spermaceti organ, located in their heads. Waxy spermaceti oil is lighter than water, making the whales buoyant. It was once used as a fuel for lamps and candles and the reason the whales were targeted by hunters.  The whales’ lungs, respiratory tract and spermaceti organ are all low-density organs positioned near the head and help the whales stay vertical. As the whales drift up, lower pressure allows air in the lungs to expand, pushing the whales toward the surface. Releasing bubbles counteracts that upwards push and allows the whales to stay submerged instead of bobbing to the surface. The study’s research team used data from 42 sperm whales that had been tagged with suction cups near Norway’s Lofoten…This article was originally published on Mongabay

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