Whale breaching is a remarkable natural spectacle where a whale propels itself partially or entirely out of the water. This powerful behavior evokes both awe and curiosity, demonstrating the immense strength of these marine mammals. Understanding this phenomenon involves examining the physical act and the various hypotheses for why whales engage in such an energetic display.
Understanding Breaching
Breaching describes the act of a whale propelling its body upwards, breaking the water’s surface, and often rotating before re-entering with a significant splash. To achieve this, whales gain speed by swimming rapidly underwater before sharply angling upwards. They utilize powerful tail strokes to generate the immense force needed to overcome water resistance and gravity. A humpback whale, for example, weighing around 40 tons, must reach speeds of approximately 17-18 miles per hour (28-29 km/h) to fully clear the water.
When breaching, a whale emerges from the water at an angle. A “full breach” occurs when more than half of the whale’s body clears the surface, while a “half breach” involves less. The whale may spin or perform a non-spinning breach, landing on its side, back, or belly. The impact upon re-entry creates a large splash that can be seen and heard from a considerable distance, highlighting the power exerted.
Breaching is energetically expensive, requiring a substantial burst of muscle power, particularly from the tail flukes. A single full breach can demand as much muscle power as 25 draft horses working together. Despite the high energy cost, breaching is often performed in a series. While larger whales like blue whales can breach, their immense size places limits on how often or how high they can perform this act, with average breaches estimated to be between 12-30 feet high.
The Reasons Behind Breaching
The precise reasons why whales breach are not fully known, and scientists propose several theories, suggesting it serves multiple purposes. One hypothesis is that breaching functions as a form of communication. The loud sound generated by the whale’s re-entry into the water can travel long distances underwater, signaling a whale’s presence, conveying messages to other pod members, or serving as a warning of threats. This sound is effective in rough seas where other acoustic signals might be masked by ambient noise.
Another reason is the removal of parasites and dead skin. The forceful impact of the whale’s body against the water during a breach could dislodge barnacles, whale lice, and other external organisms that attach to their skin. These ectoparasites can increase drag, and their removal helps whales maintain their hydrodynamics and overall health.
Breaching may also be a form of play or social interaction, particularly among younger whales. Calves are observed breaching more frequently than adults, suggesting it contributes to developing muscle strength and coordination. For adult whales, it might be a display of strength and vitality, playing a role in courtship or establishing dominance within a group.
Other theories include using breaching to scan the environment above water, although this is less common than “spyhopping” where whales vertically position themselves to look around. Some suggest breaching could also be a method to stun or disorient prey before feeding. Breaching is a complex behavior driven by a combination of these factors.