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Whale penis extrusion & mating practices explained thanks to underwater footage of humpback whale’s penis

During a tranquil lunch on the ocean, following our morning transect surveys, our research team witnessed an unexpected event in the midst of observing a nearby group of humpback whales. The team realized that the whales were headed toward them and decided to put their camera in the water to document the behavior. What they filmed was beyond their expectations – a humpback whale was swimming with its penis extruded, a rare and fascinating sight.

How long is a whale’s penis?

A humpback whale’s penis can be up to 10 feet long and is normally concealed inside the animal’s genital slit. Seeing the whale’s penis extrude from this slit is a rare sight, which is why our team was so astonished and thrilled to capture the footage from the competition pod.

What is a whale “competition pod” or “comp pod”?

If you have been on a whalewatch eco-adventure you may have heard this term before. It is something commonly witnessed within the humpback whale breeding grounds, such as Hawai`i.

A competition pod is defined as a group of surface-active whales, which consists of one adult female that is being pursued by a group of males. The number of whales in a comp pod varies, from as few as 3 to very large pods with 20 or more animals. The pod composition is always changing; some whales will leave and others will join.

The relative position of the whales within the pod can also change. The males become quite aggressive with each other as they try to gain the position closest to the female and become what is called the “primary escort”.

These competitions can be violent, and it is not uncommon to see blood on the whales as the tubercles on their head become rubbed raw in the heat of the battle. Behaviors often observed are head lunges, peduncle throwing, bubble blowing, jaw clapping, trumpeting and, of course, lots of splashing and blowing. Whales generally do not breach in a competition pod.

Humpback whale with raw tubercles on head from competing with other whales.

How do whales mate and reproduce?

So, why do they compete like this? Well, the reason is reproduction; the males are hoping that the female in the group will be receptive to mating.

As you can see in the video, the animal is swimming toward another whale with the penis clearly visible. It is not known if the whale being approached is a male or female, and research indicates that males can direct a penis extrusion toward either sex. It is not clear what function this behavior serves in a competition pod, but we are excited to share our footage.

While the primary purpose of humpback whale penis extrusion is thought to be for reproduction, there are other theories that suggest it may serve additional purposes. Some scientists believe that the length of a whale’s penis may also play a role in territorial displays or dominance hierarchy among males. In order to be successful in mating, male humpback whales must compete with other males and impress females with their size and strength. The extrudable penis may have evolved as a way to give males an advantage in this competition.

Interested in learning more about whales and other marine life?

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*Footage collected under NMFS Research Permit #16479.