Two male megamouth sharks were observed swimming together, one measuring approximately 3.7 meters long and the larger one at 4.6 meters, with unclear gender. They may be courting or foraging.
The pair of megamouth sharks, with the smaller one being male, swam close to a fishing boat. (Video: Andrew Chang/David Stabile).
Despite being one of the largest fish species in the ocean, the megamouth shark (Megachasma pelagios) remains extremely mysterious, with scientists knowing very little about its past and biological characteristics, according to IFL Science on March 27. This species has only been spotted 273 times since 1976, and it wasn’t until last year that two megamouth sharks were seen swimming together.
On September 11, 2022, off the coast of San Diego, California, USA, anglers discovered two megamouth sharks. They captured short footage of the sharks, which was then shared on social media and forwarded to scientists. The research team analyzed the video and interviewed the people on the boat. Their study was published in the journal Environmental Biology of Fishes.
The sharks swam about 45 to 60 meters away from the fishing boat. The larger shark, approximately 4.6 meters long, seemed to be circling around the smaller one, measuring 3.7 meters. The smaller shark, identified as male, continued to dive deeper as the boat approached, while the larger (gender unclear) swam towards the boat at a different depth.
The pair did not feed during this time. The larger shark made several passes near the boat, while the male mostly stayed in deeper waters, surfacing slowly only once near the side of the boat.
The smaller male megamouth shark swimming beneath the larger shark. (Photo: Environmental Biology of Fishes).
The research team proposed two main hypotheses for why the megamouth sharks were swimming together:
The first is that they were foraging together. Scientists know very little about the diet of this species, but it is believed to be filter-feeding, primarily consuming mollusks, squid, and other soft-bodied organisms. Although the filmmakers did not observe any feeding behavior, the presence of the fishing boat may have disturbed them. People on the boat also reported seeing many moonfish and soft-bodied creatures around. Moonfish and megamouth sharks are often spotted together, and both feed on soft-bodied organisms.
The second hypothesis suggests that the megamouth sharks were engaging in courtship behavior. The research team noted that the male shark’s behavior of following the larger shark is similar to courting behaviors seen in other shark species. They also pointed out that in other shark species, mating opportunities may arise during foraging gatherings. No mating attempts occurred during the encounter with the boat, but researchers noted that sightings of mating among filter-feeding sharks are extremely rare.
Based on the video and previous insights, the research team concluded that the two sharks were likely engaging in pre-mating behavior. They also remarked that with the rise of social media, awareness, and maritime traffic, similar reports may become more common and provide deeper insights into the lives of these mysterious megamouth sharks.
