An underwater robot came across a surprising sight on the seabed: thousands of sharks having a pajama party.

This remote-controlled rover discovered the Port Jackson sharks’ pajama party off the coast of Australia.

This strange underwater scene took place in the Beagle Marine Park – a protected underwater area in Bass Strait, the passage between Australia and Tasmania.

A team of marine scientists from the Institute of Marine and Antarctic Studies (IMAS) at the University of Tasmania sent a remotely operated vehicle to take underwater photographs of this park.

This high-tech robot – equipped with seven cameras – discovered these sharks resting motionless, forming a carpet on the seabed.

“Thousands of sharks lay close together like a carpet on the sea floor,” said Jacquomo Monk, IMAS tour guide.

The IMAS team is conducting a two-week exploration mission of the park on board the research vessel MRV Ngerin.

Mysterious gathering

The mysterious gathering involved only female Port Jackson sharks, which are native to the south coast of Australia. These sharks have distinctive features, including blunt noses and head ridges.

These marine animals, which can grow up to 1.65 meters long, are usually solitary. They rest during the day and use the darkness to hunt squid, octopus and crustaceans. Port Jackson sharks are not an endangered species.

Interestingly, the team had observed a similar gathering before, but this time there were more sharks.

“Seeing them twice in a 3,000-square-kilometer park is like looking for a needle in a haystack,” Monk said. “It was very exciting when we managed to cross a rise in the reef and catch a glimpse of the sharks dozing 65 meters below the ship, almost in the same spot as six years ago.”

The scientists were amazed to discover that the entire group consisted entirely of females. “One of the interesting discoveries we made this time is that the beagle group appears to consist entirely of females,” Monk added.

“This raises more questions than it answers, but we know that males and females of this species often live apart except for mating,” Monk explained in the press release.

The exact reason for the presence of the female sharks is still unclear. One plausible hypothesis is that they are feeding on the abundant doughboy scallops in preparation for their upcoming migration north to reproduce.

Monk emphasizes that her presence in this region once again demonstrates the importance of this area for her.

Surveying the underwater park

These sharks are visible to divers in the shallow waters of New South Wales and Victoria, where they mate in late winter and then lay their distinctive spiral-shaped eggs on the reefs for protection.

They conducted the first survey of the Beagle Marine Park about six years ago. This two-week expedition aims to identify possible changes in the park.

Beagle Marine Park is a treasure trove of marine life. This marine reserve preserves rocky reefs and stunning sponge gardens, and serves as a feeding ground for island-nesting seabirds. Protecting this unique ecosystem is vital to the health of our oceans.

The expedition is funded by the Australian Government and the Southern Australian Coastal Research Vessel Fleet.