“Spectacular” moment: Thousands of sleeping sharks are spotted on the seabed – experts are baffled because they are all girls
Thousands of sharks have been observed napping on the sea floor – and to the amazement of scientists, they are all female.
The “shark pajama party for girls only” has left experts baffled as they cannot explain why they are in this exact spot and without any males.
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They were first spotted here six years ago during the first survey of the Beagle Marine Park in Bass Strait off the coast of Victoria, Australia.
Port Jackson sharks are commonly found in rocky environments or on the seabed in southern Australia.
They can reach a length of about 1.65 meters and are nocturnal, meaning they sleep during the day and hunt squid, octopus and crustaceans at night.
The Port Jackson sharks are considered to be quite friendly and divers regularly come into contact with them.
Now the “spectacular” but mysterious sleepy gathering of Port Jackson sharks has been rediscovered with the help of an underwater robot on board a research vessel of the South Australian Research and Development Institute (SARDI).
Dr Jacquomo Monk of the University of Tasmania’s Institute of Marine and Antarctic Studies (IMAS) said the sharks were “packed together like a carpet stretching across the seabed”.
“We were hoping to see the sharks again on this exploration,” the tour guide explained.
“Finding them twice in a 3,000 square kilometer park is like looking for a needle in a haystack.
“It was very exciting when we managed to cross a hill in the reef and catch a glimpse of the sharks dozing 65 metres below the ship, almost in the same place as six years ago.”
Port Jackson sharks have been shown to mate in late winter. They have a characteristic spiral-shaped egg case that they lay on reefs for protection.
It is common for male and female Port Jackson sharks to live separately, but scientists cannot explain why this “appears to only be the case in females.”
However, they may go there to breed or “fatten up” before moving on to the areas where they normally lay their eggs.
“This raises more questions than it answers, but we know that males and females of this species often live apart except for mating,” Dr. Monk continued.
“We don’t know exactly why the females are here.
“Perhaps they are feasting on the local delicacy – doughboy scallops – before making the long journey north to lay their eggs.
“Seeing them again shows us that the area is important to them.”
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Sharks in Port Jackson: Important Facts
The sharks of Port Jackson are considered to be quite friendly, as no fatal attacks on humans have been reported so far.
It is a species of bull shark in the Heterodontidae family that is found throughout southern Australia.
Port Jackson sharks are known for their characteristic large, blunt head with pronounced forehead ridges and dark brown, harness-like markings on a lighter, gray-brown body.
The species is often found in rocky environments or near the seabed.
Female Port Jackson sharks typically reach sexual maturity at 11 to 14 years of age, while males reach sexual maturity earlier, at about 8 to 10 years of age.
