Sharks: 10 Fascinating Discoveries
Greenland Sharks: The Longest-Lived Vertebrates
Greenland sharks, found in the cold waters near the Arctic, have a lifespan of over 400 years, making them the longest-lived vertebrates ever discovered. Their slow metabolism rate, “just above a rock,” contributes to their extreme longevity. However, this slow-motion living also means they reproduce very slowly, putting them at risk of extinction if their populations are depleted.
Ghost Sharks: Mysterious Creatures with Retractable Sex Organs
Ghost sharks, named for their deep-water habitat and rarity, have recently been found to possess retractable sex organs on their heads. These organs have hooks that male ghost sharks use to grasp females during mating, an experience that is reportedly not very pleasant for the females. Female ghost sharks can store sperm for years in special storage banks in their bodies, waiting for the right time to conceive.
Great White Shark Nursery Discovered Off New York Coast
In August 2017, the conservation group Ocearch discovered a rare great white shark nursery in the shallow waters off the coast of New York. This was the first such nursery found in the northern Atlantic Ocean, and researchers believe the sharks spend the first 20 years of their life there. Little is known about the migratory patterns of young sharks, making this discovery a significant breakthrough.
Reef Sharks: Not the Apex Predators We Thought
Reef sharks have often been depicted as the alpha predators of their habitats, similar to lions in the African savanna. However, research has challenged this myth. Studies have shown that in many areas where sharks have been fished, the population levels of herbivore fish have not changed substantially, indicating that sharks’ influence on their environments is lower than previously thought. Only a few of the largest shark species, such as tiger sharks, actually play the role of apex predator.
Megalolamna Paradoxodon: A Giant Shark from the Past
Megalolamna paradoxodon, a newly described species of giant shark that lived 20 million years ago, grew to the size of a car. Researchers estimated its length to be about 12 feet, making it much larger than most humans but smaller than the infamous great white shark. The species may have been a close relative of other ancient sharks that grew to be five times that size.
Saving Sharks by Encouraging Fishing: A Controversial Solution
Many shark species are under threat from illegal fishing for their meat and fins, as well as bycatch in nets targeting other fish. Scientists have proposed a controversial solution: encouraging legal shark fishing. A study found that only about 4% of shark fishing is currently managed sustainably. A shark fishing policy that takes into account certain sharks’ ages and reproductive cycles could help keep shark populations healthy.
California’s Great White Sharks: A Mysterious Pilgrimage
Every year, California’s great white sharks make a mysterious pilgrimage to a remote spot in the ocean. Scientists are trying to unravel the reason for this behavior. Biologist Salvador Jorgensen has developed durable cameras that can be attached to the fins of sharks to record their movements and shed light on this enigmatic phenomenon.
Two-Headed Sharks: A Sign of Environmental Problems?
Fishermen and scientists have been encountering more and more two-headed sharks in recent years. The cause of this uptick in mutations is still unclear, but some biologists suspect it may be related to infections, pollution, or declining population from shark overfishing.
The U.S. Navy’s Secret Project to Use Sharks as Weapons
During the Cold War, the U.S. Navy conducted a top-secret project to develop sharks as weapons. The plan was to use electric shocks to guide sharks carrying bombs to their destinations and detonate them. The project, which ran from 1958 to 1971, was ultimately unsuccessful.
Lemon Sharks: Unflappable Creatures
Lemon sharks are known for their resilience. A recent study documented a lemon shark that swallowed a steel piece of fishing equipment that pierced its stomach. The shark not only survived the injury but also managed to expel the metal object through its skin. Another study found that tiger sharks have consumed a wide range of strange objects, including birds, bats, porcupines, bags of chips, and even condoms.
