Brace yourself. To human senses, the gelid waters of the Arctic and North Atlantic oceans are beyond chilling. Because sea water is salty, the waters can actually reach temperatures below what we think of as freezing (as low as 28.8 degrees Fahrenheit instead of the usual 32) and remain liquid. Without protective gear, the human body can withstand maybe 15 minutes of these temperatures before succumbing to unconsciousness; 45 minutes before death.
An artist’s impression of Carcharocles megalodon. (Photo credit: Karen Carr/CC) Large marine megafauna, including megalodon, the largest shark to have ever lived, disappeared during a global extinction event that had previously not been recognized as such. At the end of the Pliocene, between two and three million years ago, the planet entered a [...]
A new analysis of population trends among coastal sharks of the southeast U.S. shows that all but one of the seven species studied are increasing in abundance. The gains follow enactment of fishing regulations in the early 1990s after decades of declining shark numbers.
Researchers at Stanford University's Hopkins Marine Station investigated the role of expanded marine protected areas (MPAs) on grey reef sharks and found that the aquatic no-fishing zones were an effective tool for protecting this near-threatened species. Originating 423 million years ago, sharks are a group of predators that span 490 species and still play crucial roles within their ecosystems. We often characterize these top predators as nearly indestructible monsters but, of course, that's far from the reality: They mature slowly, they don't have high numbers of offspring, and they're under serious threat due to the value of their fins.
A female zebra shark in an Australian aquarium has astounded scientists by producing live offspring asexually, three years after being separated from her long-term mate. While scientists have previously observed "virgin births" in vertebrates such as sharks, rays and reptiles -- a reproductive strategy thought to aid survival during periods of isolation -- this is the first time a female shark has ever been observed reproducing asexually after previously mating with a male.
Using only the DNA from sloughed-off cells floating in the ocean, scientists have been able to determine the population size and genetic properties of one of the world’s largest and most mysterious animals: the whale shark. The work marks the first time researchers have been able to use so-called environmental DNA (eDNA) to estimate the genetic characteristics of an aquatic species, and it could help scientists study the population and health of a wide range of marine animals without ever setting foot in the water.
Two-headed sharks may sound like a figment of the big screen, but they exist—and more are turning up worldwide, scientists say.A few years ago off Florida, fishermen hauled in a bull shark whose uterus contained a two-headed fetus. In 2008, another fisherman discovered a two-headed blue shark embryo in the Indian Ocean.
AMMONIA is as repulsive to most marine animals as it is to land-lubbing ones—and for good reason. It is extremely toxic. But there is an exception. Far from being repelled by ammonia, sharks are actually attracted to it. The longtime assumption has been that this is because it is a waste product, voided into the water by fish and other creatures, that signals the presence of potential prey.
Megalolamna paradoxodon is the name of a new extinct shark described by an international research team who based their discovery on fossilized teeth up to 4.5 centimeters (1.8 inches) tall found from the eastern and western United States (California and North Carolina), Peru and Japan.
Sharks have a big reputation for their teeth. The ocean predators use their buzz saw mouths to efficiently dismantle prey, ranging from marine mammals and sea turtles to seabirds and—as Hollywood likes to remind us—an occasional human.
Scientists found high concentrations of toxins linked to neurodegenerative diseases in the fins and muscles of 10 species of sharks. The research team suggests that restricting consumption of sharks can have positive health benefits for consumers and for shark conservation, since several of the sharks analyzed in the study are threatened with extinction due to overfishing.
Researchers have long assumed that some animals could see through this silvery disguise, thanks to a superpower of their own: the ability to detect a property of light—called polarization—that humans can't see. Octopuses and squid, shrimp and other crustaceans, and some fish such as trout and salmon all have the gift, called polarization vision.