It's a fear of many scuba divers: A giant, mysterious object, slowly but inexorably floating up toward you from the deep.
It could be an enormous sea turtle, a curious shark, or some undiscovered creature bent on eating you.
Divers off the coast of Turkey found themselves in a similar situation recently when they stumbled across a car-size ball of gelatinous goo. Luckily for them, their visitor from the deep was a massive ball of squid eggs.
The diaphanous sphere studded with tiny white eggs was probably laid by the red flying squid, says Michael Vecchione, a squid expert with the U.S. National Oceanic and Atmospheric Administration.
“We know that some of the species in that family lay egg masses that look very much like that [in the video],” says Vecchione, who is also the curator of cephalopods—a group including squids and octopuses—at the Smithsonian’s National Museum of Natural History in Washington, D.C. (Read "Scientists Unravel Mystery of Flying Squid.")
A Humboldt squid was responsible for a similar-looking giant squid egg mass seen in the Gulf of California in June 2006. But Humboldt squid aren’t found in the Mediterranean, says Vecchione. The largest squid in the area is the red flying squid, making the species the most likely culprit in this recent sighting.
The red flying squid, which can grow up to 5 feet (1.5 meters) long, didn't deposit the roughly 13-foot-wide (4-meter-wide) egg mass fully formed. The squid mom likely laid a smaller ball of jelly embedded with eggs, which then expanded upon contact with seawater.
Squid egg masses are made of a gelatinous substance that can balloon to enormous sizes, says Danna Staaf, a squid expert and lead author of the study that described the Gulf of California egg mass.
That expansion probably helps to keep the squid embryos far enough apart so that each egg gets enough oxygen, she explains. The jelly also seems to protect the babies from predators and parasites.
In fact, when Staaf and colleagues tried to produce young squid in the laboratory using in vitro fertilization—without the jelly—the developing embryos were plagued with infections.
"It also seems to be necessary for the eggs to develop properly," Staaf says. Without the gelatinous goop, their petri dish squid wouldn't grow correctly. Unfortunately, scientists don't know how or why this happens. (Read about how scientists solved the mystery of the vampire squid's diet.)
A Rare Sighting
Vecchione says that it's extremely rare for people to observe these huge egg masses in the wild for several reasons. First, they're usually too far offshore and too deep for divers to encounter them.
Once a squid lays its egg mass in the water—and it's not a species that attaches its eggs to the seafloor—the gelatinous ball starts to sink very slowly, Vecchione says. It usually ends up around 500 feet (150 meters) deep when the babies are ready to hatch.
The egg balls are also pretty ephemeral. "In this particular family, the embryos hatch very quickly," Vecchione says. "They develop in just a few days." So the egg mass the divers spied off of Turkey was likely only a couple of days old, he says. (Read about other mysterious balls of goo served up by the deep sea.)
Before this instance, "I can only think of two or three published observations from nature," Vecchione says. Egg masses have been observed in captivity in Canada and Japan, but nothing on the scale of what's in the video.
"There’s probably lots and lots of them out there," he says.
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