Some Deep Sea Animals Use Hydrothermal Vents to Incubate Their Eggs

Researchers from the University of Rhode Island and the Charles Darwin Research Station have discovered that deep sea skates incubate their eggs next to hydrothermal vents in order to get them to hatch faster, according to a study in Scientific Reports.

The team first made note of this strange behavior during a expedition to the Galapagos Islands in 2015. They found numerous deep-sea skate egg cases that were net to the hot water emitted from hydrothermal vents, a process that appeared to accelerate embryonic development. 

This is the first time in history that such behavior has been recorded in marine animals. As a result, it could change the way scientists view certain aquatic species.

Researchers recorded the egg locations and then measured the water temperatures at each one. That revealed the eggs were likely intentionally placed in regions where water was above the normal average.

“The eggs weren’t right next to the active vents, because the water can get so hot – hundreds of degrees – that it would kill them,” said study co-author Brennan Phillips, a professor at the University of Rhode Island, according to Phys.org. “We found most of them in the lukewarm water not far from the vents and near some extinct vents.

The team analyzed 157 egg cases, and DNA analysis showed that they all came from the Pacific white skate, a underwater relative of sharks and rays. Researchers found roughly 58 percent of the cases within 70 feet of the vents, and nearly 80 percent were laid in water that was hotter than the background temperature.

While past research has shown shark and ray eggs near hydrothermal vents, nobody had ever put the connection together. Not only that, but there are a few land animals that show such behavior as well. For example, a bird in Tonga known as the Polynesian megapode often nests in volcanically-heated soils.

The findings calls into question what other marine life may use this strategy to help their eggs grow. Hydrothermal vents are used by various species for a number of reasons, and this adds to that list.

“Seafloor volcanism comes and goes, and it is often one of the causes of mass extinctions,” added Brennan, according to ZME Science. “It’s interesting to me that we’re seeing sharks and skates thriving around volcanoes and vent sites, like they’re especially resilient and have evolved to withstand the hot water environment.”