MOSS LANDING >> The black seadevil is named for its baleful ugliness. With that vicious gape, the females can eat fish of a larger size. To lure her prey, she jerks the luminescent orb dangling from the “fishing rod” on her forehead.

The males are tiny in comparison and live shorter lives with one purpose, to find a mate. He bites her gelatinous flesh, living as a parasite and never letting go. Their tissues and blood systems fuse with the females’. Her body feeds him food and oxygen and provides the necessary hormones to survive.

“If they don’t find a female, they drown,” said Ted Pietsch, professor at the University of Washington and expert on the deep-sea anglerfish. “They’re not even properly equipped to eat.”

With simplified bodies, the males lack the same nightmarish fangs and a proper gut.

The black seadevil is a species of anglerfish and rarely seen. It has never been captured on video in the wild until this week.

Not much is known about these denizens of the deep beyond their life spans and their reproductive biology.

“A video would tell us a lot about how it moves, swims, orients to gravity,” Pietsch said.

While cruising the Monterey Bay, scientists with the Monterey Bay Aquarium Research Institute spotted the cagey creature at 2,000 feet below the surface, but it also lives in the freezing, crushing water four times deeper.

“We’ve been diving out here in the Monterey Canyon regularly for 25 years, and we’ve seen three,” said Bruce Robison, research division chairman of the aquarium’s research institute.

The Monterey Canyon is one of the few places where scientists can explore the deep sea. Though an arguably unfair but often used comparison, more is known about the surface of the moon than the bottom of the ocean where there is no sunlight.

Robison leads an international team of researchers studying how much oxygen deep-sea animals use. They captured the 3.5-inch black seadevil to study and don’t know how long it will survive.

As ocean temperatures rise, the amount of oxygen in the water decreases. In the past three decades, the bay water has warmed a tenth or two tenths of a degree.

“You can see that the temperature is creeping up slowly, probably because of global warming,” Robison said. “If the temperature continues to rise and the amount of oxygen continues to decrease, things are going to change.”

His team is researching the possible impacts of even a slight change in temperature on animals in the deep sea, where the pace of life is slower due to less oxygen and the near-freezing temperatures 40 degrees Fahrenheit in the Monterey Bay.

The scientists built an instrument to record the respiratory rates of animals. They first measure the amount of oxygen in an enclosed area of air or water, as in this case, with the animal and monitor the changes in oxygen levels over time.

Marine life in shallow waters are already being affected by an increase in carbon dioxide and warming temperatures, said Brad Seibel, an assistant professor of marine biology at the University of Rhode Island.

But if climate change continues, the deep sea creatures will endure the impacts next, and they are even more sensitive to environmental changes.

“Animals that live in the oxygen minimum zones are adapted to low oxygen, but they might be close to their limit,” Seibel said.

Beyond the physiological harm due to a lack of oxygen, such as stunted development, deeper animals would have to come to shallower waters.

And animals near the surface would have to swim to colder waters. These mass migrations would alter ecosystems as food and predators might not shift in the same way, Seibel said.