For most divers, few underwater spots match the visual thrill of a kaleidoscopic coral reef teeming with colorful fish. For Jeff Milisen, a marine biologist and photographer in Kona, Hawaii, there is no better place to dive than an open stretch of the deep ocean. At night.

“There’s a lot of nothing,” he said. “There is no floor, no walls, just this space that goes into infinity. And one thing you do realize is that there are a lot of sea monsters there, but they are tiny. “

Of course there are also big monsters like sharks. But the creatures Mr. Milisen is referring to are part of a daily movement of larval fish and invertebrates that rise to the surface each evening as part of one of the largest migrations of organisms on the planet. The emerging hobby of taking pictures of them is known as black water photography.

Most larvae are no bigger than a fingernail; others are even smaller. And they can easily be mistaken for seaweed or floating litter. Up close, the animals on a safari with a camera captured with a special lens called a macro can appear as big as wild animals on a safari – a safari on another planet.

Five years ago, Mr. Milisen began sharing his photos on a Facebook group, and there he discovered a community of passionate night adventurers who took pictures of creatures that had rarely been seen before. Mr. Milisen and other members of the community, the Blackwater Photo Group, were amazed and amazed at what they were photographing. They started reaching out to fish scientists and asking for help in figuring out what they were seeing.

Even the most experienced specialists reacted in disbelief.

“The number one thing people, scientists themselves, ask is, ‘What the hell is this?'” Said Ned DeLoach, a veteran underwater photographer who has published eight books on marine fish with his wife Anna and writer Paul Humann. “Why these images are so spectacular and popular is that they are so otherworldly. People never imagined such creatures existed and that attracted photographers. “

David G. Johnson, curator of fish at the Smithsonian National Museum of Natural History, was one of the first scientists contacted by members of the Facebook group. He said he was instantly impressed with the pictures.

“You have behavior, colors,” he said. “It really is a huge step forward in what we can learn about the early life history of fish.”

While the blackwater hobby is on the rise and gaining followers around the world, more and more photographers have captured stunning images and videos that reveal a secret world of bizarre, tiny animals that scientists have struggled to understand for decades. Many of the images have gone viral on social media, and some have recently won major underwater photography awards.

Now scientists like Dr. Johnson formalized the collaboration with blackwater photographers.

In an article published Tuesday in the journal Ichthyology & Herpetology, scientists from Hawaii, along with Dr. Johnson and other Smithsonian staff outlined how they hope to attract more nocturnal underwater photographers, most of whom have no scientific background, to participate in marine research. If the photographers could collect samples of the tiny animals they are photographing, DNA could be extracted and analyzed.

So far, the scientists who led the effort have recruited about a dozen divers who have collected more than 60 samples for analysis. Others are in preparation.

“We are building a collection that has a live image for the first time,” said Dr. Johnson. “We get the sample and make a DNA record attached to it.”

He expects scientists with a knack for underwater photography to join the effort. Marine researchers hope that studying images of animals photographed in their natural habitat and combining those images with data obtained from techniques such as dissection and DNA barcoding can provide a knowledge of how these animals have changed over time change and why they behave this way will expand significantly. Ideally, the work will also shed light on the mysterious daily migration of creatures known as daily vertical migration, which occurs every night in every ocean around the globe.

The daily vertical migration involves trillions of tiny animals, many in the larval stage, that rise from great depths of 1,000 feet or more to just below the surface to feed. The journey takes place at night, scientists believe, because it allows animals to evade predators with larger fish that visually locate their prey. The fry return to the lightless depths before sunrise.

Like many insect species and frogs, most marine fish and invertebrates see and behave very differently in their larval stages than they do as adults. The fish larvae are often adorned with flamboyant pouring appendages to help them navigate the currents or mimic other species like poisonous jellyfish. Some have huge eyes and send out a rainbow of iridescence that would not be out of place at Tiffany’s under a glass counter.

Most marine fish and some marine invertebrates go through this two-stage life cycle. Scientists believe that the drastic change in shape is a product of evolution and natural selection.

“Larvae and adults each live in a completely different evolutionary arena,” said Dr. Johnson. “The larvae live on open ocean currents, which are different from those on which they will settle, such as the sandy bottom, a coral reef or the deep sea.”

The larval stage of many marine animals takes place in the open ocean, which is difficult to study and little is known about. Almost all previous understanding of what these animals look like comes from expeditions they collected in large conical devices called plankton nets that are pulled behind research vessels. The technique began over 150 years ago and gained importance with the Challenger Expedition organized by the British government from 1872 to 1876. Some great advances in technology have been made since then, but the basic engineering is largely unchanged.

Plankton nets pull the animals into a large open ring and guide them into a vessel called cod. When water is forced into the jar, the animals are easily crushed and usually die before they reach the surface. Many creatures, such as jellyfish, salps and glittering, spherical animals called ctenophores, are so sensitive that they are formed into gelatinous goosebumps that researchers pull from the handfuls of glasses on boats. The intact animals are fixed in an alcohol solution that prevents them from decomposing but turns them ghostly white. Often the delicate filaments and fins break off, making it impossible to know how the animals looked and behaved during their lifetime.

“These filament attachments are extremely important,” said Luiz A. Rocha, marine biologist and fish curator at the California Academy of Sciences who is not involved in the project. He said they can be used for mimicry, movement, or camouflage.

“Because all of this information is lost when it is collected on the networks, the photos can open up a whole new area of ​​research to understand why they have these functions and what they are used for,” he said.

Observing fish larvae in open water is not new, but has mostly been practiced during the day. The technique known as blue water diving began in the 1980s when a group of California scientists, hoping to overcome problems with plankton nets, began pulling out boats while the sun was blazing over them.

William M. Hamner, a retired ecologist and evolutionary biologist at the University of California at Los Angeles, was a pioneer of blue water diving and developed many of the open ocean drifting and diving techniques used by black water divers today.

“The fact that we started with blue water is simply because no one cared enough about plankton at the time to go out of their way to see them in the wild, and I did,” said Dr. Hamner.

In both blue and black water diving, divers typically travel well offshore, often 10 miles or more, where the ocean floor can be several thousand feet below. They descend 50 to 100 feet under the sea while clinging to a line suspended from a boat or buoy on the surface.

However, in blackwater diving, powerful underwater lights are attached to a tether to illuminate the water, which often attracts animals, including sharks. The job is not for everyone.

“There is a whole new sensory experience when there is no top or bottom,” said Ms. DeLoach, one of the photographers. “I think I got the closest to space.”

For photographers, it almost becomes an addiction to take a picture of something that has never been observed or even photographed.

“What’s really fascinating is when you send something to the scientists and they have no idea what it is,” said Steven Kovacs, a dentist in Palm Beach, Florida and a frequent contributor to the Facebook group who has been blackwater diving for five years operates years. “Or it’s the first time you’ve seen it. This is one of the greatest thrills of all. “

The photographers have reason to be happy. Some scientists say the images, coupled with DNA from collected larvae, have the potential to revolutionize the study of larval fish.

“We believe this approach will open a new window to our understanding of these larvae and raise exciting questions for future research,” said Ai Nonaka, a Smithsonian researcher and lead author of the paper.

Dr. Johnson hopes the project will inspire a new generation of underwater photographers to become citizen scientists and participate in research.

“We’ve been doing this for four to five years, but it’s still new,” said DeLoach, who and his wife were collecting samples for the Smithsonian in 2019. “There is so much that has not yet been discovered. It is quite convenient to have a copy with your name on it in the Smithsonian Collection.”

Other scientists studying larval fish are happy to give photographers the credit they deserve.

“I think this is one of those special cases where underwater photographers actually did something very valuable and cool before science,” said Tom Shlesinger, a Florida-based marine biologist converting to blackwater photography. “It really opened my eyes and my mind that we actually know very little about what goes on in the ocean at night.”