Exploring a chamber of nautilus secrets

As a second grader, seven-year-old Ellen Umeda charted her hopes and dreams in a journal, including this entry:

“When I grow up, I want to work at the Monterey Bay Aquarium.”

Aquarist Ellen Umeda is living a childhiood dream: working at the aquarium and raising chambered nautilus hatchlings.

Today, Aquarist Ellen Umeda is doing just that—and breaking new ground as she raises one of the most challenging species housed at any aquarium: the chambered nautilus.

The Sunnyvale native and UC San Diego graduate is taking the lead in caring for our first-ever chambered nautilus hatchlings, and trying new approaches that could someday lead to a breakthrough in raising and breeding these beautiful, shelled cephalopods.

“I’m lucky to be working with an animal that’s still quite a mystery,” Ellen said. “There are so many unknowns.”

Unsolved mysteries

No one, for example, has seen a nautilus egg in the wild—perhaps because they’re laid at depths beyond where recreational scuba divers can safely go. They can range below 100 meters (330 feet deep)—but do the young develop in warmer waters, closer to the surface, or in cooler, deeper waters?

A chambered nautilus hatchling begins to emerge from its egg in a behind-the-scenes nursery. It’s one of hundreds laid by adults in our “Tentacles” exhibit.

These are some of the unknowns Ellen has to contend with as she tries to take the rearing of chambered nautiluses beyond the point her colleagues have achieved with this ancient species from the Indo-Pacific region.

As a member of the team that cares for the animals in our Tentacles special exhibition, Ellen raises many of the species we exhibit, including cuttlefishes and squids. She and her teammates have built a successful track record with species that no other aquarium had raised before.

Chambered nautiluses present an entirely new set of challenges. She’s been wrestling with those challenges since the first nautilus egg hatched in late July. Several others have hatched since then.

Thirty years of attempts

Starting in the 1980s, colleagues at Waikiki Aquarium, Omaha’s Henry Doorly Zoo and Aquarium, and Birch Aquarium in La Jolla began hatching and raising chambered nautiluses they kept on exhibit. None of the hatchlings survived much more than a year.

As we rear baby chambered nautiluses, we also take measurements regularly to document their rate of growth.

Toba Aquarium in Japan has also had success hatching nautiluses, with a few individuals surviving three years or longer—including one individual that lived four and a half years.

After that, the animals died, for reasons unknown, Ellen says.

“When I asked my colleagues what happened, they all said: ‘We have no idea. They became buoyant in the water column and stopped eating.’”

Ellen has the benefit of their experience. She knows the water temperatures at which the hatchlings were raised, and what was in their diet.

‘What can we do differently?’

“They all got to a certain point,” she said. “Now I’m asking: ‘What can we do differently?’”

Baby nautilus are kept in low-light conditions, similar to the deep water they inhabit in the wild. They are hand-fed by Ellen Umeda and other aquarrists.

It’s an approach that’s worked well for us in the past. Our aquarists were the first to culture several species of jellies and the first to consistently raise multiple generations of comb jellies. They were also the first to exhibit young white sharks and get them to take food while on exhibit, and then to successfully return them to the wild.

The opportunity to work with new species is built into the foundation of the Aquarium, says Vice President of Husbandry Jon Hoech.

“When the Aquarium was first being planned, David Packard and the other founders visited many other aquariums,” he says. “Each time they asked, ‘If you could do it all over, what would be different about your facility?’ One of their takeaways was: Include more behind-the-scenes space for the animal care staff to work. So, we have room in our galleries to raise animals before we know we’ll be able to keep them on exhibit.”

Another piece of the foundation came from our original husbandry director, David Powell, Jon says.

“Dave insisted that our aquarists have time in their schedules to work on projects, and not just have their days filled with routine maintenance of our living exhibits,” he says. “They’re encouraged to try new things and take risks. That’s why we’ve been able to bring so many new species to the public, year after year.”

Tapping others’ expertise, seeking a breakthrough

Ellen is drawing on the experience of colleagues at other aquariums, and the resources here in Monterey, to seek a breakthrough in chambered nautilus care.

Nautilus eggs are kept in a nursery holding area, with water temperature and light carefully controlled.

She’s now caring for more than 150 nautilus eggs, and fewer than a half-dozen hatchlings. They’re housed under low-light conditions, some in cooler water and some in warmer, in behind-the-scenes holding areas.

She’s experimenting with the water temperature at which she’s keeping the eggs laid on exhibit by the adult nautiluses. And she’s working with Curator of Collections Joe Welsh, who’s pioneered the use of pressurized holding tanks for deep-water species.

Is pressure the key?

Ellen believes raising chambered nautiluses under pressure—perhaps even putting eggs in a pressurized aquarium before they hatch—could be the key to solving the problem of the young nautiluses becoming buoyant in the water column, rather than neutrally buoyant and able to maintain their position in the water.

Ellen Umeda and her team are keeping hatchlings like this one, and some developing eggs, in a pressurized aquarium that mimics deep-water conditions where nautiluses live in the wild.

She thinks that the fluid-filled chambers that develop, section by section, in a growing chambered nautilus, may not function properly unless they form under pressure.

“Some of my colleagues thought that might be a solution, but they didn’t have the resources to pursue the idea,” she says. In Monterey, she noted, the Aquarium has a track record of success with deep-water rockfishes that may point the way forward with chambered nautiluses.

“We need to experiment and try different things that mimic their environment in the wild, things that other people haven’t done,” Ellen says. “I hope our animals will live longer, and that a greater percentage of them will hatch and survive. The ultimate goal would be to raise them to adulthood, have them lay eggs, and then raise the next generation.”

That, she admits, is probably a long ways off. Just as she’s benefited from the experiences of her predecessors, she hopes to contribute the next increment of progress.

“It’s all steps,” Ellen says. “Right now, it’s live one more month, and then one more.’”

— Ken Peterson

All photos © Monterey Bay Aquarium. Featured photo by Randy Wilder; all other photos by Tyson Rininger.