Save the Nautilus! Three new species described from the Coral Sea and South Pacific

Nautiloids were once quite plentiful throughout the oceans, based upon the fossil record. Today, they are represented by just a handful of species, including the newly described Nautilus vitiensis of Fiji, Nautilus samoaensis of American Samoa, and Nautilus vanuatuensis of Vanuatu. These descriptions highlight the concept of allopatric speciation, or biogeographic isolation, where populations are geographically separated from other populations, resulting in a barrier to gene flow. Over time, these populations may eventually evolve into distinct species.

But what does it take to be able to collect the evidence needed to determine if three different populations of nautiluses are, in fact, three different species?

“For me, this is the best/worst part of the overall process, because nautilus fishing is not easy,” explains Dr Gregory Barord, marine biology instructor at Central Campus and conservation biologist at the conservation organization Save the Nautilus. “For our team, it starts with building large, steel traps that are about a meter cubed. Then, we wrap the steel frame (ouch), with chicken wire (ouch) mesh (ouch), create an entry hole (ouch), attach it to a surface buoy with about 300 meters of fishing line, and bait it with (ouch) raw meat, usually chicken!”

“Trap construction may take place on a nice beach or a bit inland in the rain or in a warm warehouse. Wherever it takes place, you will have some memories, I mean little scars, on your hands from working with the chicken wire. Looking down at my hands right now, I can remember where I was by looking at each of those scars… worth it!”

Tossing the traps into the sea at dusk is the easy part, Dr Barord says. Load them on the boat, find the right depth, and tip them over the side of the boat. “The hard part is retrieving the traps the next day, after about 12 hours of the raw chicken scent moving through the currents. There are a number of methods we’ve used to pull the traps up, from mechanical winches, hand-powered winches, float systems, boat pulls, and of course, just pulling with one hand at a time. Invariably, something happens in each location where we are just pulling the trap up from 300 meters one meter at a time, which takes a good half hour at least. But, at least you are getting a VERY good work-out. Eventually, you see the trap and these white little orbs in it and you know you’ve caught some nautiluses and the pulling is almost done, for now.”

The next step is probably Dr Barord’s favorite: “One of us jumps in the water and free dives about 5 meters to carefully (ouch, that chicken wire) reach for the nautiluses in the trap and bring them to the surface. You are face to face with these uniquely, misunderstood organisms who seem like this is just another day for them. For me, this is exhilarating!”

Once on the boat, they are placed in chilled seawater and from then on, the data collection happens fast. “With the living organism in hand, you can start to glean even more of the differences between the species, examining the hood ornaments, or lack thereof,” Dr Barord explains. After some photos, measurements, and non-lethal tissue samples, the nautiluses are released and burped.

“Maybe nautilus burping is my favorite part,” he adds. To do this, the researchers either dive with SCUBA or free dive with the nautiluses, and ensure there are no air bubbles trapped in the shell that may cause them to be positively buoyant. “Imagine, you have one nautilus in each hand and you start swimming down, your feet and the nautilus tentacles pointed toward the surface. At a sufficient depth, you release them and observe their buoyancy. As the nautiluses compose themselves and jet back down to their nektobenthic habitat 300 meters below, you realize you may never see that individual nautilus again, and that nautilus may never see another human, well, maybe they will…”

For him, the impetus for a publication in the scientific journal ZooKeys describing the three new species is rooted in nautilus conservation efforts. Over the last 20 years, he has studied nautiluses from many angles and for over 10 years now, has worked with an international team to address nautilus conservation issues.

“For many nautiluses, probably millions, they were caught in much the same way that our team collected nautiluses,” he points out. “However, their first meeting with humans was their last as they were pulled from the trap, ripped from their protective shell, and tossed back in the ocean, used as bait, or, rarely, consumed. The shell is the attractive piece for shell traders and the living body has no value. It is like shark finning in that sense.”

As a direct result of these unregulated fisheries, populations of nautiluses have crashed, some have reportedly gone extinct, and international and country level legislation and regulations has been enacted.

Currently, there are no known fisheries in Fiji, American Samoa, or Vanuatu so the risk of these populations decreasing from fisheries is low, at the moment. Now, what is the risk to these same populations from ocean acidification, increased sedimentation, eutrophication, warming seas, and over-fishing of other species connected to the ecosystem nautiluses reside in?

“Right now, we simply do not know,” says Dr Barord. “Our conservation efforts started with simply counting how many nautiluses were left in different areas across the Indo-Pacific, then recording them in their natural habitat, then tracking their migrations, and now describing new species. There are still many questions to address regarding where they lay eggs, what they eat, and how they behave.”

All nautiluses have long been grouped together when describing their natural history, but as we continue to uncover the nautilus story, it is increasingly obvious that each population of nautiluses is different, as exemplified by these three new species descriptions.

“This is certainly an exciting time for nautilus research, as we uncover more and more information about the secret life of nautiluses,” Dr Barord says in conclusion.

“I just hope that this is also an exciting time for nautiluses as well, and they continue doing their nautilus thing as they have done for millions of years.”

Research article:

Barord GJ, Combosch DJ, Giribet G, Landman N, Lemer S, Veloso J, Ward PD (2023) Three new species of Nautilus Linnaeus, 1758 (Mollusca, Cephalopoda) from the Coral Sea and South Pacific. ZooKeys 1143: 51-69. https://doi.org/10.3897/zookeys.1143.84427