After 500 Million Years, Doomed to Decorate Toilet Tanks
Posted by Richard Conniff on September 2, 2016
by Richard Conniff/Takepart.com
Humans have for centuries coveted the chambered nautilus for its elegantly spiraled shell. But too much beauty can be a dangerous gift. We buy nautilus shells in unbelievably huge numbers, with the United States alone importing 789,000 of them during one recent five-year period, mostly to gather dust as knickknacks. As a result, chambered nautilus populations appear to be crashing in their deep-sea Indo-Pacific habitat.
Later this month, a conference in South Africa will take up the question of what to do about it. Four nations, including the United States, have proposed protecting the nautilus under the Convention on International Trade in Endangered Species. A CITES II listing would not ban the trade but would sharply limit it, according to Frederick Dooley, an evolutionary physiologist at the University of Washington.
The Center for Biological Diversity has also petitioned the U.S. Fish and Wildlife Service to protect the chambered nautilus under the Endangered Species Act, which would completely end imports. (The nautilus is found in American Samoa, a U.S. territory. But its range extends from Indonesia to the Philippines.)
Dooley, coauthor of a recent review of nautilus biology, says he has seen nautilus shells being sold by the basketful in Hawaii tourist shops for as little as $4.99 apiece. If someone has bothered to polish the shells to bring out their pearliness, the price may go up to $9 apiece. “They mostly end up being stuck on
the back of the toilet,” he said. You can also buy them on Amazon for $26, and the higher-quality ones sought by serious collectors can sell for upwards of $100.
Most of the nautilus catch now comes from the Philippines. With other fisheries there depleted, fishermen now set traps 1,000 feet deep to harvest the nautilus as one of their last remaining meal tickets. But for all the work put into it, the catch has declined 80 percent since the 1980s.
Most people, on both the buying and selling sides, have little grasp of what they are dealing in. The nautilus is a cephalopod, related to the squid and the octopus, and “people think of squid and octopus being quick to reproduce,” said Dooley. But the chambered nautilus is not calamari: Recent research has demonstrated that it is rare in the wild and takes about 15 years to reach sexual maturity.
Our standard image of “very long-lived, slow-to-reproduce animals” is a giant tortoise or an elephant, said Lauren Vandepas, a doctoral student who collaborates on the nautilus research. We don’t think of invertebrates that way. But this is a mistake.
One other factor makes large-scale commercial exploitation misguided: The nautilus has survived largely unchanged for half a billion years and is thus older than almost anything else alive on Earth. “Somehow this type of organism—the ammonoids and nautilus—have lived for 500 million years and have survived five mass extinctions,” said Dooley, “and now humans are wiping them out.”
The researchers are concerned that local extinctions, in the Philippines or elsewhere, could threaten the entire nautilus population. They have found remarkably little genetic variation among nautilus populations, even ones separated by vast stretches of open ocean. The nautilus moves by jet propulsion, but it typically travels only a mile or two in a day. Yet the genetic uniformity of different populations suggests that they are somehow interbreeding. One possibility is that each population is essential as a stepping-stone allowing the flow of genes across the entire Indo-Pacific meta-population. Removing one stepping-stone could thus have much broader implications, leading to permanent isolation of populations.
When that happens, said Dooley, “you get speciation”—that is, isolated populations become separate species—“or extinction, and extinction is a lot more common.”