Toothy fish loses and replaces 20 teeth daily, keeping its prey on its toes

Lingcod is a type of fish that grows quickly, up to 1.5 metres and 36 kilograms – and lives about 20 years. While the National Oceanic and Atmospheric Administration (NOAA) of the US Department of Commerce says it has “18 large, sharp teeth” the Smithsonian explains “it has more than 500 needle-sharp, tiny teeth lining its two sets of jaws.”

According to a new study, “Pacific lingcod will lose up to 20 teeth a single day—and grow them all back,” the Smithsonian reports. The fish, with a blueish green flesh when uncooked, is a popular edible choice, yet you would not want to be its prey, if science is to be believed.

"Every bony surface in their mouths are covered in teeth," says Karly Cohen, a doctoral candidate at the University of Washington and a co-author of the new study, to Live Science’s Cameron Duke.

According to NOAA, ”Larvae feed on zooplankton (tiny floating animals), including krill and larval crustaceans such as lobster and crab. Juveniles feed on small fish. Adults are aggressive predators and feed primarily on bottom-dwelling fish (including smaller lingcod), squid, octopi, and crab. Marine mammals, sharks, and larger lingcod prey on juvenile and adult lingcod.”

This omnivorous animal, according to Live Science, has “Instead of incisors, molars and canines ... hundreds of sharp, near-microscopic teeth on their jaws. Their hard palate is also covered in hundreds of tiny dental stalactites. And behind one set of jaws lies another set of accessory jaws, called pharyngeal jaws, that the fish use to chew food much in the same way humans use molars.”

Emily Carr, an undergraduate student at the University of South Florida and the study’s lead author, tells National Geographic that the fish “have a set of upper and lower jaws, just like ours, but they’re more mobile—they can be thrown forward and spread out.” She explains that “If you look inside the mouth on their palate, it’s also covered in teeth.” Then, all the way at the back of the throat, right before their esophagus, there are the pharyngeal jaws, tooth-studded bony platforms made out of modified gill arches, National Geographic reports.

National Geographic describes the lingcods’ eating scheme as its first set of jaws shooting forward, and dragging prey into the mouth where the inner pharyngeal jaws get to work crushing and shredding. “For this strategy to succeed, the lingcod relies on needle-sharp teeth, which are prone to breakage. But how to keep its bite from going dull? The strategy seems to be: Constantly grow new teeth. Lots of them,” Elizabeth Anne Brown for National Geographic explains.

In the study, titled 'The moment of tooth: rate, fate and pattern of Pacific lingcod dentition revealed by pulse-chase,' the authors write: “Pulse-chase is a fluorescent technique that differentially colours developing mineralized tissue. We present in situ tooth replacement rate and position data for the oral and pharyngeal detentions of Ophiodon elongatus (Pacific lingcod). We assessed over 10 000 teeth, in 20 fish, and found a daily replacement rate of about two teeth (3.6% of the dentition).”

In human terms, that’s like losing a tooth every day. “Kind of makes braces useless,” jokes Adam Summers, professor of biology at the University of Washington and co-author of the study. “And brushing.”

The team first put the 20 Pacific lingcod in a tank dyed with red seawater. Then they changed the water to regular seawater for 10 days. Finally, they used seawater that was dyed green as the final stage to find out which teeth would be dyed both red and green, indicating they hadn’t been replaced. The new teeth would be green only, indicating new growth.

Annie Roth, writing for the New York Times, notes: “After collecting and examining a total of 10,000 teeth, the scientists were able to determine how quickly lingcod lost and regrew their teeth and which teeth were replaced most often.”

“It’s absolutely crazy how many teeth they replace,” Carr tells the New York Times. She, according to the New York Times, “counted all 10,000 teeth by herself, [and] noticed tooth replacement did not occur at the same frequency across the lingcods’ jaws.”

The study’s authors realised that, the New York Times reports, “teeth are replaced more frequently in the back of the mouth, where most of the chomping and crushing take place.”

Kory Evans, a fish ecologist at Rice University in Houston interviewed by the New York Times says “The duller a lingcod’s teeth are, the harder it is going to be for it to hold on to its prey. So having the ability to shed teeth and replace them is pretty important.” In order to make it as a lingcod, Dr. Evans notes, “you need sharp pointy teeth and all your teeth need to be on point.”