Hawksbill sea turtles happily flap through the world’s tropical oceans with bellies full of glass-like fragments. Researchers examining the turtles’ digestive tracts would be wise to take care not to slice their hands on shards of the mineral silica that form the skeletons of sea sponges, a mainstay of the hawksbills’ diet. “Few other organisms will eat these sponges,” says José Urteaga, an expert in sea turtle conservation and the director of marine partnerships at Wild Earth Allies, a wildlife conservation group. Named for their bird-like beaks, adult hawksbills can munch an average of around 1,200 pounds of sponges a year. Plucking sponges from the reef prevents the glassy invertebrates from overpopulating and creates gaps in the reef where young corals can attach and grow. “Hawksbills are like the gardeners of coral reefs,” says Urteaga. 

Sadly, climate change threatens the corals these reptilian gardeners tend and inhabit. And hawksbills are also threatened because of their beauty. People have hunted the turtles for millennia to harvest their rich, glossy brown shells, which blaze in the tropical sun with honey-colored streaks. Ancient Egyptians, Greeks and Romans used the lustrous material to craft bowls, bracelets, combs and other luxury items; more recently it has served as the source of “tortoiseshell” eyeglasses and other items (a misnomer, since the marine reptiles are turtles, not land-dwelling tortoises). 

The shell’s popularity had predictable consequences for the turtle. Now critically endangered, hawksbill numbers have declined by an estimated 80 percent or more in the last century. Trade of the species was outlawed internationally in 1977, but the robust black market, primarily in Southeast Asia, remains a significant threat to their recovery. Stopping illegal trade is a challenge in part because shells and trinkets are often confiscated in a different country from where turtles are poached, making it difficult to know where protections for the species are most needed. To help untangle this mystery, in 2022 the World Wildlife Fund launched an initiative called ShellBank, which aims to use genetic analysis to trace sea turtle products to their points of origin. ShellBank works by collecting genetic material from illegally traded turtle parts, then comparing those genes with a database of sea turtle DNA collected from individuals in their home waters around the world. By working to establish genetic “fingerprints” unique to each region, investigators hope to match any given mysterious shell’s DNA to its provenance.

So far, the database contains some 13,000 entries for hawksbills and green sea turtles, but the team is hoping to add more sea turtle species and see increased policy and conservation results within the next one or two years, according to Christine Madden, ShellBank’s director and co-founder. Twenty-eight countries are already working with ShellBank or have expressed interest in it, some contributing DNA from seized turtle parts. To date, the program has trained 120 law enforcement officers and 75 local researchers in Southeast Asia to collect, handle and analyze the necessary genetic material. Their shared goal: “We want to use ShellBank to dismantle illegal trade in sea turtles,” Madden says.