Topping the new list, at number one is the largetooth sawfish (Pristis pristis), which is also the highest-ranking EDGE species in the world.  Each species on this list has few or no remaining close relatives, representing distinct branches of the tree of life and making them truly irreplaceable.  If they go extinct we will have nothing left like them on the planet.

EDGE Sharks co-ordinator and marine biologist, Fran Cabada said: “Sharks, rays and chimeras – making up the cartilaginous fish, have been around since the age of the dinosaurs, but due to human activities, their modern relatives are facing threats all over the world. They’re found in almost every aquatic environment and as many are apex predators, i.e., at the top of the food chain – they’re crucial to maintaining healthy ecosystems.

“The new EDGE Sharks and Rays list gives us the opportunity to highlight the most unique sharks and rays on our planet which are also the most endangered, so that we can target conservation efforts where it’s needed most. Many are overlooked and poorly known, so conservation actions targeted at these survivors of ancient lineages should be prioritised.”

First established in 2007, ZSL’s EDGE of Existence program provides conservationists worldwide with a scientifically rigorous method of focusing their conservation efforts on animals and plants that represent a significant amount of threatened evolutionary history.