The world-famous Zoological Society of London (ZSL) runs a conservation program focusing on species that represent a significant slice of unique evolutionary history. The Edge of Existence program works to identify the world’s most “Evolutionarily Distinct Globally Endangered” species — hence EDGE.
EDGE is the only global conservation initiative focusing specifically on threatened species that represent a significant portion of unique evolutionary history. The program aims to highlight and protect some of our planet’s unique and interesting species that have few close relatives. Most have unusual looks, lives, habits or genetic make up that make them an irreplaceable part of our natural heritage.
The aim of EDGE
The EDGE program hopes to put these species in the spotlight and thus increase conservation efforts to secure their future. This year (December 2018) the EDGE program launched its first sharks and rays list. Among the oldest of all species on our planet, many inhabited the oceans when the dinosaurs still roamed the earth.
A number of issues, from pollution to unsustainable fishing methods and global warming threaten marine life, as divers know. Unfortunately, many of the most evolutionarily distinct sharks and rays are also the ones facing the most threats.
Taking a look at the list it immediately becomes clear that many of the species divers love most appear: whale shark, thresher, hammerhead, basking, great white, porbeagle and mako sharks, as well as eagle rays.
The list also contains many that will be new to all but the most ardent fans of marine life, including:
Taking up the first four places on the list, these unique creatures have large, saw-like rostrums (nose extensions). Also called carpenter sharks, they are actually a family of rays with the largest of the species reaching up to 25 feet (7.6 m).
Despite its aggressive looks, the sand tiger is actually a fairly placid shark. Uniquely, it can also breath air from the surface. Its reproductive cycle involves intrauterine cannibalism, which means the embryos will eat each other. The shark has two uteruses and in each the largest embryo will eat its siblings once they develop teeth, leaving just two pups that are around 3 feet (1 m) long when they are born.
Inhabiting the coastal waters off Ecuador, we know virtually nothing about this shark. Only two have ever been caught, meaning its population must be very small.
Caribbean electric ray
This small, slow-moving ray has an almost-round body and grows only to 18 inches (45 cm) long. It spends its time in the surf zone and has two electric organs that run from in front of its eyes down to the rear of its body. It can generate a peak of about 14 to 37 volts of electricity that it uses to stun prey or as a defense from predators.
You can find the full list here.