There are more than a thousand species of sharks and rays in the world, and nearly a quarter of them are threatened with extinction, according to a new study.
That means these ancient types of fish are among the most endangered animals in the world. This word comes from a Swiss-based group called the International Union for the Conservation of Nature (IUCN), which maintains the so-called Red List of species threatened with extinction.
The group has been worried about sharks, rays and related species for more than 20 years. IUCN scientists have finally calculated the risk to these species, and published their results in the online journal, eLife.
