The Silkspanner is a flightless Mystery Class dragon that first appeared in Dragonvine.
Although flightless, Silkspanners can fly and glide for relatively short distances (i.e. between islands, but not across the archipelago) by weaving webbing between their three pairs of legs. With these, they are able to catch the wind currents. This leaves them somewhat vulnerable to the whims of wind direction. Additionally, they fill their stomachs with air to add some buoyancy, according to Dragons: Rise of Berk. They also demonstrated the ability to suck out the toxic component of the dragonvine plants that infect both dragons and humans in a seemingly painless process.