Sandshark

Sandsharks are a dragon in the How to Train Your Dragon book series, first described in book 12. They are aligned to the Dragon rebellion, but are considered to be one of the less fearsome rebel dragons.

A pack hunter, they have the ability to burrow through sand so fast that they give the appearance of swimming, with only their shark-like fin visible on the beach. They fire small darts from their mouths. One dart will cause numbness, but four or five can cause unconciousness in both humans and dragons, depending on body size.