Scientific name -- Hydra thalassa
Size -- 30,000+ lbs
Diet -- large fish, whales, sailors

A terrifying sea monster with six serpent heads and a ring of barking dogs around her waist, Scylla guarded one side of the straits of Messina, between Sicily and Italy. The dogs alerted her when a ship was passing so she could seize sailors. Scylla was originally a beautiful nymph who was transformed by the jealous sorceress Circe.