Derius Rhiin is a son of Dhane Rhiin and Riitatul, twin brother to Ryo. While he looks almost entirely inhuman, Derius is a standup member of the Animal Mastery world. He has pale yellow skin with white fades along his rather batlike limbs. His tall batlike ears frame soft yellow-white hair, and his eyes are stunning sea blue. He tends not to wear much clothing, though at Aakal he often is found bundled up in the winter. His abilities are not just with bats, however he is primarily a bat researcher more than a Dragon Breeder. The fact that he can sense and locate dragons tipped him off that this cavern would be ideal for smaller, lithe dragons.

The cavern is entirely natural, with a few small workstations built into it in strategic locations. With those in place, Derius can view most pools of water for activity. Those who have the bravery to dare enter this bat cavern will be welcomed by Derius, as he doesn't have much time to devote to raising huge dragons. Therefore, individuals wishing to pair with a Sea dragonet from this breeding house must have their own location big enough and with the proper training to take care of a Sea dragon. Derius does not have the reputation of a callous breeder, but he is known to refuse applicants based upon their Land Holdings. Experienced Dragon masters or Breeders only!

Few dragons hatch from these coves every season, perhaps 2 or 3. Derius purposefully keeps the numbers low - often selling off young dragonets or abandoning certain less-likely eggs to the sea. The dragons that hatch in these caverns are often rather small, but tend to be intelligent and have sonic abilities beyond their normal kin. Their coloration tends toward a muddy brown, with bright blues occasionally, and mottled paler patterns on back and fins.