Sea dragon was the Safeholdian equivalent of a terrestrial whale.
There are several species of sea dragon, the largest of which grow to a body length of approximately fifty feet. Like the whale, sea dragons are mammalian. They are insulated against deep oceanic temperatures by thick layers of blubber and are krill-eaters.
They reproduce much more rapidly than whales, however, and are the principal food source for doomwhales and large, deepwater krakens. Most species of sea dragon produce the equivalent of sperm oil and spermaceti. A large sea dragon will yield as much as four hundred gallons of oil. (MTAT)