Other sharks are one of the main predators of the spotted ratfish. Due to their opportunistic hunting tendencies, they feed on a variety of marine life. The spotted ratfish is much smaller in size than the other species of sharks that pursue it, such as the sixgill shark, sevengill shark, spiny dogfish and tope shark. These species of shark are larger and often seen in aquariums and captivity. While they are virtually harmless to humans, they pursue prey, such as the spotted ratfish, on a daily basis as a means of food.
Fish, such as the giant sea bass, lingcog, rockfish and Pacific halibut, are all known predators of the spotted ratfish. These fish are larger in size than the spotted ratfish, thus making the hunt easier. These large varieties of fish, particularly the Pacific halibut, tend to become active predators, attacking any species it can fool. As a flatfish, the halibut hides on the ocean floor, disguising itself until the moment is right for the strike. Most of the time, the prey did not realize it was in any danger.
Marine mammals tend to not only be larger than the spotted ratfish, but smarter as well. Sea lions, also categorized as opportunistic feeders, prey on a number of marine species, sharks, fish and crustaceans. Sea lions are also smart enough to not only hunt prey, but even take fish right off fisherman's hooks. The spotted ratfish is an easy target for such a skilled hunter as the sea lion.
The Pigeon Guillemot resides in the Pacific region, where the spotted ratfish also primarily lives. It preys on fish that have a high lipid content, meaning a high amount of fat. The spotted ratfish fulfills this quality, making it ideal prey for a bird like the Pigeon Guillemot. It tends to hunt prey close to shore or in shallow water, much like the ratfish is at night when it is hunting for its meal.