Their sliminess and unique dining habits have led to a negative reputation for the hagfish, but they’re actually an important part of the ocean ecosystem.
Hagfish live in burrows on the sea floor and can be found as deep as 5,600 feet. They are referred to as “living fossils” because they closely resemble fossils of their 300 million-year-old ancestors. However, this doesn’t mean the hagfish is done evolving—they’ve developed strategic physical features that are still successful today!
Hagfish prey on small invertebrates, as well as scavenge dead and dying fish. Hagfish have an interesting way of feeding–they slither inside dead fish and eat them from the inside out. They perform an important ecological function by cleaning and recycling dead animals from the sea floor. Due to their slow metabolism, hagfish can even survive several months without eating. Hagfish can also absorb nutrients through their skin.
Hagfish are the only animals that have a skull but no spine. However, this skull is made up of cartilage instead of bone, so they are extremely flexible. The hagfish can escape the grasp of a predator by tying itself into a knot. They also have extremely soft skin that is loosely fitted to their bodies, allowing them to fit into small spaces with ease.
They are infamous for their defensive slime. When the hagfish is stressed, glands lining their bodies secrete stringy proteins that, upon contact with seawater, expand into a transparent, sticky substance. When attacked, the predator gets a mouthful of slime, while the hagfish slides away. If the hagfish gets stuck in its own slime, a “sneeze” and a knot helps it escape.
To learn more about how you can help protect unique deep-sea creatures such as the hagfish, visit aqua.org/care.