News Release

Loose skin and 'slack volume' protect hagfish from shark bites

Peer-Reviewed Publication

Chapman University

Chapman University has published new research showing how hagfishes survive an initial attack from predators before they release large volumes of slime to defend themselves. Because the slime is released after they are attacked, this defense strategy is only effective if they survive the initial bite. Results show that hagfish skin is not puncture resistant; it is both unattached and flaccid, which helps avoid internal damage from penetrating teeth.

Hagfishes are an ancient group of eel-like animals found at the bottom of the ocean. Video footage of hagfishes being attacked, lab studies of how their defensive slime functions, and the fact hagfishes are rarely found in the stomachs of other fish, suggest that fish predators are rarely successful when they attempt to eat a hagfish.

This three-minute video shows how hagfishes use slime as their defense mechanism.

"This video really was the inspiration for our entire study," said Douglas Fudge, Ph.D., associate professor of biological sciences at Chapman University and lead author on this study. "A sizable slack volume in hagfishes, combined with minimal attachment of the skin to the muscle, allows the body to slip out of harm's way even when the skin is punctured."

Researchers studied the three layers of hagfish skin to determine how they survive the initial attack. They narrowed it down to two possibilities; the hagfishes have either puncture-resistant skin or a loose and flaccid body design that makes it more difficult for teeth to penetrate. The performance of hagfish skin is notable because they lack scales that help boost puncture resistance in many fishes. Hagfishes have a subcutaneous sinus system that runs the length of their body, containing 30 percent of their blood volume. Although previous research has found evidence that this sinus system is crucial to burrowing and knot-tying, this study shows that it also plays a role in predator defense.

The study, called "Flaccid skin protects hagfishes from shark bites," was published in the Journal of the Royal Society Interface. Researchers performed skin puncture tests of 22 fish species. They also used simulated shark bites on hagfish and their closest relatives, the sea lamprey.

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Authors of the study include: Dr. Douglas Fudge of Chapman University, Sarah Boggett and Jean-Luc Stiles of the University of Guelph, and Dr. Adam P. Summers of the University of Washington.

Learn more about Dr. Fudge's research

About the Schmid College of Science and Technology

Chapman University's Schmid College of Science and Technology offers 10 undergraduate degree programs, three graduate degree programs, one Ph.D. degree and several integrated "4+1" degree programs in both basic and applied sciences. The undergraduate programs include biochemistry and molecular biology, biological sciences, chemistry, computer science, computer information systems, environmental science and policy, mathematics, mathematics and civil engineering, physics, computational and data sciences, and software engineering. The graduate programs include food science, MBA/food science joint degree, and computational and data sciences, which has both an M.S. and Ph.D. degree offering. The school also includes three Centers of Excellence in: Earth Systems Modeling and Observation; Computation, Algebra and Topology; and Complex and Hyper Complex Analysis, as well as the Institute for Quantum Studies.

About Chapman University

As an academically distinguished center of learning, Chapman University attracts extraordinary students and faculty from around the globe. Its ten schools and colleges foster a vibrant intellectual community, and provide extensive opportunities for students to learn, grow and discover alongside remarkable faculty. The University is home to some 8,000 students pursuing bachelor, master and doctoral degrees, and is alma mater to more than 40,000 alumni found throughout the United States and the world. Now celebrating its 156th year, Chapman is known for its distinguishing strengths in leadership and civic engagement, in the arts and entertainment disciplines, and in specialized sectors of technology and science. The University is comprised of its main campus in Orange, California, and the Rinker Health Science campus for graduate health science programs in Irvine, California. Visit us at http://www.chapman.edu.


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