title: Hagfish slime and mucin flow properties and their implications for defense.
abstract: When hagfish (Myxinidae) are attacked by predators, they form a dilute, elastic, and cohesive defensive slime made of mucins and protein threads. In this study we propose a link between flow behavior and defense mechanism of hagfish slime. Oscillatory rheological measurements reveal that hagfish slime forms viscoelastic networks at low concentrations. Mucins alone did not contribute viscoelasticity, however in shear flow, viscosity was observed. The unidirectional flow, experienced by hagfish slime during suction feeding by predators, was mimicked with extensional rheology. Elongational stresses were found to increase mucin viscosity. The resulting higher resistance to flow could support clogging of the attacker's gills. Shear flow in contrast decreases the slime viscosity by mucin aggregation and leads to a collapse of the slime network. Hagfish may benefit from this collapse when trapped in their own slime and facing suffocation by tying a sliding knot with their body to shear off the slime. This removal could be facilitated by the apparent shear thinning behavior of the slime. Therefore hagfish slime, thickening in elongation and thinning in shear, presents a sophisticated natural high water content gel with flow properties that may be beneficial for both, defense and escape.
authors.affiliation: Department of Health Science and Technology, ETH Zürich, 8092 Zürich, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Böni
authors.affiliation: Department of Health Science and Technology, ETH Zürich, 8092 Zürich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Fischer
authors.affiliation: Department of Health Science and Technology, ETH Zürich, 8092 Zürich, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Böcker
authors.affiliation: Department of Health Science and Technology, ETH Zürich, 8092 Zürich, Switzerland.
authors.forename: Simon
authors.initials: S
authors.lastname: Kuster
authors.affiliation: Department of Materials, ETH Zürich, 8093 Zürich, Switzerland.
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Rühs
mesh_terms: D000818:Animals; D004548:Elasticity; D005880:Gills / Q000187:drug effects; D006196:Hagfishes / Q000378:metabolism / Q000502:physiology*; D009077:Mucins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D011235:Predatory Behavior; D014783:Viscosity
chemical_list: D009077:Mucins