The slippery Myxiniforme, also known as slime eel, hagfish, Myxini, or parasitic fish, has an interesting defense mechanism. These creatures seem to have evolved to use their slime to clog the gills of predators in less than a second and use it as a defense mechanism.
Myxini are considered the slimmest animals on the planet, capable of producing mucus that expands to 10,000 times its size in 0.4 seconds. Recorded videos show how effective the sticky substance this fish produces at repelling predators. A particularly good example is when a shark approaching for the kill instantly gives up its victim, possibly with a taste of regret mixed with the sulfur ball stuck in its mouth.
The sticky substance produced by this fish is formed when seawater interacts with two different components secreted by the mucus glands. These include mucin vesicles that swell and burst rapidly in seawater, forming a floppy network of mucus filaments and a type of fiber-rich filament called an intermediate filament (IF).
These individual IF threads are only 12 nanometers wide, but can be up to 15 centimeters in length. They are arranged in thread-like bundles called hanks, made up of layers of conical loops.
To unravel the mystery of Myxini slime and how it exploded into water so quickly in a 2019 paper, researchers took a closer look at how thread cells behave when in contact with seawater. They found that the freckles begin to dissolve within the time frame of a predator’s attack (between 100 and 400 milliseconds), and that this can happen even faster if the skein is attached to a surface such as the predator’s mouth.
The skeins can expand up to 10,000 times their original size during this time, forming a web of threads that mucus vesicles can clump together to form a truly irritating sticky ball that invades the gills. It triggers this transformation, as seawater dissolves the protein glue that holds the bundles together, releasing elastic energy stores.
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