Hagfish predatory behaviour and slime defence mechanism

Abstract

Hagfishes (Myxinidae), a family of jawless marine pre-vertebrates, hold a unique evolutionary position, sharing a joint ancestor with the entire vertebrate lineage. They are thought to fulfil primarily the ecological niche of scavengers in the deep ocean. However, we present new footage from baited video cameras that captured images of hagfishes actively preying on other fish. Video images also revealed that hagfishes are able to choke their would-be predators with gill-clogging slime. This is the first time that predatory behaviour has been witnessed in this family, and also demonstrates the instantaneous effectiveness of hagfish slime to deter fish predators. These observations suggest that the functional adaptations and ecological role of hagfishes, past and present, might be far more diverse than previously assumed. We propose that the enduring success of this oldest extant family of fishes over 300 million years could largely be due to their unique combination of functional traits.

Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

“…They have a very special and complex jawless feeding apparatus, and the two pairs of keratinous teeth are anchored to dental plates, a bilaterally folding, paired series of cartilages, seen in Fig. 42b [214]. The most startling feature is that the hagfishes, when threatened or provoked, are able to excrete surprising quantities of slime which has keratin IFs bundles (slime threads) in a woven structure holding the slime (indicated by the arrow in Fig.…”

“…chokes the predators with this gill-clogging slime [214], shown in Fig. 42d and e. A hagfish (Eptatretus cirrhatus) immediately produces a large amount of slime into the mouth of a shark as the shark is trying to eat it; thus, not being able to remove the slime, the shark has to release the hagfish.…”

“…44) show that threads in seawater exhibit a low initial stiffness (6 MPa), [213]. (b) Head of the Broadgilled hagfish with keratinous teeth on dental plate [214]; (c) hagfish slime and the slime threads, showing a chaotic woven structure that holds the sheets of slime together (indicated by a yellow arrow) [215]; hagfish slime function as a defense against gill-breathing predator: (d) a seal shark (Dalatias licha) is trying to bite and swallow the hagfish (Eptatretus cirrhatus), but the hagfish projects jets of slime (arrows) into the predator's mouth. The slime secretion took less than 0.4 s. (e) Choked, the predator releases the hagfishes and gags in an attempt to remove slime from its mouth and gill chamber [214].…”

Models of random knots

“…Finally, knots form at random in many objects of everyday practice, from extension cords, ropes, and garden hoses (Raymer and Smith 2007) to umbilical cords (Goriely 2005;Hershkovitz et al 2001) and eels (Zintzen et al 2011). …”

Hagfish Houdinis: biomechanics and behavior of squeezing through small openings

“…Although it was long believed that hagfishes are mostly sedentary animals, it has more recently come to light that they can be active scavengers and hunters that rely on elaborate locomotor and behavioral repertoires (Zintzen et al, 2011;Lim and Winegard, 2015). Hagfishes are burrowers (Gustafson, 1935;Strahan, 1963;Fernholm, 1974) and anguilliform-mode swimmers (Adam, 1960), and they are capable of tying themselves into knots (Adam, 1960;Clark et al, 2016).…”