Meeting Abstract
Hagfish are benthic marine craniates that have not evolved opposable jaws. Despite this, hagfish are capable of powering a “bite” that is strong enough to utilize food materials that range from marine worms to giant vertebrate carcasses. Rather than biting using an opposing pincer action, hagfish use a rasping motion of a tongue-like dental plate that is armed with keratinous teeth. The dental plate is protracted and retracted using a complex series of cartilages, muscles, and connective tissues that are collectively known as the hagfish feeding apparatus. Rigid elements of the feeding apparatus can be visualized using microCT scans, however, the organization of soft tissues can often remain more difficult to describe. In this study, we characterized the muscle and connective tissues that join and actuate the more rigid elements of the feeding apparatus through the use of traditional paraffin histological techniques. We used frontal, transverse, and parasaggital serial sections to create a three-dimensional interpretation of morphology. This analysis indicated that the cartilaginous plates of the anterior feeding apparatus are connected using thin connective tissue strap hinges that are likely formed of collagen and, in some places, cartilage. The musculature of the feeding apparatus is complex and are variously organized as antagonistic groups, that function to protract and retract the dental plates, and as muscular hydrostats that are used to provide structural support and stabilize the various rigid cartilaginous plates during movement.
