Meeting Abstract
Hagfish use a poorly understood feeding apparatus that includes a protractible dental plate capable of rasping chunks of tissue for ingestion. This feeding motion is accomplished through activity of a muscular hydrostat that is used to manipulate a tooth-bearing cartilaginous basal plate. In this study, we characterize the underlying functional mechanism by comparing the muscle and connective tissue fiber organizations in the feeding apparatuses of Gulf (Eptatretus springeri) and Pacific (Eptatretus stoutii) hagfishes. We characterized the morphology of the feeding apparatuses in four Gulf and five Pacific hagfishes by using standard paraffin histological techniques. The specimens were fixed in buffered formalin, serial sections of eight-micron thickness were taken, and tissues were differentiated using Milligan Trichrome stain. We used light microscopy to examine the internal muscle and connective tissue fiber organization in order to create a three-dimensional visualization of the hagfish feeding apparatus. Our interpretation of this visualization indicates that in both species the bulk of the feeding apparatus musculature aids in retraction and hydrostatic support of the tooth plate. A comparatively smaller ventral portion is used in protraction. Preliminary results of our morphological analyses suggest that there is no significant difference in the size of the feeding apparatuses when corrected for body size differences between the two species. Within the genus Eptatretus the morphology of the feeding mechanism seems to be quite conserved. We are engaged in expanding our morphological descriptions of other hagfish feeding apparatuses, especially those of the genus Myxine, in order to assess general hagfish morphological diversity.
