© Baker, J.L. (2009) Marine Species of Conservation Concern in South Australia Full citation Baker, J.L. (2009) Marine Species of Conservation Concern in South Australia: Volume 1 - Bony and Cartilaginous Fishes. Report for the South Australian Working Group for Marine Species of Conservation Concern. J. Baker (consultant); Science and Conservation Division, and Coast and Marine Conservation branches of S.A. Department for Environment and Heritage (DEH); Marine and Coastal Community Network of S.A. (MCCN), and Threatened Species Network (TSN). Web version published by Reef Watch, South Australia.

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MYXINIDAE: HAGFISHES

© Author

Hagfishes (Pteraspidomorphi), along with Lampreys (Cephalaspidomorphi) are two of the four surviving classes of “fish”, the other two classes being sharks and bony fish (Edgar, 2000). Both the hagfish and lamprey classes contain few living species, and the two groups are the most primitive extant vertebrates, with definite fossil records of lampreys dating back at least 280 million years (Hardisty, 1986), and hagfishes dating back 350 million years. Hagfishes (family Myxinidae) are one of the most abundant groups of demersal fishes in some parts of the world, and are mainly found in temperate zones.
Hagfishes have a cartilaginous skeleton; a scale-less, eel-like body; a jawless mouth, and no paired fins or dorsal fin (Glover, in Gomon et al., 1994; Fernholm, 1998; Orana Wildlife Trust, 2003). Hagfish have an inefficient, paddle-like tail; degenerate eyes (which are completely covered by skin and a vestigial third eye), and a single, prominent nostril (Glover, in Gomon et al., 1994; Fernholm, 1998; Orana Wildlife Trust, 2003). The laterally-biting mouth of hagfish has barbels, and there are teeth on the tongue and one on the “palate”. Hagfish feed on invertebrates such as worms and crabs, in addition to scavenging on dead and dying fish, which they locate with their six sensory barbels. Their mouthparts take the form of two horny plates and a protrusible tongue-like structure, which they use to drag flesh into their mouth (Fernholm, 1998; Orana Wildlife Trust, 2003). Hagfish have mucus pores in 2 ventro-lateral lines, each line with about 70-200 glands containing mucus cells and thread cells (Fernholm, 1998). Hagfish have the ability to exude large volumes of mucus from the glands, as a defensive mechanism (Orana Wildlife Trust, 2003).
Hagfishes are an important prey item for marine mammals and large predatory invertebrates. Hagfish may be the only vertebrates with body fluids that are iso-osmotic with seawater (Fernholm, 1998).
Hagfish are important predators (often scavengers) of invertebrates and others, e.g., netted fishes and discards. Hagfish are used as food in Japan and South Korea, and their hides are processed into 'eel' leather in Korea (Fernholm, 1998).
Globally, a number of new species have been named during the 1990s and early 2000s, particularly from deeper continental slope waters (e.g. McMillan, 1998; Mok et al., 2001). During the mid 2000s, 72 named species from 6 genera were included in the Myxinidae family (Froese and Pauly, 2007). A single genus of hagfish has been recorded from southern Australian waters (Glover, in Gomon et al., 1994; Yearsley et al., 2006; CSIRO, 2007).
The Hagfishes can easily be distinguished from the Lampreys (Petromyzontidae) by the fact that the hagfishes have several barbels on the chin; their mouths are not disc- or funnel-like; they have only one continuous fin fold on the back and around the tail, and their eyes are not visible externally. In contrast, the lampreys have no barbels; their mouths are disc- or funnel-like; their eyes are well developed after the larval stage; and they have one or more dorsal fins separate from the caudal fin (Gulf of Maine Research Institute, 2003).

Associated taxa

Longfin Hagfish

Eptatretus longipinnis Strahan, 1975