Pacific hagfish

The Pacific hagfish (Eptatretus stoutii) is a species of hagfish. It lives in the mesopelagic to abyssal Pacific Ocean, near the ocean floor. It is a jawless fish and has a body plan that resembles early Paleozoic fish. They are able to excrete prodigious amounts of slime in self-defense.

Description
The Pacific hagfish has a long, eel-like body, but is not closely related to eels. Maximum body lengths of 63 cm have been reported; typical length at maturity is around 42 cm. It is dark brown, gray or brownish red, often tinted with blue or purple. The belly is lighter and sometimes has larger white patches. It has no true fins, but there is a dorsal fin-fold. The head, as in all agnathans, does not have jaws, and the sucker-like mouth is always open, with 8 barbels around it. There are no visible eyes. Starting about one quarter of their body length from the front are 10–14 gill pores.

Hagfish have loosely fitting, slimy skins, and are notorious for their slime-production capability. When disturbed, they ooze proteins from slime glands in the skin that respond to water by becoming a slimy outer coating, expanding into a huge mass of slime. This makes the fish very unsavory to predators, and can even be used to clog the gills of predatory fish. Pacific hagfish can create large amounts of slime in just minutes. The slime is notoriously difficult to remove from fishing gear and equipment, and has led to Pacific fishermen bestowing the nickname of 'slime eel' on the species.

Hagfish also possess the unique ability to tie their bodies into knots. This adaptation becomes useful when the fish needs to remove the suffocating nature of its own slime by pulling itself through a knot. The knots also provide aid in the process of ripping apart meat.

Similar species
Eptatretus deani has its first gill pore closer to the head. Lampetra tridentata has visible eyes and 7 gill pores. Myxine limosa has gill pouches with one exterior connection.

Taxonomy
The Pacific hagfish confused scientists at first because Carl Linnaeus mistakenly classified the organism as an "intestinal worm".

Distribution and habitat
The Pacific hagfish occurs in the Northeast Pacific Ocean from southeast Alaska to Baja California, Mexico. It inhabits fine silt and clay bottoms on the continental shelves and upper slopes at depths from 16 - 966 m. The species appears to be abundant within its range.

Diet
While Pacific hagfish likely take polychaete worms and other invertebrates from the sea floor, they are also known to enter dead, dying or inhibited large fish through the mouth or the anus, and feed on their viscera.

The diet of other hagfish species includes shrimps, hermit crabs, cephalopods, brittle stars, bony fishes, sharks, birds and whale flesh, but specific information about the Pacific hagfish is lacking.

The Pacific hagfish's skin can absorb amino acids.

Reproduction
Hagfish fertilise their eggs externally after the female has laid them. On average females lay about 28 eggs, about 5 mm in diameter, which are carried around after they have been fertilised. Females will however try to stay in their burrows during this period to ensure the protection of their eggs.

Use by humans
There is a well-developed hagfish fishery on the US West Coast that mostly supplies the Asian leather-market. Hagfish-skin clothing, belts, or other accessories are advertised and sold as "yuppie leather" or "eel-skin".