Pacific hagfish are a member of one of the most primitive craniate groups. Pacific hagfish have changed little over the past 330 million years, and closely resemble the first craniates. The evolutionary path leading to Homo sapiens probably diverged from hagfish approximately 530 million years ago. Hagfish can go several months without eating. One adult Pacific hagfish can fill a seven-liter bucket with slime in minutes.
A system of sensory organs resembling taste buds, called Schreiner organs, are found throughout the epidermis. The distribution of these organs is more extensive than taste buds in nearly any vertebrate, giving hagfish the ability to sense prey in dark and muddy habitats. This sensory system has no direct homologue in vertebrates and seems specific to hagfish. Hagfish also have well-developed nasal organs used in olfaction.
Perception Channels: chemical
Pacific hagfish remain common throughout their range.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: no special status
Pacific hagfish hatch from an egg in fully functional form without any intermediate larval stage. Determining the sex of Pacific hagfish below 35 cm in length is difficult as a copulatory organ is absent. Despite over a century of searching, only 200 fertilized eggs of Eptatretus stoutii have been found in Monterey Bay, California.
There are no negative impacts of Pacific hagfish on humans.
In Korea, approximately 5 million pounds of Pacific hagfish meat is consumed yearly, and in many countries the skin is commonly processed into "eelskin" accessories such as purses, wallets, and boots. Hagfish are sometimes found in public aquariums, and their very low metabolic rate is of specific research interest.
Positive Impacts: food ; body parts are source of valuable material; research and education
Pacific hagfish are crucial for eliminating dead and dying organsims, and the effect of large-scale removal on the ecosystem could be significant as hagfish are important for recycling nutrients.
Ecosystem Impact: biodegradation ; parasite
Pacific hagfish have two pair of primitive, yet effective, rasps on the tongue used primarily for grasping. After establishing a firm hold on a food source, the hagfish ties and unties a knot within its own body to generate a ripping force. Pacific hagfish feed on a variety of dead or dying organisms, including fish and mammals, but also probably include marine invertebrates in their diet. Male hagfish may eat hagfish eggs.
Animal Foods: mammals; fish; eggs; carrion ; aquatic or marine worms; other marine invertebrates
Primary Diet: carnivore (Scavenger )
Eptatretus stoutii (Pacific hagfish) are found in cold marine waters of the antitropical north and south Pacific Ocean on muddy sea floors.
Biogeographic Regions: pacific ocean (Native )
Pacific hagfish are found typically on muddy bottoms to depths of 633 meters, but can also be found occasionally on rocky bottoms. They are more common at shallower depths, from 40 to 100 meters. Pacific hagfish may make small migrations from shallow waters in the fall into deeper water. Although this is unconfirmed, it is consistent with seasonal migrations in other hagfish.
Range depth: 16 to 633 m.
Habitat Regions: temperate ; saltwater or marine
Aquatic Biomes: benthic
Estimated life span of Pacific hagfish in the wild is 40 years, and 17 years in captivity.
Typical lifespan
Status: wild: 40 (high) years.
Typical lifespan
Status: captivity: 17 (high) years.
Pacific hagfish resemble lampreys, being long, tubular, and pinkish grey in color. They lack fins, except for a primitive tail fin that proves useless for propulsion. Their eyes are small and reduced, but Pacific hagfish have a good sense of smell and touch. Their mouth contains a ring of short and sensitive tentacles. Hagfish do not have true jaws, but instead have two pair of rasps on the tongue used for pulling and tearing. Large slime glands run the length of their body near the degenerate lateral line. Hagfish have a partial skull and cartilagenous skeleton. They are from 30 to 63.5 cm in length and from 0.8 to 1.4 kg. Females are typically larger than males.
Range mass: 0.8 to 1.4 kg.
Range length: 30.48 to 63.5 cm.
Other Physical Features: ectothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Pacific hagfish produce large amounts of mucilaginous slime, and can tie and untie knots in their body to evade predators. The primary predators of Pacific hagfish are harbor seals (Phoca vitulina) and humans. They have also been found in the stomachs of sablefish (Anoplopoma fimbria).
Known Predators:
Hagfish reproduction is poorly understood, but evidence has been found indicating sequential hermaphroditic periods thought to arise from population pressures.
Sexes are separate, but hermaphroditic adults can be found. No specific spawning season has been identified as males and females are found at various maturation stages throughout the year. Some females have been found with distinctly separate egg batches in them. Smaller sized egg batches do not develop further until the larger batch has completed development. From 20 to 30 eggs are usually deposited at a time. Eggs have been found at depths of 15 to 25 meters. Age is difficult to determine, as hagfish have a cartilagenous skeleton.
Breeding interval: Breeding intervals are unknown, but there is some evidence that individuals breed once yearly.
Breeding season: There is no evidence of a breeding season.
Range number of offspring: 20 to 30.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sequential hermaphrodite; sexual ; oviparous
Pacific hagfish hatch into fully functional, small hagfish. There is no parental involvement after egg-laying.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female)
