Geographic Range
Eptatretus stouti
(Pacific hagfish) are found in cold marine waters of the antitropical north and south
Pacific Ocean on muddy sea floors.
- Biogeographic Regions
- pacific ocean
Habitat
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.
- Habitat Regions
- temperate
- saltwater or marine
- Aquatic Biomes
- benthic
Physical Description
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.
- Other Physical Features
- ectothermic
- bilateral symmetry
- Sexual Dimorphism
- female larger
Development
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 stouti
have been found in Monterey Bay, California.
Reproduction
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.
- 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
Lifespan/Longevity
Estimated life span of Pacific hagfish in the wild is 40 years, and 17 years in captivity.
Behavior
One of the most distinguishing behaviors of hagfish is the ability to produce large
amounts of mucilaginous slime almost instantaneously. The slime is secreted as a
defense mechanism from pores that line the sides of the body. Upon contact with seawater,
the slime rapidly expands into a sticky gel that can sometimes suffocate an attacker.
Hagfish also have the ability to tie a knot in their body, and slide in and out of
the knot. This can be used to elude predators, to bury into a carcass, to gain leverage
to tear off pieces of flesh, or clean itself of slime.
- Key Behaviors
- natatorial
- motile
- colonial
Communication and Perception
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
Food Habits
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
Predation
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
).
Ecosystem Roles
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
Economic Importance for Humans: Positive
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
Economic Importance for Humans: Negative
There are no negative impacts of Pacific hagfish on humans.
Conservation Status
Pacific hagfish remain common throughout their range.
Other Comments
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.
Additional Links
Contributors
Tanya Dewey (editor), Animal Diversity Web.
Brett Schroeder (author), University of Michigan-Ann Arbor, Kevin Wehrly (editor, instructor), University of Michigan-Ann Arbor.
- Pacific Ocean
-
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- benthic
-
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- natatorial
-
specialized for swimming
- motile
-
having the capacity to move from one place to another.
- colonial
-
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
- chemical
-
uses smells or other chemicals to communicate
- carrion
-
flesh of dead animals.
- biodegradation
-
helps break down and decompose dead plants and/or animals
- parasite
-
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
- food
-
A substance that provides both nutrients and energy to a living thing.
- carnivore
-
an animal that mainly eats meat
- scavenger
-
an animal that mainly eats dead animals
References
Barnaby, R., G. Nardi, K. Cho, J. Goldman. 1995. "Trade Barriers Lifted on Hagfish Exports to Korea Earnings of Developing New England Fishery Expected to Double" (On-line). Sea Grant News Media Center. Accessed October 15, 2005 at http://www.seagrantnews.org/news/hagfish.html .
Braun, C. 1998. Schreiner Organs: A new Craniate Chemosensory Modality in Hagfishes. J Comp Neurol. , March 9;392(2): 135-163.
Broadal, A., R. Fange. 1963. The Biology of Myxine . Oslo: Grondahl & Son. Accessed October 15, 2005 at http://oceanlink.island.net/oinfo/hagfish/hagfish.html .
Fernholm, B. 1998. The Biology of Hagfishes . London: Chapman & Hall.
Finch, C. 1990. Longevity, Senescence, and the Genome . Chicago: University of Chicago Press.
King, J., G. McFarlane. 2003. Marine Fish Life History Strategies: Applications to Fishery Management. Fisheries Management & Ecology , 10: 249-264.
Martini, F. 1998. Secrets of the Slime Hag. Scientific American , October: 70-75.
McCrae, J. 1997. "Pacific Hagfish" (On-line). Oregon Developmental Species. Accessed October 15, 2005 at http://hmsc.oregonstate.edu/odfw/devfish/sp/hagfish.html .
Patzner, R. 1998. Gonads and Reproduction in Hagfishes . London: Chapman & Hall. Accessed October 15, 2005 at http://www.fishbase.org/References/FBRefSummary.cfm?ID=51361 .
Schewe, P., B. Stein, J. Riordon. 2003. "A Close Look at Hagfish Slime" (On-line). Accessed October 17, 2005 at http://www.aip.org/pnu/2003/660.html .