Hagfish, of the class Myxini and order Myxiniformes, are eel-shaped, slime-producing marine fish. They are the only known living animals that have a skull but no vertebral column, although hagfish do have rudimentary vertebrae. Along with lampreys, hagfish are jawless; they are the sister group to jawed vertebrates, and living hagfish remain similar to hagfish from around 300 million years ago.
Hydrothermal circulation in its most general sense is the circulation of hot water. Hydrothermal circulation occurs most often in the vicinity of sources of heat within the Earth's crust. In general, this occurs near volcanic activity, but can occur in the deep crust related to the intrusion of granite, or as the result of orogeny or metamorphism.
A hydrothermal vent is a fissure on the seafloor from which geothermally heated water discharges. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart at spreading centers, ocean basins, and hotspots. Hydrothermal deposits are rocks and mineral ore deposits formed by the action of hydrothermal vents.
Riftia pachyptila, commonly known as the giant tube worm, is a marine invertebrate in the phylum Annelida related to tube worms commonly found in the intertidal and pelagic zones. R. pachyptila lives on the floor of the Pacific Ocean near hydrothermal vents, and can tolerate extremely high hydrogen sulfide levels. These worms can reach a length of 3 m, and their tubular bodies have a diameter of 4 cm (1.6 in). Ambient temperature in their natural environment ranges from 2 to 30°C.
The Gulf hagfish is the only known species with the ability to enter brine pools, or pools of extremely high salt content, unharmed. These pools resemble lakes on the ocean floor. They exist in both the Gulf of Mexico and the Mediterranean Sea. The high salt content, approximately 200 ppt compared to 35 ppt for standard seawater, creates a buoyant surface which renders oceanic submersibles unable to descend into the pool. Often, other species can be seen floating lifelessly on the surface. It is believed that the pools only support bacterial life.
The broadgilled hagfish or New Zealand hagfish is a hagfish found around New Zealand and the Chatham Islands as well as around the south and east coasts of Australia, at depths between 1 and 900 metres.
The Pacific hagfish 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.
Eptatretus is a large genus of hagfish.
Chrysomallon squamiferum, commonly known as the scaly-foot gastropod, scaly-foot snail, or sea pangolin, is a species of deep-sea hydrothermal-vent snail, a marine gastropod mollusc in the family Peltospiridae. This vent-endemic gastropod is known only from deep-sea hydrothermal vents in the Indian Ocean, where it has been found at depths of about 2,400–2,900 m (1.5–1.8 mi). C. squamiferum differs greatly from other deep-sea gastropods, even the closely related neomphalines. In 2019, it was declared endangered on the IUCN Red List, the first species to be listed as such due to risks from deep-sea mining of its vent habitat that also produce high-quality metal ores.
The Endeavor Hydrothermal Vents are a group of hydrothermal vents in the northeastern Pacific Ocean, located 260 kilometres (160 mi) southwest of Vancouver Island, British Columbia, Canada.
The inshore hagfish is a hagfish found in the Northwest Pacific, from the Sea of Korea and across eastern Japan to Taiwan. It has six pairs of gill pouches and gill apertures. These hagfish are found in the sublittoral zone. They live usually buried in the bottom mud and migrate into deeper water to spawn. The inshore hagfish is the only member of the Myxinidae family having a seasonal reproductive cycle.
Eptatretus bischoffii is a common hagfish of the genus Eptatretus. Its maximum length is 55 centimetres (22 in). It lives in a demersal, non-migratory, marine habitat with its depth range between 8–50 m. It can survive in only temperate zones. These organisms are found in the South Pacific, mainly, Chile. It is harmless to humans.
Myxine glutinosa, known as the Atlantic hagfish in North America, and often simply as the hagfish in Europe, is a species of jawless fish of the genus Myxine.
The black hagfish is a species of hagfish.
Eptatretus hexatrema, the sixgill hagfish or snotslang, is a species of marine fish in the hagfish family of order Myxiniformes. It is native to the South Atlantic Ocean and southwestern Indian Ocean.
Eptatretus polytrema, the fourteen-gill hagfish or Chilean hagfish, is a demersal and non-migratory hagfish of the genus Eptatretus. It is found in muddy and rocky bottoms of the southeastern area of the Pacific Ocean near the coast of Chile between Coquimbo and Puerto Montt, at depths between 10 and 350 m. This hagfish can reach a length of 93 cm. It is only known from a few specimens and has not been recorded since 1988.
Eptatretus minor is a bathydemersal and non-migratory hagfish of the genus Eptatretus. It is found in the deep waters of the northern area of the Gulf of Mexico between Louisiana and Florida, at depths between 300 and 470 m. This hagfish is a relatively short and stout species, reaching a maximum length of nearly 40 cm. It is only known from a few specimens.
Archidactylina is a genus of copepods that contains only the species Archidactylina myxinicola, and is the only genus in the family Archidactylinidae. It is a parasite of the gill pouches of two species of hagfish found in Japanese waters, Eptatretus okinoseanus and Myxine garmani.
The hydrothermal vent microbial community includes all unicellular organisms that live and reproduce in a chemically distinct area around hydrothermal vents. These include organisms in the microbial mat, free floating cells, or bacteria in an endosymbiotic relationship with animals. Chemolithoautotrophic bacteria derive nutrients and energy from the geological activity at Hydrothermal vents to fix carbon into organic forms. Viruses are also a part of the hydrothermal vent microbial community and their influence on the microbial ecology in these ecosystems is a burgeoning field of research.
Kemp Caldera and Kemp Seamount form a submarine volcano south of the South Sandwich Islands, in a region where several seamounts are located. The seamount rises to a depth of 80 metres (260 ft) below sea level, the caldera has a diameter of 8.3 by 6.5 kilometres and reaches a depth of 1,600 metres (5,200 ft). It was discovered in 2009 during bathymetric mapping. The caldera contains several hydrothermal vents, including white smokers and diffuse venting areas, which are settled by chemolithotrophic ecological communities. The seamount and caldera are part of the South Georgia and the South Sandwich Islands Marine Protected Area.
