''Abyssobrotula galatheae'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

cusk eel The cusk-eel family, Ophidiidae, is a group of marine bony fishes in the Ophidiiformes order. The scientific name is from the Greek ''ophis'' meaning "snake", and refers to their eel-like appearance. True eels, however, diverged from other ra ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Ophidiidae The cusk-eel family, Ophidiidae, is a group of marine bony fishes in the Ophidiiformes order. The scientific name is from the Greek ''ophis'' meaning "snake", and refers to their eel-like appearance. True eels, however, diverged from other ray- ...

. It is the deepest-living

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

known; one specimen,

trawl Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different speci ...

ed from a depth of in the

Puerto Rico Trench The Puerto Rico Trench is located on the boundary between the Caribbean Sea and the Atlantic Ocean. The oceanic trench, the deepest in the Atlantic, is associated with a complex transition between the Lesser Antilles subduction zone to the sou ...

in 1970, holds the record for the deepest fish ever captured. Although generally recognized, some have suggested that the record-breaking individual might have been caught with a non-closing net (a net that is open on the way up and down into the deep) and therefore perhaps caught shallower. The first examples of this fish were misidentified by Staiger as '' Bassogigas profundissimus'', before being described as a new species by Jørgen G. Nielsen in 1977. The species name refers to the research ship HDMS ''Galathea'', which captured the first specimens during the second Galathea expedition.

Distribution and life history

Though uncommon, this species is known from all

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

and subtropical oceans. It occurs in the

abyssal The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. "Abyss" derives from the Greek word , meaning bottomless. At depths of , this zone remains in perpetual darkness. It covers 83% of the total area of the ocean a ...

and

hadal zone The hadal zone, also known as the hadopelagic zone, is the deepest region of the ocean, lying within oceanic trenches. The hadal zone ranges from around below sea level, and exists in long, narrow, topographic V-shaped depressions. The cumula ...

s below a depth of . It is bottom-dwelling in nature, although one individual has been captured from the

water column A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...

in the

Gulf of Panama The Gulf of Panama ( es, Golfo de Panamá) is a gulf of the Pacific Ocean off the southern coast of Panama, where most of eastern Panama's southern shores adjoin it. The Gulf has a maximum width of , a maximum depth of and the size of . The Pana ...

. Its diet consists of

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made ...

s and

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s, such as isopods and amphipods. Reproduction is oviparous, possibly with

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

eggs floating in a gelatinous mass as in other members of the family.

Description

This species grows to standard length. It has a short head with a downward inflection, a swollen snout and an inferior mouth. The body is soft, with a tapering

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...

and loose, transparent

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...

. Both the body and the head are covered with scales. The

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...

are small and pointed, arranged in irregular rows; the two median and single pair of basibranchial (on the most ventral

gill arch Branchial arches, or gill arches, are a series of bony "loops" present in fish, which support the gills. As gills are the primitive condition of vertebrates, all vertebrate embryos develop pharyngeal arches, though the eventual fate of these arc ...

) tooth patches are distinctive for this species. The

eyes Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and con ...

are tiny, deep-set, and hidden. They are unlikely to be functional, but there is a well-developed system of sensory

pore Pore may refer to: Biology Animal biology and microbiology * Sweat pore, an anatomical structure of the skin of humans (and other mammals) used for secretion of sweat * Hair follicle, an anatomical structure of the skin of humans (and other m ...

s on its head. The lateral line is visible only on the frontmost part of the body and lacks developed pores. Externally, ''A. galatheae'' can be distinguished from other deep-sea ophidioids by its long

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s, which contain only 10–11

fin ray Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

s each, and its flat, weakly developed opercular spine. The long

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

and anal fins contain 97–116 and 76–96 rays respectively. The pelvic fins and

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

are small and contain 2 and 8 rays respectively. The coloration is yellowish; the branchial cavity is black and the

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of meso ...

dark brown. The skeleton is well-

ossified Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...

, consistent with a benthic lifestyle; there are 18–21 precaudal

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

References

{{Taxonbar, from=Q310910 Ophidiidae Deep sea fish Fish of the Atlantic Ocean Fish of the Indian Ocean Fish of the Pacific Ocean Fish described in 1977 Taxa named by Jørgen G. Nielsen

Distribution and life history

Description

See also

References