The deepsea lizardfish, ''Bathysaurus ferox'', is an
aulopiform of 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 ...
Bathysauridae, found in tropical and subtropical seas across the world. The deepsea lizardfish should not be confused with the true or "typical" lizardfishes of the related family
Synodontidae.
Taxonomy
Deepsea lizardfishes were first described in 1878 by British zoologist
Albert Günther
Albert Karl Ludwig Gotthilf Günther Fellow of the Royal Society, FRS, also Albert Charles Lewis Gotthilf Günther (3 October 1830 – 1 February 1914), was a German-born British zoologist, ichthyologist, and herpetologist. Günther is ranked th ...
, who created the generic name from ancient Greek word elements “''báthos''” and “''saûros''” meaning “lizard of the depths”. Previously recognized in the
synodontidae, in 1996, Robert Karl Johnson et al. showed its relationships outside synodontidae, in its own family in the suborder Giganturoidei.
At the beginning of the century, ''Bathysaurus ferox'' larvae were thought to be a distinct species called ''Macristium chavesi''. Johnson gave evidence of the synonymy of the two species.
Appearance


Deep-sea lizardfish resemble shallow-water
lizardfishes, as reflected in their common names. Adults reach over 70 cm in length, and have a slender,
cylindrical
A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base.
A cylinder may also be defined as an in ...
body. Their lizard-like bony head is flattened, unlike in most fishes, and an enormous mouth is filled with multiple series of long, sharp and needle like
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, te ...
for piercing and trapping prey. ''Bathysaurus ferox'' are whitish, grey or brown in color, and are covered in tough scales, which are enlarged along the
lateral line. The large, well developed eyes, with large
pupil
The pupil is a black hole located in the center of the iris of the eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company. It appears black ...
s, are evidence of the importance of vision for prey detection. Although residual sunlight does not penetrate the depths inhabited by deep-sea lizardfish, their eyes aid in detecting distinct sources of residual or
bioluminescent
Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...
light. Deep-sea lizardfish have been known to have an expansive liver constituting up to 20% of total weight, serving as an energy reserve to sustain growth between sporadic feeding episodes.
Habitat
Deepsea lizardfish are typical inhabitants of the deep ocean floor. They are found circumglobally, in
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
temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
latitudes (65° N to 40° S) at depths of 600–3,500 m in the
aphotic zone
The aphotic zone (aphotic from Greek prefix + "without light") is the portion of a lake or ocean where there is little or no sunlight. It is formally defined as the depths beyond which less than 1 percent of sunlight penetrates. Above the aphot ...
, where water temperatures range between 4 and 3 °C.
The energy-poor ecosystem dictates low population densities. Along the
Mid-Atlantic Bight
The Mid-Atlantic Bight is a coastal region running from Massachusetts to North Carolina. It contains the New York Bight. It is separated from the South Atlantic Bight by Cape Hatteras to the south and the Gulf of Maine to the north by Cape Cod
...
, a density of 0-8 fish per 25 x 10
3 m
2 has been reported.
Feeding habits

Deepsea lizardfish are one of the world's deepest living
apex predator
An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own.
Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic le ...
s, and will not hesitate to eat anything they meet, including their own kind. They are predominantly
piscivore
A piscivore () is a carnivorous animal that eats primarily fish. The name ''piscivore'' is derived . Piscivore is equivalent to the Greek-derived word ichthyophage, both of which mean "fish eater". Fish were the diet of early tetrapod evoluti ...
s, hunting deep-dwelling
demersal
The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a laye ...
and
bathypelagic
The bathypelagic zone or bathyal zone (from Greek βαθύς (bathýs), deep) is the part of the open ocean that extends from a depth of below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below. The bathypelag ...
fishes. Occasionally, they also feed on
crustaceans
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 gr ...
and
molluscs
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...
, as well as on dead fish drifting down from above.
Most of the time, the deepsea lizardfish maintains a motionless stance on the substrate, with head and fore-body raised, waiting for prey.
Being well equipped to pursue and devour whole prey, it captures it by lunging forward in a sudden rapid burst, accompanied by a snap of its trap-like jaws.
Conservation
Although they are common inhabitants of the ocean floor, these deep-sea fish are considered a conservation concern.
Reproduction
Deepsea lizardfish are
hermaphrodite
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes.
Many taxonomic groups of animals (mostly invertebrates) do not have ...
s, bearing both male and female
sex organ
A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, ...
s, thought to be an adaptation to low population densities. Mature gonads found in samples from November to January off the coast of Virginia show that their reproduction is synchronous, a means of maximizing breeding population densities without increasing the size of the feeding population. Mean fecundity rates of around 32,000 ova per fish were observed for eight specimens. Not much is known about their mating habits; however, larval deepsea lizardfish have been recorded at the surface of the
ocean
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...
.
References
*
* Tony Ayling & Geoffrey Cox, ''Collins Guide to the Sea Fishes of New Zealand'', (William Collins Publishers Ltd, Auckland, New Zealand 1982)
animalpicturesarchive
{{Taxonbar, from=Q5084535
Aulopiformes
Fish described in 1878
Taxa named by Albert Günther