Lancetfish

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Lancetfish

Lancetfishes are large ocean

Ocean

An ocean is a major body of Seawater, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a World Ocean that is customarily divided into several principal oceans and smaller seas....
ic predatory fishes in the genus Alepisaurus ("Scaleless lizard"), the only living genus in the family Alepisauridae.

Lancetfishes grow up to in length. Very little is known about their biology

Biology

Biology is a branch of the natural sciences concerned with the study of living organisms and their interaction with each other and their environment ....
, even though they are widely distributed in all oceans, except the polar

Polar region

Earth polar regions are the areas of the globe surrounding the geographical pole also known as Geographical zone. The North Pole and South Pole being the centers, these regions are dominated by the polar ice caps, resting respectively on the Arctic Ocean and the continent of Antarctica....
sea

SEA

See also: Sea and seasThe three-letter acronym SEA may refer to:People/organizations/businesses*Scientists and Engineers for America, a pro-science political advocacy group....
s. Specimens have been recorded as far north as Greenland

Greenland

Greenland is a member country of the Kingdom of Denmark located between the Arctic Ocean and Atlantic Oceans, east of the Canadian Arctic Archipelago....
. They are often caught as by-catch for vessels long-lining for tuna

Tuna

Tuna are several species of ocean-dwelling fish in the family Scombridae, mostly in the genus Thunnus. Tunas are fast swimmers?they have been clocked at 70 km/h ?and include several species that are warm-blooded....
.

The generic

Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
name is from Greek

Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
a- meaning "without", lepis meaning "scale", and sauros meaning "lizard".

etfishes possess a long and very high dorsal fin

Dorsal fin

A wikt:dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Its main purpose is to stabilize the animal against rolling and assist in sudden turns....
, soft-rayed from end to end, with an adipose fin behind it.

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Encyclopedia

Lancetfishes are large ocean

Ocean

Biology

Polar region

SEA

Greenland

Tuna

Genus

Greek language

Description

Lancetfishes possess a long and very high dorsal fin

Dorsal fin

Fish anatomy

The anatomy of fish is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs light more than air does....
and occupies the greater length of the back. This fin is rounded in outline, about twice as high as the fish is deep, and can be depressed into a groove along the back. The body is slender, flattened from side to side, deepest at the gill cover

Operculum

In biology, operculum has been used to describe several different anatomical features, in animals, in humans and even in plants. The following list gives some of the uses of the term:...
s, and tapers back to a slender caudal peduncle.

The mouth is wide, gaping to the back of the eye, and each jaw has two or three large fang-like teeth, in addition to numerous smaller teeth. The caudal fin is very deeply fork

Fork

As a piece of cutlery or kitchenware, a fork is a tool consisting of a handle with several narrow Tine on one end. The fork, as an eating utensil, has been a feature primarily of the West, whereas in East Asia chopsticks have been more prevalent....
ed; its upper lobe

Lobe

The term lobe generally refers to a projecting part of an object, but it can have more specific meanings.* In biology, lobe * In telecommunication, the term lobe has the following meanings: ...
is prolonged as a long filament, although most lancetfishes seem to lose this when captured. The anal fin originates under the last dorsal ray, and is deeply concave in outline. The ventral fins are about halfway between the anal and the tip of the snout, while the pectoral fins are considerably longer than the body is deep and are situated very low down on the sides. There are no scale

Scale (zoology)

In most biology nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration....
s and the fins are exceedingly fragile.

Species

There are currently only two recognised species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring....
:

Longnose lancetfish, Alepisaurus ferox Lowe, 1833
Shortnose lancetfish, Alepisaurus brevirostris Gibbs 1960.

The main difference between the two is the shape of the snout, which is long and pointed in A. ferox, and slightly shorter in A. brevirostris.

Ecology

Lancetfish have large mouths and sharp teeth, indicating a predatory mode of life. Their watery muscle is not suited to fast swimming and long pursuit, so it is likely that they are ambush predators, using their narrow body profile and silvery colouration to conceal their presence, then use their large dorsal fin to generate large acceleration, and large mouth and teeth to engulf prey before it can escape. That said, stomach content studies have revealed that they feed mainly upon plankton

Plankton

Plankton consist of any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. Plankton are defined by their ecological niche rather than their Phylogenetics or taxonomy classification....
ic crustacean

Crustacean

Crustaceans are a large group of arthropods, comprising almost 52,000 described species , and are usually treated as a subphylum . They include various familiar animals, such as crabs, lobsters, crayfish, shrimp, krill and barnacles....
s, squid

Squid

Squid are marine cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, Symmetry #Bilateral_symmetry, a mantle , and cephalopod arms....
and salp

Salp

A salp is a barrel-shaped, free-floating tunicate. It moves by contracting, thus pumping water through its gelatinous body. The salp strains the pumped water through its internal feeding filters, feeding on phytoplankton that it sieves out of the water....
s, as well as other fish. They have also been shown to be cannibalistic. They are preyed upon by opah

Opah

Opah are large, colorful, deep-bodied pelagic zone Lampriform fish comprising the small family Lampridae . There are only two living species in a single genus: Lampris ....
, shark

Shark

Sharks are a type of fish with a full Cartilage skeleton and a highly Streamlines, streaklines and pathlinesd body. They respire with the use of five to seven gill slits....
s, albacore

Albacore

The albacore, Thunnus alalunga, is a type of tuna in the family Scombridae. This species is also called albacore fish, albacore tuna, longfin, albies, pigfish, tombo ahi, binnaga, Pacific albacore, German bonito , longfin tuna, longfin tunny, or even just tuna....
, yellowfin tuna

Yellowfin tuna

The yellowfin tuna is a type of tuna found in open waters of tropical and subtropical seas worldwide. It is an epipelagic fish ranging in the top 100 m of the water column....
, and fur seal

Fur seal

Fur seals are any of nine species of pinnipeds in the Otariidae family. One species, the northern fur seal inhabits the North Pacific, while seven species in the Arctocephalus genus are found primarily in the Southern hemisphere....
s.

There are no commercial fisheries for lancetfishes. Their flesh is watery and gelatinous and, although edible would prove difficult to utilise. They are caught as bycatch by tuna fisheries, and are seen as a pest

Pest (animal)

A pest is an organism which has characteristics that are regarded by humans as injurious or unwanted. This is most often because it causes damage to agriculture through feeding on crops or parasitising livestock, such as codling moth on apples, or boll weevil on cotton....
, taking bait intended for more valuable species. Anecdotal evidence suggesting that they have an aphrodisiac

Aphrodisiac

An aphrodisiac is a substance which is used in the belief that it increases sexual desire. The name comes from Aphrodite, the Greek mythology of sensuality....
effect is likely to be an urban myth.

The tetraphyllidea

Tetraphyllidea

Tetraphyllidea is a large tapeworm order that contains some 60 genus and about 800 described species. Tetraphyllideans are remarkable for their scolex morphology , which are the most varied and morphologically complex amongst all tapeworm orders....
n tapeworm Pelichnibothrium speciosum is a significant parasite of Longnose lancetfish. It seems that the species is an intermediate or paratenic

Paratenic

In parasitology, the term paratenic describes an intermediate host which is not needed for the development of the parasite, but nonetheless serves to maintain the life cycle of the parasite....
host for the tapeworm (Scholz et al. 1998).

Reproduction

The reproductive system of lancetfish is something of a mystery. The gonad

Gonad

The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells....
s of adolescents have been shown to be hermaphroditic

Hermaphrodite

A hermaphrodite is an organism having both male and female reproductive organs. In many species, hermaphroditism is a common part of the life-cycle, enabling a form of sexual reproduction in which partners are not separated into distinct male and female types of individual....
, although there is no evidence of functional hermaphroditism in adults. They are oviparous.

Lancetfish

Description

Species

Ecology

Reproduction

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