''Alepisaurus ferox'', also known as the long snouted lancetfish, longnose lancetfish, or cannibal fish, is a species of

lancetfish Lancetfishes are large oceanic predatory ray-finned fishes in the genus ''Alepisaurus'' ("scaleless lizard") in the monogeneric family Alepisauridae. Lancetfishes grow up to in length. Very little is known about their biology, though they are ...

found in the ocean depths down to 1,830 m (6,000 ft). This species grows to in

total length Fish measurement is the measuring of individual fish and various parts of their anatomies, for data used in many areas of ichthyology, including taxonomy and fishery biology. Overall length Standard length (SL) is the length of a fish measured f ...

and a weight of . The appellation ''cannibal fish'' stems from discoveries of partially-digested conspecifics in captured specimens.

Habitat and ecosystem

Habitat

''A. ferox'' lives in deep water oceans in the Western and Eastern Pacific, from the Aleutian Islands to Chile; the Western Atlantic, from the Gulf of Maine to the Gulf of Mexico, including the Caribbean Sea; in addition to the Northwest & Eastern Atlantic, Indian Ocean and China Sea. The longnose lancetfish can also be found as far north as Russia. This expansive geographic reach has caused for the species to be accidentally caught by some tuna fisheries. Daily vertical migrations from the

epipelagic The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological ...

all the way down to the

mesopelagic The mesopelagic zone (Greek language, Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light ...

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 bathypela ...

zones are undertaken to find food.

Predators

The known predators for ''A. ferox'' include

yellowfin tuna The yellowfin tuna (''Thunnus albacares'') is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide. Yellowfin is often marketed as ahi, from the Hawaiian , a name also used there for the closely related bigeye ...

opah The opah, also commonly known as moonfish, sunfish (not to be confused with Molidae), cowfish, kingfish, and redfin ocean pan are large, colorful, deep-bodied Pelagic zone, pelagic lampriform Fish, fishes comprising the genus ''Lampris'', of ...

fur seal Fur seals are any of nine species of pinnipeds belonging to the subfamily Arctocephalinae in the family Otariidae. They are much more closely related to sea lions than Earless seal, true seals, and share with them external ears (Pinna (anatomy ...

Pacific cod The Pacific cod (''Gadus macrocephalus)'' is a species of ray-finned fish in the family Gadidae. It is a bottom-dwelling fish found in the northern Pacific Ocean, mainly on the continental shelf and upper slopes, to depths of about . It can grow ...

, and

salmon shark The salmon shark (''Lamna ditropis'') is a species of mackerel shark found in the northern Pacific ocean. Similar to other mackerel sharks, salmon sharks have a thunniform body type. As an apex predator, the salmon shark feeds on salmon, squid, s ...

. Predators are known to change depending on the ocean region.

Effect on ecosystem

''A. ferox'' is known for its predatory and prey behaviors in the south-western and central-western Pacific Ocean. In such regions, studies have been conducted to investigate the effects the longnose lancetfish has on the surrounding ecosystems—and whether those impacts are negative or positive for said ecosystems. When ''A. ferox'' was removed from these regions of the Pacific Ocean, there was a negative effect on the ecosystems that showed the importance of this species as both a predatory and prey type.

Characteristics and behavior

Appearance

The

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

has about three rays strongly exerted, beginning with the third or fourth ray. It is known to have a large mouth with two fangs. It is generally pale, iridescent, and dark around the dorsal fin; all of its fins are either dark brown or black. The

stomach The stomach is a muscular, hollow organ in the upper gastrointestinal tract of Human, humans and many other animals, including several invertebrates. The Ancient Greek name for the stomach is ''gaster'' which is used as ''gastric'' in medical t ...

of ''A. ferox'' is similar to that of the other species in the suborder of Alepisauroidea. The gut of the ''A. ferox'' is a large, blind-sac that also has a very unique biological response to food. The stomach will store food in the stomach and slowly digest the contents, allowing for a more in depth understanding of the exact diet the ''A. ferox'' have. FMIB 47155 Plagyodus ferox

The large, sharp teeth of the lancetfish have two functions; breaking apart organisms too large to swallow whole and cutting trunk muscles to inhibit struggling. The teeth are not used for chewing otherwise.

Diet

Longnose lancetfish diet varies depending on its inhabited area. Studies of diet variation have produced inconsistent results. They are known to prey on 98 component families; individuals may even consume man made materials, such as plastic. The longnose lancetfish is a migratory predator. It is known to travel to a depth of in order to hunt. A study in Suruga Bay, Japan, investigated the stomach contents of various specimens that had washed ashore and found, along with indigestible materials, traces of marine species of the

photic The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological ...

and

aphotic 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 ...

zones. This study showed that the longnose lancetfish is a deep sea diving species capable of migrating across different sea depths. As aforementioned, the longnose lancetfish is referred to as the ''cannibal fish'' due to its conspecific predation habits. The extent of cannibalistic behavior depends on the availability of non-conspecific prey, with frequency of these patterns ranging from 0 to 45.5%. Such is contingent upon the availability and ease of finding other prey. Size is an influencing factor; small lancetfish will not resort to cannibalism as quickly as larger fish.

Reproduction

The fish are

hermaphroditic A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

: they have both male and female reproductive parts at the same time. Unlike other hermaphroditic fishes, ''A. ferox'' has two distinct testicular lobes that are independent from the ovarian region. This species also has an absence of a pair of diverticulae in the female reproductive section, which in other hermaphrodites is used for

spermatophore A spermatophore, from Ancient Greek σπέρμα (''spérma''), meaning "seed", and -φόρος (''-phóros''), meaning "bearing", or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especiall ...

uptake.

Human impact

Plastic consumption

Plastic is ingested by approximately 30% of all ''A. ferox''. Macroplastic fragments and rope fragments were the most commonly found plastic in the stomach contents with white and clear colored plastics seeming to be favored.

Bycatch

''A. ferox'' is commonly caught as

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

for longline fisheries and is never the intended target. In the Philippines, studies of longline tuna fisheries revealed that they usually caught more ''A. ferox'' than any tuna. ''A. ferox'' also accounts for 2% of all bycatch by circle and j hook longline fisheries in the Bay of Bengal. Survival of being bycatch in these types of nets is low — only one third of ''A. ferox'' survive.

References

External links

A fish with a face that horror movie fans would love surfaces off Island
{{Taxonbar, from=Q621223 Cosmopolitan fish Alepisauridae Fish described in 1833 Fish of Aruba Marine fish of Nicaragua Taxa named by Richard Thomas Lowe