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

lancetfish Lancetfishes are large oceanic predatory 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 widely di ...

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. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

and a weight of . It is often called the cannibal fish because numerous individuals have been caught after having devoured other lancetfish.

Habitat and ecosystem

Habitat

''A. ferox'' lives in deep-water oceans in the Western and Eastern Pacific from the Aleutian Islands to Chile and the Western Atlantic from the Gulf of Maine to the Gulf of Mexico, including the Caribbean Sea, and the Eastern Atlantic, Indian Ocean, Northwest Atlantic, and the China Sea. The ''A. ferox'' can also be found as far north as Russia. Due to the range of habitat the ''A. ferox'' can be found in, it can be caught with fisheries that are catching tuna. The daily vertical migrations from the

epipelagic The photic zone, 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 proc ...

all the way down to the

mesopelagic The mesopelagic zone (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, and begins ...

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 bathypelagic ...

zones are taken by the ''A. ferox'' in order 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 language, Hawaiian , a name also used there for the closel ...

opah Opahs, also commonly known as moonfish, sunfish (not to be confused with Molidae), kingfish, redfin ocean pan are large, colorful, deep-bodied pelagic lampriform fishes comprising the small family Lampridae (also spelled Lamprididae). The famil ...

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 true seals, and share with them external ears (pinnae), relatively lon ...

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 Lamnidae, mackerel shark found in the northern Pacific ocean. As an apex predator, the salmon shark feeds on salmon, squid, sablefish, and herring. It is known for its ability to maintain stom ...

. The predators are known to change for ''A. ferox'' depending on the region of the ocean it is inhabiting.

Effect on ecosystem

''A. ferox'' is known for its predatory and prey behaviors in the south-western and central-western Pacific Ocean. In these regions of the Pacific Ocean, there have been studies done on the effects this species 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 located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

of ''A. ferox'' 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 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 prey’s trunk muscles to stop the prey struggling. The teeth are not used for chewing otherwise.

Diet

The main diet of ''A. ferox'' can vary depending on the area it inhabits. There have been studies done that show the diet variation along with studies that show there is no diet variation. ''A. ferox'' is known to eat from 98 different prey families and even man made materials, like plastics, that find their way into the ocean. ''A. ferox'' is known as a migratory species as well as a cannibalistic one. ''A. ferox'' is known to travel down to as far as down in order to hunt. A study done in Suruga Bay, Japan explored the contents of the stomach of various ''A. ferox'' that had washed ashore and found that along with indigestible materials, there were species of sea life that were found at the surface, middle, and deep sea layers. This study showed how the ''A. ferox'' is a deep sea diving species that can easily migrate between the different layers of the sea. ''A. ferox'' is referred to as the cannibal fish, due to its conspecific predation habits. the extent of cannibalism depended on the availability of non-conspecific prey. These patterns range from 0–45.5% in frequency and depend on the availability and ease of finding other prey but ultimately make up a substantial part of the diet of ''A. ferox''. Size is an influencing factor as small lancetfish will not turn to cannibalism as quickly as larger fish.

Reproduction

The fish are simultaneous

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 Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...

s, meaning 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 an absence of a pair of diverticulae in the female reproductive section, which in other hermaphrodites is used for

spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...

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 Long line or longline may refer to: *''Long Line'', an album by Peter Wolf *Long line (topology), or Alexandroff line, a topological space *Long line (telecommunications), a transmission line in a long-distance communications network *Longline fish ...

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.