The abyssal grenadier, ''Coryphaenoides armatus'', is an

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 ...

fish of the genus '' Coryphaenoides'', found in all the world's oceans, at depths between . Its adult length is , although Fishbase gives lengths up to . The abyssal grenadier's body is unique in that it contains two dorsal spines and about 124 dorsal soft rays, which are the flexible jointed rays supporting a fin nearest to the back in the spinal column. It has no anal spines, but has 115 anal soft rays along its body. The head and eyes of this fish are very large, while the mouth is very small. The color of the abyssal grenadier is brown apart from the abdomen, which is bluish.

Overview

''Coryphaenoides armatus'' occurs at the deep-slope, on the upper

continental rise The continental rise is a low-relief zone of accumulated sediments that lies between the continental slope and the abyssal plain. It is a major part of the continental margin, covering around 10% of the ocean floor. Formation This geologic str ...

between 2,000 m and 4,700 m. However, they have been observed at depths between 282 m and 5180 m. This depth range is dependent on the ocean as ''C. armatus'' lives in depths between 2000 and 4800 meters in the Atlantic and Indian Oceans but are limited to nutrient-dense environments between 2000 and 43000 meters in the Pacific Ocean. Its diet changes as it matures, from benthic invertebrates such as crustaceans and holothuroids when young to

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 ...

and bathypelagic fish,

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

s and

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s when adult. The sensory specialty of ''C. armatus'' also changes over its lifecycle; juveniles are more reliant on sight than olfaction, but developed adults are considered to be olfactory specialists. Very few ripe females, and no spent individuals have been collected, and this is suggestive of this species being

semelparous Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered semelparous if it is characterized by a single reproductive episode before death, and iteroparous if it is characteri ...

. A study done on the influence of

carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...

supply in the role of temporal changes in grenadier abundance showed a direct positive correlation to amount of carrion and the population of abyssal grenadier in the eastern North Pacific.

Feeding and Hunting Behavior

''C. armatus''' diet is mainly composed of mid-water cephalopods and fishes but can also consume echinoderms. Examination of the stomach contents of specimens collected by trawling below 2,600 m deep in the Hudson Canyon showed that an important proportion of the diet of ''C. armatus'' is caught in the deep mesopelagic and bathypelagic regions. Though the diet of ''C. armatus'' largely consists of animals, these fish have been observed to opportunistically consume

phytodetritus In oceanography, phytodetritus is the organic particulate matter resulting from phytoplankton and other organic material in surface waters falling to the seabed. This process takes place almost continuously as a "marine snow" of descending particles ...

, especially in regions where phytodetritus falls are more common. This finding was supported by researchers who found a positive correlation between increased swim speed in months with increased levels of

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

nutrient enrichment via marine snow. Research studies focused on the feeding and foraging habits of ''C. armatus'' has revealed that this species follows an active foraging strategy consistent with the

optimal foraging theory Optimal foraging theory (OFT) is a behavioral ecology model that helps predict how an animal behaves when searching for food. Although obtaining food provides the animal with energy, searching for and capturing the food require both energy and t ...

. ''C. armatus'' has been observed to maintain low metabolic rates and slow aerobic activity in their foraging; these behaviors are thought to reflect a need to conserve energy due to the extreme environmental conditions and food scarcity that exists in ''C. armatus''' natural habitats. File:Coryphaenoides armatus 1.jpg, On the Davidson Seamount at 2253 meters depth File:Autonomous landers, Observing the deepest places on Earth.WebM, ''Coryphaenoides armatus'' is seen in this video describing the operation and use of an autonomous lander (RV Kaharoa) in deep sea research File:Coryphaenoides armatus2.jpg, File:Coryphaenoides armatus.jpg, Abyssal grenadier, ''Coryphaenoides armatus''

References

External links

* {{DEFAULTSORT:Abyssal Grenadier Macrouridae Articles containing video clips Cosmopolitan animals Fish described in 1875 Deep sea fish

Overview

Feeding and Hunting Behavior

See also

References

Further reading

External links