''Notothenia neglecta'', the yellowbelly rockcod, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

, belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Nototheniidae : ''In some scientific literature, the term "cod icefish" is used to identify members of this family. This should not be confused with the term "icefish," which refers to the "white-blooded" fishes of the family Channichthyidae. See Icefish (disam ...

, the notothens or cod icefishes. It is found in the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the world ocean, generally taken to be south of 60th parallel south, 60° S latitude and encircling Antarctica. With a size of , it is the seco ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. They are

omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

, and are found in both

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 the Ancient Greek word (), meaning "the depths". ...

and

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

regions of the ocean. Their diet includes

krill Krill ''(Euphausiids)'' (: krill) are small and exclusively marine crustaceans of the order (biology), order Euphausiacea, found in all of the world's oceans. The name "krill" comes from the Norwegian language, Norwegian word ', meaning "small ...

bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

, and

gastropods Gastropods (), commonly known as slugs and snails, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and from the land. Ther ...

. They have evolved unique behaviors and morphological features in order to thrive in the cold and harsh Antarctic climate. ''N. neglecta'' is also commercially fished, although not in high numbers.

Taxonomy

''Notothenia neglecta'' was first formally described in 1951 by the Swedish

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

with the type locality being given as

Deception Island Deception Island is in the South Shetland Islands close to the Antarctic Peninsula with a large and usually "safe" natural harbour, which is occasionally affected by the underlying active volcano. This island is the caldera of an active volc ...

South Shetland Islands The South Shetland Islands are a group of List of Antarctic and subantarctic islands, Antarctic islands located in the Drake Passage with a total area of . They lie about north of the Antarctic Peninsula, and between southwest of the n ...

. Some authorities treat this taxon as a

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of '' N. coriiceps''. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''neglecta'' means "overlooked", thought to be an allusion to this species confusion with ''N. coriiceps''.

Anatomy and morphology

Members of ''N. neglecta'' have 3-7 dorsal spines, 37-40 dorsal soft rays, and 3-7 anal soft rays. Younger fish have a black patch located near the tip of their pectoral fin. ''N. neglecta'' vary in both size and weight. Sampled ''N. neglecta'' typically measure between in length and typically weigh between . ''Notothenia neglecta'' has

gut flora Gut microbiota, gut microbiome, or gut flora are the microorganisms, including bacteria, archaea, fungi, and viruses, that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the g ...

composed almost exclusively of the bacteria ''

Vibrio ''Vibrio'' is a genus of Gram-negative bacteria, which have a characteristic curved-rod (comma) shape, several species of which can cause foodborne infection or soft-tissue infection called Vibriosis. Infection is commonly associated with eati ...

'', reflective of the ability of ''N. neglecta'' to tolerate high saline conditions and frequent ingestion of

Antarctic krill Antarctic krill (''Euphausia superba'') is a species of krill found in the Antarctica, Antarctic waters of the Southern Ocean. It is a small, swimming crustacean that lives in large schools, called swarms, sometimes reaching densities of 10,000� ...

, which is composed of high amounts of

chitin Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cell ...

. ''Vibrio'' in ''N. neglecta'' may also play a role in

osmoregulation Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration ...

via regulation of sodium ions. ''N. neglecta'' possess an inflammatory response pathway that has made the fish suitable for the cold Antarctic environment. Additionally, ''N. neglecta'' synthesizes eight

antifreeze protein Antifreeze proteins (AFPs) or ice structuring proteins refer to a class of polypeptides produced by certain animals, plants, fungi and bacteria that permit their survival in temperatures below the freezing point of water. AFPs bind to small ...

s to combat the freezing temperatures of the environment.

Distribution and habitat

''Notothenia neglecta'' is an Antarctic fish species that typically lives at a depth of , but has also been found living a depths from . Young ''N. neglecta'' are typically found at depths of , and adults are typically found in deeper water. In the Antarctic, they have been found in

Antarctic peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martin in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctica. ...

waters,

South Georgia Island South Georgia is an island in the Atlantic Ocean, South Atlantic Ocean that is part of the British Overseas Territories, British Overseas Territory of South Georgia and the South Sandwich Islands. It lies around east of the Falkland Islands. ...

, and

Peter I Island Peter I Island () is an uninhabited volcanic island in the Bellingshausen Sea, from continental Antarctica. It is territorial claims in Antarctica, claimed as a Dependent territory, dependency of Norway and, along with Bouvet Island and Queen Ma ...

. It is the dominant fish species in Potter Cove, King George Island, and the South Shetland Islands. ''N. neglecta'' display a wide and diverse diet. They are an omnivorous species, and feed on both

and

species. Benthic ''N. neglecta'' most commonly feed on krill, but in the summertime, heavily prey on

salp A salp (: salps, also known colloquially as “sea grape”) or salpa (: salpae or salpas) is a barrel-shaped, Plankton, planktonic tunicate in the family Salpidae. The salp moves by contracting its gelatinous body in order to pump water thro ...

s. ''N. neglecta'' has also been shown to feed on a variety of isopods, amphipods, algae, and bivalves.

Behavior

''N. neglecta'' engage in unique behaviors that have allowed them to thrive in the harsh Antarctic climate. They typically feed at night, which may be attributed to avoidance of larger predators who tend to feed during the day, and also because many of the creatures they feed on are nocturnal. Aggressiveness in feeding has been linked to photoperiod, or availability of light throughout the day. They are less aggressive in their pursuit of prey during the day, but at night, the highest level of aggressiveness and pursuit are observed. ''N. neglecta'' has also demonstrated evidence of social hierarchy. Scientists have observed fish become less reactive to availability of prey in the presence of another member of their species. This suggests that these less reactive members may be the less dominant members of their groups. Once the other fish were removed from the environment, the original member would hunt prey as normal. ''N. neglecta'' only spawns once a year. Females usually have their first spawn between the ages of 6 and 8 years old.Froese & Luna

Notes

References

*Barrera-Oro, E. R., & Casaux, R. J. (1990). Feeding selectivity in ''Notothenia neglecta'', Nybelin, from Potter Cove, South Shetland Islands, Antarctica. ''Antarctic Science'', 2(3), 207-213. doi:10.1017/s0954102090000281 *Cormack, W. P., & Fraile, E. R. (1990). Bacterial flora of newly caught Antarctic fish ''Notothenia neglecta''. ''Polar Biology'', 10(6). doi:10.1007/bf00233688 *Donatti, L., & Fanta, E. (2002). Influence of photoperiod on visual prey detection in the Antarctic fish ''Notothenia neglecta''. ''Antarctic Science'', 14(2), 146-150. doi:10.1017/s0954102002000706 *Froese, R., & Luna, S. M. (n.d.). ''Notothenia neglecta'' summary page. Retrieved from https://www.fishbase.se/summary/58010 *Hsiao, K., Cheng, C. C., Fernandes, I. E., Detrich, H. W., & DeVries, A. L. (1990). An antifreeze glycopeptide gene from the antarctic cod ''Notothenia coriiceps neglecta'' encodes a polyprotein of high peptide copy number. Proceedings of the National Academy of Sciences, 87, 9265-9269. doi:10.1073/pnas.87.23.9265 *''Notothenia neglecta'' Nybelin, 1951. (n.d.). Retrieved from https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=642593#null *Silva, J. R., Hernadez-Blazquez, F. J., & Barbieri, R. L. (1998). Induced inflammatory process in the Antarctic fish ''Notothenia neglecta''. ''Polar Biology'', 20(3), 206-212. doi:10.1007/s003000050297 {{Taxonbar, from=Q2742972 neglecta Fish of Antarctica Taxa named by Orvar Nybelin Fish described in 1951