genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
bony fish
Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...
in the family
Scombridae
The mackerel, tuna, and bonito family, Scombridae, includes many of the most important and familiar food fishes. The family consists of 51 species in 15 genera and two subfamilies. All species are in the subfamily Scombrinae, except the but ...
, and
tribe
The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...
Thunnini, also known as the tunas. ''Auxis'', commonly and collectively called the frigate tunas, is one of five genera of tunas which comprise the Thunnini tribe.
Species
There are four extant species in the genus ''Auxis'', which were formerly regarded as two polytypic species, each with two
subspecies
In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
. In 2021, the extinct species ''Auxis koreanus'' was described from the
Neogene
The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...
of
South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...
''Auxis'' can reach a length of . They have a strong, fusiform body with a sharpened head. The teeth are small and conical. The two dorsal fins are separated by a wide gap. The pectoral fins are short. They have a dark, blue-black back, the top of the head may be deep purple or almost black. The belly is whitish and without streaks or spots.
Distribution
These fishes are widespread in all tropical and subtropical seas and oceans, and both mentioned species are present in the Mediterranean Sea with their subspecies (''A. thazard thazard'' and ''A. rochei rochei).''
Ecology
''Auxis'' species are the predominant prey of pelagic gamefish off of the east coast of the United States.
As food
In
Japan
Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
the two species in the genus are collectively called , and this is also the common genus name. In
Japanese cuisine
Japanese cuisine encompasses the regional and traditional foods of Japan, which have developed through centuries of political, economic, and social changes. The traditional cuisine of Japan (Japanese language, Japanese: ) is based on rice with m ...
, these fish are processed into , a product much like , though not really used in fine-dining restaurants or as condiment, but as a fish stock ingredient at more budget type popular-dining places, e.g., noodle shops.
Although fresh fish might be eaten as
sashimi
is a Japanese cuisine, Japanese delicacy consisting of fresh raw fish or Raw meat, meat sliced into thin pieces and often eaten with soy sauce.
Origin
The word ''sashimi'' means 'pierced body', i.e., "wikt:刺身, 刺身" = ''sashimi'', whe ...
or grilled, it has a lot of dark-red meat (), so it is valued much less than the similar ' (
skipjack tuna
The skipjack tuna (''Katsuwonus pelamis'') is a perciform fish in the tuna family, Scombridae, and is the only member of the genus ''Katsuwonus''. It is also known as katsuo, arctic bonito, mushmouth, oceanic bonito, striped tuna or victor fish. ...
). And it degrades quickly so shipment out to market is limited. The frigate tuna () is considered superior between the two.
Fossil record
Fossils of ''Auxis'' have been found in the
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
of South Korea and the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Paleobiology Database /ref>