Oegopsida is one of the four

orders Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * H ...

squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

in the

superorder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

Decapodiformes, in the

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

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

a. Together with the Myopsina, it was formerly considered to be a suborder of the order Teuthida, in which case it was known as Oegopsina. This reclassification is due to Oegopsina and Myopsina not being demonstrated to form a clade. The Oegopsida are an often pelagic squid, with some nerito-oceanic species associated with sea mounts. They consist of 24

families Family (from ) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictability, structure, and safety as ...

and 69

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

. They have these characters in common: the head is without tentacle pockets, eyes lack a corneal covering, arms and tentacle clubs may have hooks, the buccal supports are without suckers, and oviducts in females are paired. Two families, the Bathyteuthidae and Chtenopterygidae, which have features characteristic of the

Myopsida Myopsida is one of the four orders of squid. It consists of two families: the monotypic '' Australiteuthis'' and the diverse and commercially important Loliginidae (~50 species). Some taxonomists classify this taxon as a suborder of the order T ...

while retaining others common to the Oegopsina, were formerly placed in the family, but are now placed in their own order Bathyteuthida. The Oegopsida differ from the coastal Myopsida, characterised by the genus ''

Loligo ''Loligo'' is a genus of squid and one of the most representative and widely distributed groups of myopsid squid. The genus was first described by Jean Baptiste Lamarck in 1798. However, the name had been used earlier than Lamarck ( Schneider, ...

'', which have corneal coverings over the eyes and tentacle pockets, but lack hooks, have no suckers on the buccal supports, and a single oviduct. Oegopsid squid are the only decapods that lack a pocket for the tentacles. Otherwise, they share different characters with different decapod groups. Like the Bathyteuthida and Myopsida, the Oegopsida have a brachial canal, which is absent in other forms. As with the Spirulidae and Idiosepiidae, the Oegopsida lack suckers on the buccal supports, and like the Bathyteuthida, Idiosepiidae, and Spirulidae, they have no circular muscle on the suckers.

Evolution

The earliest fossils of Oegopsida are jaw fragments from the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

or early

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

of the Yezo Group in

Hokkaido is the list of islands of Japan by area, second-largest island of Japan and comprises the largest and northernmost prefectures of Japan, prefecture, making up its own list of regions of Japan, region. The Tsugaru Strait separates Hokkaidō fr ...

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 ...

. These jaw fragments are extremely large, suggesting that oegopsids could already evolve very large body sizes early on. One of these fossils was described as the genus '' Yezoteuthis'', which has been estimated to rival the modern giant squid in size. Another jaw fragment described in 2023 was found to be twice as long as a giant squid's jaws.

Taxonomy

The following taxonomic classification was found by Fernández-Álvarez ''et al''., 2021: *Order Oegopsida **Superfamily Architeuthoidea ***Family Architeuthidae ***Family Neoteuthidae **Superfamily Cranchioidea ***Family Cranchiidae ***Family

Ommastrephidae Ommastrephidae is a family (biology), family of squid containing three subfamilies, 11 genus, genera, and over 20 species. They are widely distributed globally and are extensively fished for food. One species, ''Todarodes pacificus'', comprised a ...

***Family Thysanoteuthidae **Superfamily

Chiroteuthoidea Chiroteuthoidea is a Superfamily (biology), superfamily of squid in the order Oegopsida. They are the sister group to the Pholidoteuthis, Pholidoteuthoidea. It contains the following families: * Superfamily Chiroteuthoidea ** Family Batoteuthis ...

***Family

Batoteuthidae ''Batoteuthis skolops'', the bush-club squid, is the single rare species in genus ''Batoteuthis'', which is the only genus in family (biology), family Batoteuthidae. The squid is found in Antarctic waters, and reaches a mantle (mollusc), mantle le ...

***Family Chiroteuthidae ***Family Joubiniteuthidae ***Family Magnapinnidae ***Family Mastigoteuthidae ***Family Promachoteuthidae **Superfamily Cycloteuthoidea ***Family Brachioteuthidae ***Family Cycloteuthidae **Superfamily Enoploteuthoidea ***Family Ancistrocheiridae ***Family

Enoploteuthidae Enoploteuthidae is a family of squid comprising approximately 40 species in four genera. Most species have a mantle length ranging from . Hooks are present on all arms and tentacles. The family is best known for the large array of photopho ...

***Family Lampadioteuthidae ***Family Lycoteuthidae ***Family

Pyroteuthidae Pyroteuthidae (the fire squids) is a family (biology), family of squids. The family comprises two genus, genera. Species are Diurnality, diurnally Mesopelagic zone, mesopelagic, migrating into surface waters during the night. The family is charac ...

**Superfamily Pholidoteuthoidea ***Family Pholidoteuthidae **Superfamily Octopoteuthoidea ***Family Lepidoteuthidae ***Family Octopoteuthidae **''incertae sedis'' ***Family Gonatidae ***Family Histioteuthidae ***Family

Onychoteuthidae The hooked squid, family (biology), family Onychoteuthidae, currently comprise about 20–25 species (several known from only single life stages and thus unconfirmed), in six or seven genus, genera. They range in mature mantle (mollusc), mantle l ...

***Family Psychroteuthidae ***Genus †'' Yezoteuthis''

Phylogeny

The following phylogeny was found by Fernández-Álvarez ''et al''., 2021: *

References

External links

* Squid Decapodiformes {{Squid-stub