The Octopoteuthidae are a
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 ...
of
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 ...
comprising two
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 ...
. The family is characterized by
tentacle
In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...
s which cease to grow after the
paralarval stage which leads to the adult having eight arms; thus, members of this family are
commonly named as octopus squids.
Description
Octopoteuthidae is considered to be closely related to the
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...
family Lepidoteuthidae (genus ''
Lepidoteuthis''), sometimes being its
sister family.
Octopus squids are
characterized by a semi-
gelatinous
Gelatin or gelatine () is a translucent, colorless, flavorless food ingredient, commonly derived from collagen taken from animal body parts. It is brittle when dry and rubbery when moist. It may also be referred to as hydrolysis, hydrolyzed col ...
body, with very long, broad fins; the fins approach the
length of the mantle in adults. These are oval in shape and muscular, with the two fins being fused towards the midline of the mantle. Their namesake feature is the lack of tentacles in adults;
paralarvae and young juveniles possess them, but they do not develop after this stage, and so the adults only have
eight arms like an
octopus
An octopus (: octopuses or octopodes) is a soft-bodied, eight-limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like oth ...
; these arms are armed with hooks. They do not have a
hectocotylus; rather, they have a "
penis
A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, urinate.
The term ''pen ...
" or terminal organ, which is "often greatly enlarged, elongate", extending well beyond the mantle's opening.
Photophores are present on the arm-tips, and these are useful in distinguishing the genera.
The family comprises two genera. A 2019 study recovered some additional species and separates ''Octopoteuthis'' into four
species group
In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...
s, though further research is needed to confirm this:
*Genus ''
Octopoteuthis'' (
spindle-shaped photophore on all arm tips; smaller bodied)
**''
Octopoteuthis danae''
**''
Octopoteuthis deletron''
**''
Octopoteuthis fenestra'' *
**''
Octopoteuthis indica''
**''
Octopoteuthis laticauda'' *
**''
Octopoteuthis leviuncus'' *
**''
Octopoteuthis longiptera'' (''
nomen dubium
In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application.
Zoology
In case of a ''nomen dubium,'' it may be impossible to determine whether a ...
'')
**''
Octopoteuthis megaptera''
**''
Octopoteuthis nielseni''
**''
Octopoteuthis rugosa''
**''
Octopoteuthis sicula'', Ruppell's octopus squid
**''Octopoteuthis sp.'' "IO" *
**''Octopoteuthis sp.'' "Giant Pacific" *
**''Octopoteuthis sp.'' "Giant Atlantic" *
*Genus ''
Taningia'' (large, oval photophore on tip of arm-pair II; larger bodied)
**''
Taningia danae'', Dana octopus squid
**''
Taningia fimbria'' *
**''
Taningia persica'' (''
taxon inquirendum'')
**''
Taningia rubea'' *
**''Taningia sp.'' IV *
**''Taningia sp.'' V *
Species recovered by the 2019 study is marked by an asterisk (*). These have not yet been accepted by various online taxonomic databases.
[
]
References
External links
Octopoteuthidae discussion forum at TONMO.comTree of Life web project: Octopoteuthidae
{{Taxonbar, from=Q1223158
Octopoteuthoidea
Cephalopod families