Chiroteuthidae

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Chiroteuthidae
Chiroteuthid.png
Planctoteuthis sp.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: Oegopsida
Superfamily: Chiroteuthoidea
Family: Chiroteuthidae
Gray, 1849 [1]
Genera

Asperoteuthis
Chiroteuthis
Grimalditeuthis
Planctoteuthis
New Genus B
New Genus C

Contents

The Chiroteuthidae are a family of deep-sea squid, generally small to medium in size, rather soft and gelatinous, and slow moving. They are found in most temperate and tropical oceans, but are known primarily from the North Atlantic, North Pacific, and Indo-Pacific. The family is represented by approximately 12 species and four subspecies in four genera, two of which are monotypic. They are sometimes known collectively as whip-lash squid, but this common name is also applied to the Mastigoteuthidae, which are sometimes treated as a subfamily (Mastigoteuthinae) of Chiroteuthidae.

The monotypic genus Grimalditeuthis was once (and may still be) given its own family, Grimalditeuthidae. Generally speaking, chiroteuthids are not well represented by described specimens, because they are so often damaged during capture.

Description

Chiroteuthis imperator Chiroteuthis imperator.jpg
Chiroteuthis imperator

The Chiroteuthidae are most notable for their unique paralarval stage, known as the doratopsis [2] stage. Although morphology varies greatly within the family, the Chiroteuthidae are distinguished by their extremely elongated bodies and (in most species) tentacles; the latter may be up to four times the mantle length in Asperoteuthis acanthoderma . The head is atop an elongated neck and the brachial pillar is well-developed, the eyes are large; in some Planctoteuthis and all Chiroteuthis species, the fourth pair of arms possess both greater girth and length than the other arms. The fragile, gelatinous body is conical and the neck cylindrical; the fins range from oval to elliptical, about 50% of the mantle length. The suckers of the arms occur in two series, and those of the clubs in four (but are absent in subadult Grimalditeuthis and absent proximally in Asperoteuthis). The club is elongated and—with the exception of Planctoteuthis species—is subdivided by symmetrical, protective membranes into two or three parts.

The funnel locking apparatus is oval; its cartilage is ear-shaped with one or two projections and a central depression. In Grilmalditeuthis, the apparatus is fused (but nuchal articulation is free); in Chiroteuthis both the tragus and antitragus are present, while in Planctoteuthis, only the antitragus is present. Also absent in Planctoteuthis are the funnel valve, tentacle pads, and distal suckers on the fourth arms.

Some species (excluding Planctoteuthis) are bioluminescent, with photophores (light-producing organs) variably present on the inner surface of the ventral arms, on the ventral surface of the eyes (one to three patches or bands), on the ink sac, and near the club terminus. A number of chambers containing ammonium chloride are contained within the arms, head, and mantle. With a lower density than the surrounding seawater, the ammonium chloride helps chiroteuthids to conserve energy reserved for swimming by maintaining the body's neutral buoyancy. The eyelid sinus is indistinct, occipital folds are absent, and long stalks support the olfactory papillae. The largest species reach a mantle length of about 78 cm. Body coloration is typically beige to sepia, but Asperoteuthis acanthoderma is noted for its deep violet color.

Life history

Chiroteuthis veranyi immature.jpg
Chiroteuthis veranyi.jpg
Left: Immature specimens of Chiroteuthis veranyi : In this paralarval form, the pen is longer than the mantle and 'neck' combined
Right: A mature Chiroteuthis veranyi : This species has some of the longest tentacles in proportion to its size of any known cephalopod.

Little is known of chiroteuthid reproduction. [3] The distinctive doratopsis paralarvae are thought to remain within the first few hundred meters of the water column, where they likely feed on zooplankton and slowly undergo a marked transformation to subadults. During the doratopsis stage, the paralarval chiroteuthid possesses a greatly elongated gladius (internal shell) extending well beyond the fins; this supports a long, trailing, tail-like structure that is further adorned with—depending on the species—either a pair of large oval or heart-shaped "secondary fins", a series of small flaps running the length of the tail, or a series of oval "bulbs" made buoyant by low-density fluids. Some species' paralarvae also have eyes projecting ventrally. The elongated neck and brachial pillar are chambered, and vesicular tissue is present in the posterior end of the mantle and (in advanced stages) in the arms.

Although lost during maturation in most species, some adults (e.g., Grimalditeuthis) retain their tails. During the paralarva's transformation into a subadult, its arms also become elongated (but remain subequal in some species) along with other changes in body proportions; photophores are developed, and the paralarval club is resorbed and replaced with an adult form. Planctoteuthis species retain their paralarval clubs; together with a lack of photophores, this feature causes some authors to suggest Planctoteuthis species are actually mature doratopsids, arising from neoteny. The time frame of the doratopsis stage, including the onset or loss of specific features, is unknown.

Species

Grimalditeuthis bonplandi Grimalditeuthis bonplandi (2).jpg
Grimalditeuthis bonplandi

The species listed above with an asterisk (*) is questionable and needs further study to determine if it is a valid species or a synonym.

Related Research Articles

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<i>Grimalditeuthis</i> Genus of squids

Grimalditeuthis bonplandi is a squid named after the Grimaldi family, reigning house of Monaco. Prince Albert I of Monaco was an amateur teuthologist who pioneered the study of deep sea squids by collecting the 'precious regurgitations' of sperm whales. The specific name bonplandi refers to the French scientist Aimé Bonpland.

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<i>Liocranchia</i> Genus of squids

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<i>Asperoteuthis acanthoderma</i> Species of squid

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<i>Chiroteuthis veranii</i> Species of squid

Chiroteuthis veranii, commonly known as the long-armed squid, is a species of chiroteuthid squid. It grows to a mantle length of 12.5 cm and a total length of 130 cm.

<i>Asperoteuthis mangoldae</i> Species of mollusc

Asperoteuthis mangoldae, previously known as Asperoteuthis sp. A, is a chiroteuthid squid known only from the waters off the Hawaiian Islands. It differs from the closely related Asperoteuthis acanthoderma in lacking integumental tubercles and elongate fins. This species also possesses a characteristic curved groove in its funnel locking apparatus.

<i>Chiroteuthis</i> Genus of squids

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<i>Ornithoteuthis antillarum</i> Species of squid

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<i>Uroteuthis noctiluca</i> Species of cephalopods known as the luminous bay squid

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<span class="mw-page-title-main">Chiroteuthoidea</span>

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References

  1. ↑ Philippe Bouchet (2018). "Chiroteuthidae Gray, 1849". World Register of Marine Species. Flanders Marine Institute. Retrieved 25 February 2018.
  2. ↑ Young, Richard Edward (September 1991). "Chiroteuthid And Related Paralarvae From Hawaiian Waters". Ingenta Connect.
  3. ↑ Laptikhovsky, Fock, Piatkowski, Schwarz, Vladimir, Heino, Uwe, Richard (May 18, 2019). "Reproductive strategies of deep‑sea squid (Mastigoteuthidae, Chiroteuthidae, Batoteuthidae and Cranchiidae)".{{cite web}}: CS1 maint: multiple names: authors list (link)
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