Overview

Brief Summary

Introduction

Chiroteuthids are small to medium in size (up to 78 cm ML), rather gelatinous, slow moving, deep-sea squids usually with elongate necks and slender bodies. Considerable morphological differences exist among genera, three of which in the past were placed in separate families. However, they all share a very distinctive paralarva known as the doratopsis stage. Members of the family have numerous chambers in the arms, head and mantle filled with a light-weight fluid, ammonium cloride, that provides near-neutral buoyancy for the squids. Most species have extremely long, slender tentacles.

Diagnosis

Member of the chiroteuthid families ...

  • with a doratopsis paralarva.
  • with a "decorated" tail.

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Comprehensive Description

Unusual features

Doratopsis paralarvae and the adult stages of some species have a gladius that extends well posterior to the fins and supports a remarkable "tail" that bears a variety of ornamentation, mostly of uncertain function. The ornamentation may be in the form of an oval structure superficially resembling a pair of fins, or a series of small flaps and/or oval bulbs. The latter contain anastomosing canals filled with fluid that is lighter than seawater (Hunt, 1996). The overall appearance in some cases is reminescent of a siphonophore (Vecchione, et al., 1992)

Figure. Still frames from a videotape of a doratopsis (left) of Chiroteuthis calyx and the siphonophore Nanomia bijuga (right) recorded in-situ from a remotely operated vehicle (ROV) in the eastern North Pacific off California (courtesy of the Monterey Bay Aquarium Research Institute). An AVI format video clip of this animal can be seen at Cephalopods in Action.

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Nomenclature

Uncertain species:

The taxonomic position of several specimens that anchor species names is uncertain.

  1. Pfeffer (1912) described a small doratopsis as C. planctonica that he later placed in Planctoteuthis with reservations. The proper placement of this specimen is uncertain.
  2. Goodrich described a young Chiroteuthis from the Bay of Bengal that he called Doratopsis pellucida. The placement of this specimen is uncertain although it has often been assummed to be the young of C. macrosoma (= C. picteti) (e.g., Nesis 1982), presumably due to the proximity of type localities.

A list of all nominal genera and species in the Chiroteuthidae can be found here. The list includes the current status and type species of all genera, and the current status, type repository and type locality of all species and all pertinent references.

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Characteristics

  1. Arms

    Figure . Dorsal (left) and side (right) views of the same Planctoteuthis sp., Indonesian waters, about 2000 m depth. From ROV video taken during the NOAA Ocean Exploration INDEX cruise.

    1. Arms with suckers in two series.

  2. Tentacles
    1. Club very elongate and divided into two or three portions by symmetrical protective membranes except in Planctoteuthis.
    2. Club suckers in four series or absent (Grimalditeuthis) in subadults.

  3. Head
    1. Head with an elongate neck and usually a brachial pillar in subadults.

  4. Funnel
    1. Funnel locking-apparatus often oval and often with tragus and antitragus.

  5. Tail
    1. Tail, supported by gladius posterior to fins, with various "decorations" (see adjacent photographs).

  6. Photophores
    1. Present in some taxa.

  7. Paralarva
    1. Doratopsis type (see Life History).

Comments

The presence of a doratopsis paralarva and the "decorated" tail are the only characters that are unique to the family. Additional features of the family include an indistinct eyelid sinus, absence of occipital folds, olfactory organs on long stalks (=slender papillae).

Figure. Medial view of the olfactory organ of Chiroteuthis sp. from Hawaiian waters. Photograph by R. Young.

The following table compares subadults of the five chiroteuthid genera. Subadult characters for genus B, a paralarva, are assumed.

Character Planctoteuthis Chiroteuthis Asperoteuthis Grimalditeuthis Genus B Genus C
Funnel valve Absent Present Present Present ???? ????
Tentacle pads Absent Present Present Absent ???? Absent?
Arm IV photophores Absent Present Absent Absent ???? Absent
Arms IV Variable Enlarged Not enlarged Not enlarged ???? ????
Visceral photophores Absent Variable Absent Absent ???? Absent
Funnel locking-app. Antitragus Tragus & antitragus Variable Fused Antitragus ????
Arm IV suckers Absent distally Present Present Present ???? ????
Club suckers Present Present Absent proximally Absent Present Present
Club sucker series 4 4 4 0 6 4

Comments

The position of the olfactory papilla is useful in separating genera in the doratopsis stage: The organ lies near the funnel in Grimalditeuthis, just behind the eye in Chiroteuthis and Planctoteuthis and half-way between the funnel and eye in Asperoteuthis.

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Life History and Behavior

Life Cycle

Life history

All species have doratopsis paralarvae (Young, 1991).

The paralarvae live in the upper few hundred meters of the open ocean. They generally reach a very large size (up to 90 mm ML) and undergo a marked but, perhaps, gradual transition to the subadult stage. Among the changes that take place are the resorption of the paralarval tentacle clubs and formation of new clubs along the tentacular stalks, great elongation of the tentacles in most species, development of photophores in some species, loss of the tail in most species and usually a marked change in body proportions. The duration of the doratopsis stage is unknown.

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Evolution and Systematics

Evolution

Discussion of Phylogenetic Relationships

View Chiroteuthidae Tree

The relationships among the genera have not been examined with cladistic methodology. Three genera, however, can be arranged in an ordered series based on the progressive loss of suckers on the tentacular clubs. In Chiroteuthis spp. the oral surface of the club contains suckers in four series throughout its length. In Asperoteuthis spp. the proximal half of the club is bare and the distal half has suckers in four series. In Grimalditeuthis the entire oral surface of the club lacks suckers.

Figure. Oral views of the clubs of Chiroteuthis joubini (left), Asperoteuthis acanthoderma (middle) and Grimalditeuthis bonplandi (right). Drawing from Young, et al. (1999).

Roper and Young (1967) suggested that Planktoteuthis is essentially a mature doratopsis stage, based on features such as the presence in the subadult of the doratopsid tentacular club and the absence of photophores. They suggest, therefore, that the genus arose via neoteny (strong heterochrony). This interpretation gains support from the appearance, then disappearance, of suckers on the tentacular stalks of the paralarva which typically form the secondary club (see Young, 1991). The closest relative to Planktoteuthis among the other genera is unknown.

Figure. Oral view of the doratopsid club of Planctoteuthis lippula. Drawing from Young (1991).

The distinctive doratopsid club poses a problem: Is this paralarval club similar to the true adult club (i.e., the ancestral adult club) that is absent in the chiroteuthid families? Suckers at the base of the subadult club of Planctoteuthis have a distinctly different structure (i.e., wider aperatures) from those of the remaining club. These basal suckers may represent remnants of a carpal locking-apparatus and, if so, provide an important clue about the relationships of the chiroteuthid families to other oegopsid families.

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
                                        
Specimen Records:21Public Records:10
Specimens with Sequences:15Public Species:7
Specimens with Barcodes:15Public BINs:8
Species:9         
Species With Barcodes:8         
          
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© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

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Barcode data

Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

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Locations of barcode samples

Collection Sites: world map showing specimen collection locations for Chiroteuthidae

Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

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Wikipedia

Chiroteuthidae

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.

Contents

Physical description

The Chiroteuthidae are most notable for their unique paralarval stage, known as the doratopsis 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, occpital 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

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. 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

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

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