Chiroteuthidae
Encyclopedia
Chiroteuthids are deep-sea squid
of the family Chiroteuthidae. They are 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 twelve species
and four subspecies
in four genera
, two of which are monotypic
. They are sometimes known collectively as whip-lash squid: However, this common name is also applied to the Mastigoteuthidae, which is itself 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.
The Chiroteuthidae are most notable for their unique paralarva
l stage, known as the doratopsis stage (see Life history). Although morphology
varies greatly within the family, the Chiroteuthidae are distinguished by their extremely elongate bodies and (in most species) tentacle
s; the latter may be up to four times the mantle
length in Asperoteuthis acanthoderma
. The head is atop an elongate neck and the brachial pillar is well-developed, the eye
s 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, ca. 50 percent 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 elongate and—with the exception of Planctoteuthis species—are subdivided by symmetrical, protective membranes into 2–3 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 photophore
s (light-producing organs) variably present on the inner surface of the ventral arms, on the ventral surface of the eyes (1–3 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 ca. 78 centimetres. Body coloration is typically beige to sepia, but Asperoteuthis acanthoderma is noted for its deep violet colour.
and slowly undergo a marked transformation to subadults. During the doratopsis stage, the paralarval chiroteuthids possess 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 elongate neck and brachial pillar are chambered, and there is vesicular tissue 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 elongate (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.
The species listed above with an asterisk (* ) is questionable and needs further study to determine if it is a valid species or a synonym.
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
of the family Chiroteuthidae. They are 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
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, North Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, and Indo-Pacific
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
. The family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
is represented by approximately twelve species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
and four subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
in four genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
, two of which are monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
. They are sometimes known collectively as whip-lash squid: However, this common name is also applied to the Mastigoteuthidae, which is itself 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.
Physical description
Paralarva
Paralarvae is the term used to describe the young planktonic stages of cephalopods, between hatchling and subadult. It is used to differentiate it from the term 'larva' used in animals which undergo true metamorphosis. They have been observed only on members of the orders Octopoda and Teuthida.The...
l stage, known as the doratopsis stage (see Life history). Although morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
varies greatly within the family, the Chiroteuthidae are distinguished by their extremely elongate bodies and (in most species) tentacle
Tentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s; the latter may be up to four times the mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
length in Asperoteuthis acanthoderma
Asperoteuthis acanthoderma
Asperoteuthis acanthoderma is a species of squid belonging to the family Chiroteuthidae. It is characterised by the tiny, pointed tubercules present on its skin and a Y-shaped groove in the funnel locking-apparatus....
. The head is atop an elongate neck and the brachial pillar is well-developed, the eye
Cephalopod eye
Cephalopods, as active marine predators, possess sensory organs specialized for use in aquatic conditions. They have a camera-type eye, which consists of a lens projecting an image onto a retina. Unlike the vertebrate camera eye, the cephalopods' form as invaginations of the body surface , and...
s large; in some Planctoteuthis
Planctoteuthis
Planctoteuthis is a genus of chiroteuthid squid comprising five species, occurring worldwide in lower mesopelagic to bathypelagic depths in tropical to temperate waters. It has been suggested that members of Planctoteuthis are neotenic, retaining characteristics of the doratopsis developmental stage...
and all Chiroteuthis
Chiroteuthis
Chiroteuthis is a genus of chiroteuthid squid, comprising two subgenera. The hectocotylus is absent from all members of the genus; instead, a penis extending from the mantle opening is utilised. The genus is characterised by enlarged, lidded photophores present at the end of the tentacular club...
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, ca. 50 percent mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
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 elongate and—with the exception of Planctoteuthis species—are subdivided by symmetrical, protective membranes into 2–3 parts.
The funnel
Funnel
A funnel is a pipe with a wide, often conical mouth and a narrow stem. It is used to channel liquid or fine-grained substances into containers with a small opening. Without a funnel, spillage would occur....
-locking apparatus is oval; its cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
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
Bioluminescence
Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...
, with photophore
Photophore
A photophore is a light-emitting organ which appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors...
s (light-producing organs) variably present on the inner surface of the ventral arms, on the ventral surface of the eyes (1–3 patches or bands), on the ink sac
Ink sac
With the exception of nocturnal and very deep water cephalopods, all coeloids which dwell in light conditions have an ink sac, which can be used to expel a cloud of dark ink to confuse predators. This sac is a muscular bag which originated as an extension of the hind gut...
, and near the club terminus. A number of chambers containing ammonium chloride
Ammonium chloride
Ammonium chloride NH4Cl is an inorganic compound with the formula NH4Cl. It is a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of natural, mineralogical form of ammonium chloride...
are contained within the arms, head, and mantle. With a lower density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
than the surrounding seawater
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
, the ammonium chloride helps chiroteuthids to conserve energy reserved for swimming by maintaining the body's neutral buoyancy
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
. The eyelid sinus is indistinct, occpital folds are absent, and long stalks support the olfactory
Olfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...
papillae. The largest species reach a mantle length of ca. 78 centimetres. Body coloration is typically beige to sepia, but Asperoteuthis acanthoderma is noted for its deep violet colour.
Life history
Little is known of chiroteuthid reproduction. The distinctive doratopsis paralarvae are thought to remain within the first few hundred metres of the water column, where they likely feed on zooplanktonZooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
and slowly undergo a marked transformation to subadults. During the doratopsis stage, the paralarval chiroteuthids possess 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 elongate neck and brachial pillar are chambered, and there is vesicular tissue 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 elongate (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
Neoteny
Neoteny , also called juvenilization , is one of the two ways by which paedomorphism can arise. Paedomorphism is the retention by adults of traits previously seen only in juveniles, and is a subject studied in the field of developmental biology. In neoteny, the physiological development of an...
. The time frame of the doratopsis stage, including the onset or loss of specific features, is unknown.
Species
- Genus AsperoteuthisAsperoteuthisAsperoteuthis is a genus of chiroteuthid squid comprising four species.-References:*Lu, C.C. 1977. A new species of squid, Chiroteuthis acanthoderma, from the Southwestern Pacific . Steenstrupia Zoological Museum University of Copenhagen 4: 179–188.*Young, R.E., M. Vecchione & C.F.E. Roper 2007...
- Asperoteuthis acanthodermaAsperoteuthis acanthodermaAsperoteuthis acanthoderma is a species of squid belonging to the family Chiroteuthidae. It is characterised by the tiny, pointed tubercules present on its skin and a Y-shaped groove in the funnel locking-apparatus....
- Asperoteuthis luiAsperoteuthis luiAsperoteuthis lui is a chiroteuthid squid of the genus Asperoteuthis. This species was discovered from the stomach contents of a ling, a species of fish. The damaged specimen did not include a funnel or a mantle, but had multiple arms, one tentacle, and eyes. It was initially identified as a...
- Asperoteuthis mangoldaeAsperoteuthis mangoldaeAsperoteuthis 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...
- Asperoteuthis nesisiAsperoteuthis nesisiAsperoteuthis nesisi is a chiroteuthid squid of the genus Asperoteuthis. It is native to the waters off South Georgia and, more generally, the Southwest Atlantic. Asperoteuthis nesisi has a thin mantle and arms, and peculiar integumental tubercles on its head and mantle. The largest arm suckers...
- Asperoteuthis acanthoderma
- Genus ChiroteuthisChiroteuthisChiroteuthis is a genus of chiroteuthid squid, comprising two subgenera. The hectocotylus is absent from all members of the genus; instead, a penis extending from the mantle opening is utilised. The genus is characterised by enlarged, lidded photophores present at the end of the tentacular club...
- Chiroteuthis sp. B2
- Subgenus Chiroteuthis
- Chiroteuthis calyx
- Chiroteuthis joubini
- Chiroteuthis spoeli
- Chiroteuthis veranyiChiroteuthis veranyiChiroteuthis veranyi, 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....
, Long-armed Squid- Chiroteuthis veranyi lacertosa
- Chiroteuthis veranyi veranyi
- Subgenus Chirothauma
- Chiroteuthis atlanticus *
- Chiroteuthis imperatorChiroteuthis imperatorChiroteuthis imperator is a species of chiroteuthid squid. It lives of the coast of Sumatra. It grows to a mantle length of 30 cm....
- Chiroteuthis mega
- Chiroteuthis picteti
- Chiroteuthis picteti picteti
- Chiroteuthis picteti somaliensis
- Genus Grimalditeuthis
- Grimalditeuthis bonplandiGrimalditeuthis bonplandiGrimalditeuthis bonplandi is a squid named after the Grimaldi family, reigning house of Monaco. His Serene Highness 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.-External links:*...
- Grimalditeuthis bonplandi
- Genus PlanctoteuthisPlanctoteuthisPlanctoteuthis is a genus of chiroteuthid squid comprising five species, occurring worldwide in lower mesopelagic to bathypelagic depths in tropical to temperate waters. It has been suggested that members of Planctoteuthis are neotenic, retaining characteristics of the doratopsis developmental stage...
- Planctoteuthis danaePlanctoteuthis danaePlanctoteuthis danae is a species of chiroteuthid squid. It is distinguished from further members of Planctoteuthis by a fin length greater than half of the mantle. During the paralarval stage, the species occurs in depths of 200–300 m, progressing to 200–800 m at 10-15mm ML; larger specimens have...
- Planctoteuthis exopthalmica
- Planctoteuthis levimana
- Planctoteuthis lippula
- Planctoteuthis oligobessa
- Planctoteuthis danae
- Genus "New Genus B"
- Genus "New Genus C"
The species listed above with an asterisk (