A squid is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting these criteria. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius or pen, made of chitin.
A cephalopod is any member of the molluscan class Cephalopoda such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology.
Spirula spirula is a species of deep-water squid-like cephalopod mollusk. It is the only extant member of the genus Spirula, the family Spirulidae, and the order Spirulida. Because of the shape of its internal shell, it is commonly known as the ram's horn squid or the little post horn squid. Because the live animal has a light-emitting organ, it is also sometimes known as the tail-light squid.
The Mastigoteuthidae, also known as whip-lash squid, are a family of small deep-sea squid. Approximately 20 known species in six genera are represented, with members found in both the mesopelagic and bathypelagic zone of most oceans. Originally described by Verill in 1881, it was later lowered by Chun (1920) to a subfamily (Mastigoteuthinae) of the Chiroteuthidae. However, Roper et al. (1969) raised it back to the family level, and this has not been changed since. The taxonomy of this family is extremely unstable, and there have been at times one genus, two genera and four subgenera(Salcedo-Vargas & Okutani, 1994), two genera and several 'groups', five genera and one species with an uncertain placement, or six genera.
The hooked squid, family Onychoteuthidae, currently comprise about 20–25 species, in six or seven genera. They range in mature mantle length from 7 cm to a suggested length of 2 m for the largest member, Onykia robusta. The family is characterised by the presence of hooks only on the tentacular clubs, a simple, straight, funnel–mantle locking apparatus, and a 'step' inside the jaw angle of the lower beak. With the exception of the Arctic Ocean, the family is found worldwide.
Lepidoteuthis grimaldii, also known as the Grimaldi scaled squid, is a large squid growing to 1 m in mantle length. It is 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 Grimaldi scaled squid was first collected from the stomach contents of a sperm whale. It is a widely distributed species in tropical and subtropical areas of the North and South Atlantic, the southern Indian Ocean and the Pacific Ocean, where it has been recorded off Japan and in the west Pacific.
Myopsida is one of the four orders of squid. It consists of two families: the monotypic Australiteuthis and the diverse and commercially important Loliginidae. Some taxonomists classify this taxon as a suborder of the order Teuthida, in which case it is known as Myopsina. This reclassification is due to Myopsina and Oegopsina not being demonstrated to form a clade.
Histioteuthidae is a family of Oegopsid squid. The family was previously considered to be monotypic but the World Register of Marine Species assigns two genera to this family.
Onykia ingens, the greater hooked squid, is a species of squid in the family Onychoteuthidae. It occurs worldwide in subantarctic oceans.
Onykia robusta, also known as the robust clubhook squid and often cited by the older name Moroteuthis robusta, is a species of squid in the family Onychoteuthidae. Reaching a mantle length of 2 m (6.6 ft), it is the largest member of its family and one of the largest of all cephalopods. The tentacular clubs are slender, containing 15–18 club hooks. Arms of the species contain 50–60 suckers, and grow to 90–100% of the mantle length. It is found primarily in the boreal to Temperate Northern Pacific.
A. aldrichi is a small species of squid found in northern Australian waters. The species was described by Chung Cheng Lu in 2005 based on specimens collected in the inshore waters of Northern Australia. The largest known individual of this species is a mature female measuring 27.6 mm (1.09 in) in mantle length (ML). The holotype is a mature male of 21.3 mm (0.84 in) ML. A live specimen of A. aldrichi has yet to be recorded. A. aldrichi is a member of the class Cephalopoda and part of the subclass Coleodia. Within this class there are two orders, the Myopsida and Oegopsida, which both fall under the superorder Decapodiformes. A. aldrichi falls under the order of Myospida, and is the only member of its genus, Australiteuthis, and family, Australiteuthidae.
Magnapinna talismani is a species of bigfin squid known only from a single damaged specimen. It is characterised by small white nodules present on the ventral surface of its fins.
The thorny whiplash squid, known as Asperoteuthis acanthoderma is a large 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.
Histioteuthis bonnellii, the umbrella squid, is a species of cock-eyed squid belonging to the family Histioteuthidae.
Sepiolina nipponensis, also known as the Japanese bobtail squid, is a bobtail squid and one of two species in the genus Sepiolina. It is found in the Western Pacific in apparently widely separated populations, the most southerly of which is in the Great Australian Bight in South Australia and Western Australia, and there are populations from the Philippines northwards to Taiwan, Fujian and southern Honshū.
The funnel–mantle locking apparatus is a structure found in many cephalopods that connects the mantle and hyponome (funnel) and restricts their movement relative to each other. It consists of two interlocking components: one located on the mantle and the other on the funnel. The apparatus may permit some anterior–posterior displacement or prevent movement altogether.
Teuthowenia megalops, sometimes known as the Atlantic cranch squid, is a species of glass squid from the subarctic and temperate waters of the northern Atlantic Ocean. They are moderately sized squid with a maximum mantle length of 40 cm (16 in). Their very large eyes are the source for the specific name megalops. Like other members of the genus Teuthowenia, they are easily recognizable by the presence of three bioluminescent organs (photophores) on their eyeballs.
Cephalopod fins, sometimes known as wings, are paired flap-like locomotory appendages. They are found in ten-limbed cephalopods as well as in the eight-limbed cirrate octopuses and vampire squid. Many extinct cephalopod groups also possessed fins. Nautiluses and the more familiar incirrate octopuses lack swimming fins. An extreme development of the cephalopod fin is seen in the bigfin squid of the family Magnapinnidae.
Slosarczykovia is a monotypic genus of squid, its sole representative being Slosarczykovia circumantarctica. Slosarczykovia is placed in the family Brachioteuthidae.
Histioteuthis meleagroteuthis is a species of small to medium squids that have a dark, wine-red skin pigment. Females at maturity average at 114 mm (4.5 in) in length, while males at maturity average at 65 to 102 mm in length. This species is characterized by tubercles, photophores, and asymmetric features. This species can be found in circumglobal, mesopelagic waters.
Mature female of Onykia ingens (38.4 cm ML)
Piece of ventral mantle skin from O. ingens
Closeup of the dermal warts from the same O. robsoni specimen
Dorsal mantle of Slosarczykovia circumantarctica (12.2 cm ML)
Ocythoe tuberculata with ridges and tubercles visible on mantle
