A squid is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida. 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.
The vampire squid is a small cephalopod found throughout temperate and tropical oceans in extreme deep sea conditions. The vampire squid uses its bioluminescent organs and its unique oxygen metabolism to thrive in the parts of the ocean with the lowest concentrations of oxygen. It has two long retractile filaments, located between the first two pairs of arms on its dorsal side, which distinguish it from both octopuses and squids, and places it in its own order, Vampyromorphida, although its closest relatives are octopods. As a phylogenetic relict, it is the only known surviving member of its order.
Vampyromorphida is an order of cephalopods comprising one known extant species and many extinct taxa. Physically, they somewhat resemble octopuses, but are often called vampire squids. Unlike octopuses, their eight arms are united by a web of skin, and two smaller cilia are also present. Properly speaking, the vampire squid does not possess cilia, but cirri.
Coleoidea or Dibranchiata is one of the two subclasses of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less". Unlike its extant sister group Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal shell called cuttlebone or gladius that is used for buoyancy or as muscle anchorage. Some species, notably incirrate octopuses, have lost their internal shell altogether, while in some it has been replaced by a chitinous support structure.
Cephalopod intelligence is a measure of the cognitive ability of the cephalopod class of molluscs.
The evolution of the molluscs is the way in which the Mollusca, one of the largest groups of invertebrate animals, evolved. This phylum includes gastropods, bivalves, scaphopods, cephalopods, and several other groups. The fossil record of mollusks is relatively complete, and they are well represented in most fossil-bearing marine strata. Very early organisms which have dubiously been compared to molluscs include Kimberella and Odontogriphus.
Octopodiformes is a superorder of the subclass Coleoidea, comprising the octopuses and the vampire squid. All living members of Octopodiformes have eight arms, either lacking the two tentacles of squid or modifying the tentacles into thin filaments. Octopodiformes is often considered the crown group of octopuses and vampire squids, including all descendants of their common ancestor. Some authors use the term Vampyropoda for the same general category, though others use "Vampyropoda" to refer to the total group. Another term is Octobranchia, referring to cephalopods without prominent tentacles.
Cephalopods, which include squids and octopuses, vary enormously in size. The smallest are only about 1 centimetre (0.39 in) long and weigh less than 1 gram (0.035 oz) at maturity, while the giant squid can exceed 10 metres (33 ft) in length and the colossal squid weighs close to half a tonne (1,100 lb), making them the largest living invertebrates. Living species range in mass more than three-billion-fold, or across nine orders of magnitude, from the lightest hatchlings to the heaviest adults. Certain cephalopod species are also noted for having individual body parts of exceptional size.
Vampyronassa rhodanica is an extinct vampyromorph cephalopod known from around 20 fossils from the Lower Callovian of La Voulte-sur-Rhône, Ardèche, France.
The cephalopods have a long geological history, with the first nautiloids found in late Cambrian strata.
Belemnitida is an extinct order of squid-like cephalopods that existed from the Late Triassic to Late Cretaceous. Unlike squid, belemnites had an internal skeleton that made up the cone. The parts are, from the arms-most to the tip: the tongue-shaped pro-ostracum, the conical phragmocone, and the pointy guard. The calcitic guard is the most common belemnite remain. Belemnites, in life, are thought to have had 10 hooked arms and a pair of fins on the guard. The chitinous hooks were usually no bigger than 5 mm (0.20 in), though a belemnite could have had between 100 and 800 hooks in total, using them to stab and hold onto prey.
Leptotheuthis is a monospecific genus of cephalopod known primarily from gladii, with soft parts often preserved in the German Solnholfen limestone. The name is sometimes misspelled as Leptoteuthis, after an unjustified emendation published in 1845.
All extant cephalopods have a two-part beak, or rostrum, situated in the buccal mass and surrounded by the muscular head appendages. The dorsal (upper) mandible fits into the ventral (lower) mandible and together they function in a scissor-like fashion. The beak may also be referred to as the mandibles or jaws. These beaks are different from bird beaks because they crush bone while most bird beaks do not.
This list of fossil molluscs described in 2021 is a list of new taxa of fossil molluscs that were described during the year 2021, as well as other significant discoveries and events related to molluscan paleontology that occurred in 2021.
This list of fossil molluscs described in 2022 is a list of new taxa of fossil molluscs that were described during the year 2022, as well as other significant discoveries and events related to molluscan paleontology that occurred in 2022.
Syllipsimopodi is an extinct member of the cephalopod subclass Coleoidea originally interpreted to belong to the clade Vampyropoda, which includes octopuses (Octopoda) and vampire squids (Vampyromorphida). The type and only known species is Syllipsimopodi bideni, named in honor of US President Joe Biden, and to raise awareness of his climate change policies. The holotype fossil was found in the Bear Gulch Limestone deposit in the US state of Montana in 1988, and donated that year to the Royal Ontario Museum by B. Hawes, designated ROMIP 64897. The species lived during the (Carboniferous) Mississippian subperiod, 330.3 to 323.4 million years ago, pushing back the group of cephalopods by 81.9 million years.
Provampyroteuthis is an extinct genus of vampire squids from the Late Cretaceous of Japan. It contains one species, P. giganteus. It is known from several beaks found as the stomach contents of an elasmosaurid. The validity of the genus has more recently been questioned.
Necroteuthis is an extinct genus of vampire squids from the Oligocene of Hungary. It contains one species, N. hungarica. It was initially identified as a squid, but was recently reinterpreted as a vampyroteuthid.
