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Coleoidea
Subclass Coleoidea, or Dibranchiata, is the grouping of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e., octopuses, squid and cuttlefish). Unlike its extant sister group, Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal cuttlebone, gladius, or shell that is used for buoyancy or support. Some species have lost their cuttlebone altogether, while in some it has been replaced by a chitinous support structure. A unique trait of the group is the ability to edit their own RNA. The major divisions of Coleoidea are based upon the number of arms or tentacles and their structure. The extinct and most primitive form, the Belemnoidea, presumably had ten equally-sized arms in five pairs numbered dorsal to ventral as I, II, III, IV and V. More modern species either modified or lost a pair of arms. The superorder Decapodiformes has arm pair IV modified into long tentacles wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belemnitida
Belemnitida (or the belemnite) 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 , though a belemnite could have had between 100 and 800 hooks in total, using them to stab and hold onto prey. Belemnites were an important food source for many Mesozoic marine creatures, both the adults and the planktonic juveniles, and likely played an important role in restructuring marine ecosystems after the Triassic–Jurassic extinction event. They may have laid between 100 and 1,000 eggs. Some species may have been adapted to speed and swam in the tu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") 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 (muscular hydrostats) 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. Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids. The class now contains two, only distantly related, extant subclasses: Coleoidea, which includes octopuses, squid, and cuttlefish; and Nautiloidea, represented by '' Nautilus'' and ''Allonautilus''. In the Coleoidea, the molluscan shell has been internalized or is absent, whereas in the Nautiloidea, the external shell remains. About 800 living species of cephalopods have been ide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boletzkyida
Boletzkyida is a primitive order of teuthid coleoid cephalopod: the boletzkyids are thought to be the earliest forms of coleoid cephalopods, and appear to form a link between nautiloid orthocerids and more advanced coleoids. Boletzkyida was named and described by Bandel, Reitner, and Sturmer in 1983 (B.R.&S) from specimens found in the Lower Devonian black slate ("Hunsrück Slate") in Germany. Taxonomy Bandel, ''et al'' (1983) divided the Boletzkyida into two, not too dissimilar families, each based on a single genus. They are the Boletzkyidae based on the genus ''Boletzkya'' and the Naefiteuthidae based on the genus ''Naefiteuthis''. The main difference between ''Boletzkya'' and ''Naefiteuthis'' is the length of the phragmocone at which time the living chamber becomes gladius-like and dominates the shell. Ontogeny Boletzkyd shells grew to as long as 16 cm. The juvenile portion is a phragmocone that closely resembles that of Silurian orthocerid ''Michelinoceras'' with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octopodiformes
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 (as is the case in octopuses) or modifying the tentacles into thin filaments (as in vampire squid). 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 (all cephalopods closer to octopods than to true squid). Another term is Octobranchia, referring to cephalopods without prominent tentacles. '' Pohlsepia'', originally described as earliest octopod is considered as dubious for this group in later study. The oldest unambiguous vampyropod is ''Syllipsimopodi'', a squid-like cephalopod from the Mississippian-age Bear Gulch Lagerstätte of Montana. ''Syllipsimopodi'' has a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sepiida
Cuttlefish or cuttles are marine molluscs of the order Sepiida. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of buoyancy. Cuttlefish have large, W-shaped pupils, eight arms, and two tentacles furnished with denticulated suckers, with which they secure their prey. They generally range in size from , with the largest species, the giant cuttlefish (''Sepia apama''), reaching in mantle length and over in mass. Cuttlefish eat small molluscs, crabs, shrimp, fish, octopus, worms, and other cuttlefish. Their predators include dolphins, sharks, fish, seals, seabirds, and other cuttlefish. The typical life expectancy of a cuttlefish is about 1–2 years. Studies are said to indicate cuttlefish to be among the most intelligent invertebrates. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautiloidea
Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and '' Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species. They flourished during the early Paleozoic era, when they constituted the main predatory animals. Early in their evolution, nautiloids developed an extraordinary diversity of shell shapes, including coiled morphologies and giant straight-shelled forms (orthocones). Only a handful of rare coiled species, the nautiluses, survive to the present day. In a broad sense, "nautiloid" refers to a major cephalopod subclass or collection of subclasses (Nautiloidea ''sensu lato''). Nautiloids are typically considered one of three main groups of cephalopods, along with the extinct ammonoids (ammonites) and living coleoids (such as squid, octopus, and kin). While ammonoids and coleoids are monophyletic clades with exclusive ancestor-descendant re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeoteuthomorpha
Palaeoteuthomorpha is a superorder of primitive coleoid cephalopods, containing the Boletzkyida, characterized by an orthoceroid-like phragmocone early in ontogeny and a teuthid True squid are molluscs 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 ... living chamber later in ontogeny. This contrasts with the later Teuthida which have a reduced living chamber (gladius) throughout. References *Klaus Bandel, J Reitner, and W Sturmer, 1983. Coleoids from the Lower Devonian Black Slate (Hunstruck-Shiefer) of the Hunsruck (West Germany) N Jb Geol Paliont Abh 165(3) 397-414 Stuttgart, Apr 1983. Coleoidea Protostome superorders {{Cephalopod-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sepiolida
Bobtail squid (order Sepiolida) are a group of cephalopods closely related to cuttlefish. Bobtail squid tend to have a rounder mantle than cuttlefish and have no cuttlebone. They have eight suckered arms and two tentacles and are generally quite small (typical male mantle length being between ). Sepiolids live in shallow coastal waters of the Pacific Ocean and some parts of the Indian Ocean and Atlantic Ocean as well as in shallow waters on the west coast of the Cape Peninsula off South Africa. Like cuttlefish, they can swim by either using the fins on their mantle or by jet propulsion. They are also known as "dumpling squid" (owing to their rounded mantle) or "stubby squid". Light organ Bobtail squid have a symbiotic relationship with bioluminescent bacteria (''Aliivibrio fischeri''), which inhabit a special light organ in the squid's mantle. The luminescent properties of the bacteria regulate gene expression in the light organ. The bacteria are fed a sugar and amino acid so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuttlefish
Cuttlefish or cuttles are marine molluscs of the order Sepiida. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of buoyancy. Cuttlefish have large, W-shaped pupils, eight arms, and two tentacles furnished with denticulated suckers, with which they secure their prey. They generally range in size from , with the largest species, the giant cuttlefish (''Sepia apama''), reaching in mantle length and over in mass. Cuttlefish eat small molluscs, crabs, shrimp, fish, octopus, worms, and other cuttlefish. Their predators include dolphins, sharks, fish, seals, seabirds, and other cuttlefish. The typical life expectancy of a cuttlefish is about 1–2 years. Studies are said to indicate cuttlefish to be among the most intelligent invertebrates. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neocoleoidea
Neocoleoidea is a large group of marine cephalopods. This cohort contains two extant groups: Decapodiformes (squid, cuttlefish, and relatives) and Octopodiformes (octopuses and the vampire squid). Species within this group exist in all major habitats in the ocean, in both the southern and northern polar regions, and from intertidal zones to great depths. Whilst conventionally held to be monophyletic, the only morphological character for the group is the presence of suckers: although the presence of these features in the belemnites suggests that they do not support the Neocoleoidea, and hence that the group may be paraphyletic. Taxonomy *Superorder Decapodiformes **Order Spirulida: ram's horn squid **Order Sepiida: cuttlefish **Order Sepiolida: bobtail squid **Order Teuthida: squid *Superorder Octopodiformes **Family † Trachyteuthididae (''incertae sedis'') **Order Vampyromorphida: vampire squid **Order Octopoda: octopus *Superorder †Palaeoteuthomorpha **Order †Boletzkyi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hematitida
Hematitida is a group of coleoid cephalopods known from the early Carboniferous Period. They are the oldest definite coleoids, although there are controversial claims for even older coleoids from the Devonian. Fossil hematitidans have so far been found only in Arkansas and Utah of the United States. The only family described so far is Hematitidae. Characteristics Some features shared by hematitidans include * a short rostrum, made of aragonite and organic material, and bearing ridges * a short living chamber, only 1.5 to 2 times the length of the last chamber of the phragmocone * a spherical protoconch * a narrow, straight phragmocone * a multi-layered conotheca - the outer wall of the phragmocone * a narrow, ventral siphuncle The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, a ... C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belemnoidea
Belemnoids are an extinct group of marine cephalopod, very similar in many ways to the modern squid and closely related to the modern cuttlefish. Like them, the belemnoids possessed an ink sac, but, unlike the squid, they possessed ten Cephalopod arm, arms of roughly equal length, and no tentacles. The name "belemnoid" comes from the Greek word βέλεμνον, ''belemnon'' meaning "a dart or arrow" and the Greek word είδος, ''eidos'' meaning "form". Belemnoids include belemnites (which belong to Order (biology), order Belemnitida proper), aulacocerids (order Aulacocerida), phragmoteuthids (order Phragmoteuthida), and diplobelids (order Diplobelida). Occurrence Belemnoids were numerous during the Jurassic and Cretaceous periods, and their fossils are abundant in Mesozoic marine rocks, often accompanying their cousins the ammonites. The belemnoids become extinct at the end of the Cretaceous period along with the ammonites. The belemnoids' origin lies within the Bactritida, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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