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Spirulida
Spirulida is an order of cephalopods comprising one extant species ('' Spirula spirula'') and several extinct taxa. Fossil record * Oldest representative: Carboniferous, though contested: see '' Shimanskya'' * Oldest uncontested representative: Late Jurassic Classification *Order Spirulida **?Family † Shimanskyidae **Suborder †Groenlandibelina Khromov, 1990 ***Family † Groenlandibelidae ***Family †Adygeyidae **Suborder †Belopterina Engeser, 1998 ***Family † Belemnoseidae ***Family † Belopteridae **Suborder Spirulina Pompeckj, 1912 ***Family † Spirulirostridae ***Family † Spirulirostrinidae ***Family Spirulidae ''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 k ... References Tree of Life: Spirulida [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spirula
''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. Live specimens of this cephalopod are very rarely seen because it is a deep-ocean dweller. The small internal shell of the species is, however, quite a familiar object to many beachcombers. The shell of ''Spirula'' is extremely light in weight, very buoyant, and surprisingly durable; it very commonly floats ashore onto tropical beaches (and sometimes even temperate beaches) all over the world. This seashell is known to shell collectors as the ram's horn shell or simply as ''Spirula''. Description ''S. spirula'' has a squid-like body between 35 mm and 45 mm long. It i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spirula Spirula
''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. Live specimens of this cephalopod are very rarely seen because it is a deep-ocean dweller. The small internal shell of the species is, however, quite a familiar object to many beachcombers. The shell of ''Spirula'' is extremely light in weight, very buoyant, and surprisingly durable; it very commonly floats ashore onto tropical beaches (and sometimes even temperate beaches) all over the world. This seashell is known to shell collectors as the ram's horn shell or simply as ''Spirula''. Description ''S. spirula'' has a squid-like body between 35 mm and 45 mm long. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalopod Orders
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 identified. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
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] |
Shimanskya
''Shimanskya'' is a late Carboniferous fossil tentatively interpreted as an early spirulid. This identification was based on: Doguzhaeva ''et al.'' also identify these features in living Spirula, and the fossil 'Spirulida' Naefia, '' Groenlandibelus'' and '' Adygeya''—though see these respective articles for discussion as to whether or not these extinct genera are themselves Spiruliids. Some authors are happy to accept this designation. But others have argued that none of the characters observed in ''Shimanskya'' is clearly diagnostic of the Spirulids. For example, a nacreous layer may have been lost more than once in cephalopod evolution. Others view the microstructural evidence as ambiguous. Interpreting ''Shimanskya'' as a spirulid creates a large gap in the fossil record of the lineage. Moreover, some molecular clock results predict that spirulids evolved much later than the Carboniferous, leading some to suggest that ''Shimanskya'' ought to be assigned to the col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shimanskyidae
''Shimanskya'' is a late Carboniferous fossil tentatively interpreted as an early spirulid. This identification was based on: Doguzhaeva ''et al.'' also identify these features in living Spirula, and the fossil 'Spirulida' Naefia, '' Groenlandibelus'' and '' Adygeya''—though see these respective articles for discussion as to whether or not these extinct genera are themselves Spiruliids. Some authors are happy to accept this designation. But others have argued that none of the characters observed in ''Shimanskya'' is clearly diagnostic of the Spirulids. For example, a nacreous layer may have been lost more than once in cephalopod evolution. Others view the microstructural evidence as ambiguous. Interpreting ''Shimanskya'' as a spirulid creates a large gap in the fossil record of the lineage. Moreover, some molecular clock results predict that spirulids evolved much later than the Carboniferous, leading some to suggest that ''Shimanskya'' ought to be assigned to the col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adygeyidae
''Adygeya'' is a genus of cephalopods assigned to the Spirulida.Doguzhaeva, L. A., Mapes, R. H., & Mutvei, H. (1999). A Late Carboniferous spirulid coleoid from the southern mid-continent (USA): shell wall ultrastructure and evolutionary implications. In F. Olóriz & F. J. Rodríguez-Tovar (Eds.), Advancing Research on Living and Fossil Cephalopods (pp. 47–57). New York: Kluwer Academic Publishers. References Coleoidea {{paleo-cephalopod-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Record
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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