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Search Results: 1 - 10 of 17 matches for " Cephalopoda "
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Pulido-López1,Paulo César; López-Pinto2,Yesid Antonio;
Boletín de Investigaciones Marinas y Costeras - INVEMAR , 2002,
Abstract: the occurrence of the diamond squid thysanoteuthis rhombus in the colombian caribbean is recorded for the first time based on one stranded specimen (60 cm mantle lenght) at morro de gaira, near santa marta.
Olivares Paz,Alberto; Bustos-Obregón,Eduardo; Castillo Alvarez,Vivian; Zú?iga Romero,Oscar;
International Journal of Morphology , 2003, DOI: 10.4067/S0717-95022003000400010
Abstract: male octopus mimus attains precocious maturity. in general, they are mature when their weight is 200 g or more and remain so until death. since testicular physiology in adult males is not known, spermatogenesis was analyzed by histological observation of seminiferous tubules and endocrine function by quantification of testicular concentration of progesterone and testosterone together with growth and functionality of the androgen target organs. three classes of adult males were identified : young mature, maximal maturity and regression. regressed animals produce less of both hormones tested and show spermatogenic involution. these two traits denote ageing in o. mimus. on the contrary maximal maturity shows high spermatogenic and steroidogenic function and of the glands in the reproductive male tract. these characteristics should be considered for adequate commercial exploitation of this species
Gracia C,Adriana; Ardila E,Néstor; Díaz,Juan M;
Boletín de Investigaciones Marinas y Costeras - INVEMAR , 2002,
Abstract: seven cephalopod species were identified from material collected during four exploratory cruises carried out in 1998 and 1999 along the upper shelf slope of the colombian caribbean at depths between 200 and 500 m. semirossia tenera, s. equalis, heteroteuthis dispar, opisthoteuthis agassizii, benthoctopus oregonae and octopus burryi are first recorded for the area. s. tenera was the most common species, representing 75% of the total abundance.
O enigma da "rea??o espermatofórica": breve síntese do conhecimento sobre a estrutura e o funcionamento dos espermatóforos dos cefalópodes (Mollusca: Cephalopoda)
Marian, José Eduardo Amoroso Rodriguez;
Papéis Avulsos de Zoologia (S?o Paulo) , 2011, DOI: 10.1590/S0031-10492011001300001
Abstract: coleoid cephalopods (squids, cuttlefishes, and octopods) produce elaborate spermatophores, which are transferred to the female during mating with the aid of a modified appendage called hectocotylus. during transfer, the spermatophores undergo the so-called spermatophoric reaction, i.e., a complex process of evagination of the ejaculatory apparatus that, ultimately, leads to the extrusion of the cement body and sperm mass. the present review summarizes the bulk of our knowledge on the morphology and functioning of this exclusive coleoid character, identifying gaps and defining strategies to stimulate advancements in this area. few detailed morphological studies regarding this structure have yet been conducted, and much of the knowledge on the coleoid spermatophore was generated by classical studies of the 19th and early 20th centuries. furthermore, investigations on the functioning of this structure are even rarer, the basic knowledge of the spermatophoric reaction being restricted to 19 species. there seems to be a consensus in the literature that two types of attachment of spermatophores occur in decapodiforms (i.e., squids and sepioids): superficial attachment, and deep (or intradermal) implantation. in superficial attachment, the base of the spermatangia ends up attached on the surface of the female's body, by means of the adhesive contents and, in some cases, attachment structures of the cement body; this type is found in several groups of decapodiforms (e.g., loliginidae, ommastrephidae, sepiidae). in deep implantation, the spermatangia penetrate autonomously the integument, embedding themselves completely into the female tissue; this strategy is common to some oceanic and deep-sea species (e.g., architeuthidae, cranchiidae, octopoteuthidae, sepiolidae). the mechanism responsible for deep implantation remains unknown. in octopodiforms (octopods), the spermatophore is inserted inside the lumen of the female gonoduct, reaching the oviducal gland, where the sperma
A multi-gene phylogeny of Cephalopoda supports convergent morphological evolution in association with multiple habitat shifts in the marine environment
Lindgren Annie R,Pankey Molly S,Hochberg Frederick G,Oakley Todd H
BMC Evolutionary Biology , 2012, DOI: 10.1186/1471-2148-12-129
Abstract: Background The marine environment is comprised of numerous divergent organisms living under similar selective pressures, often resulting in the evolution of convergent structures such as the fusiform body shape of pelagic squids, fishes, and some marine mammals. However, little is known about the frequency of, and circumstances leading to, convergent evolution in the open ocean. Here, we present a comparative study of the molluscan class Cephalopoda, a marine group known to occupy habitats from the intertidal to the deep sea. Several lineages bear features that may coincide with a benthic or pelagic existence, making this a valuable group for testing hypotheses of correlated evolution. To test for convergence and correlation, we generate the most taxonomically comprehensive multi-gene phylogeny of cephalopods to date. We then create a character matrix of habitat type and morphological characters, which we use to infer ancestral character states and test for correlation between habitat and morphology. Results Our study utilizes a taxonomically well-sampled phylogeny to show convergent evolution in all six morphological characters we analyzed. Three of these characters also correlate with habitat. The presence of an autogenic photophore (those relying upon autonomous enzymatic light reactions) is correlated with a pelagic habitat, while the cornea and accessory nidamental gland correlate with a benthic lifestyle. Here, we present the first statistical tests for correlation between convergent traits and habitat in cephalopods to better understand the evolutionary history of characters that are adaptive in benthic or pelagic environments, respectively. Discussion Our study supports the hypothesis that habitat has influenced convergent evolution in the marine environment: benthic organisms tend to exhibit similar characteristics that confer protection from invasion by other benthic taxa, while pelagic organisms possess features that facilitate crypsis and communication in an environment lacking physical refuges. Features that have originated multiple times in distantly related lineages are likely adaptive for the organisms inhabiting a particular environment: studying the frequency and evolutionary history of such convergent characters can increase understanding of the underlying forces driving ecological and evolutionary transitions in the marine environment.
Eoteuthoidae - a new family of Late Cretaceous dibranchiate cephalopods (Coleoidea, Decapoda, Teuthina?)
Ko??ák M
Bulletin of Geosciences , 2003, DOI: 10.3140/bull.geosci.2003.02.157
Abstract: On the basis of a uniquely preserved gladius of the Turonian coleoid cephalopod, the new genus Eoteuthoides Kostak, 2002, and the new family Eoteuthoidae fam. nov. are established. Designation of a new higher taxomomic unit is based on marked morphological differences from all known fossil taxa. Eoteuthoides shows strong affinities to some living families.
Colour pattern polymorphism in Silurian nautiloid Phragmoceras Broderip, 1839
Turek V,Manda ?
Bulletin of Geosciences , 2011, DOI: 10.3140/bull.geosci.1240
Abstract: Flamboyant colour pattern polymorphism documented in Silurian nautiloid Phragmoceras has not been observed in any other nautiloid genus. Two specimens of P. imbricatum Barrande, one from the early Ludlow of Bohemia and the second from the late Wenlock of England display quite different shell coloration: narrow, densely spaced longitudinal bands subparallel to the shell axis, combined with narrower transversal bands versus transverse bands running laterally obliquely to growth lamellae. Two additional types of colouration have been observed in several specimens of Phragmoceras from the early Wenlock and late Ludlow of Gotland. The colour pattern in P. eurystoma flexibile Hedstr m consists of zigzags bands around the whole circumference of the shell. In contrast, distinct colour bands following growth lines along the whole circumference of the shell, like that in the Cretaceous nautilid Eutrephoceras, are characteristic in P. dubium Hedstr m. If pigmentation pattern served as a form of crypsis, then the quite different types of coloration in Phragmoceras indicate different solutions of this problem. Colour pattern has been regarded as a useful tool also for taxonomic purposes in nautiloid cephalopods. Nevertheless, the colour polymorphism in Phragmoceras suggests the limited significance of this feature for the taxonomy of nautiloids. Some other remarkable cases of colour variations in Silurian nautiloids are discussed. Changes in colour pattern most probably correspond with depth inhabited; nautiloids that occupied shallow water environments display rather light coloured shells in comparison with forms inhabiting a deeper water setting.
Some observations on bactritid cephalopods
Holland C H
Bulletin of Geosciences , 2003, DOI: 10.3140/bull.geosci.2003.04.369
Abstract: The classification of the Class Cephalopoda and the systematic position of the Order Bactritida within it are reviewed. The Middle Ordovician genus Eobactrites was probably the first representative of the Bactritida. There is a definite record in the Silurian of the Czech Republic and a possible occurrence in Northern England. The mode of life of these cephalopods is briefly considered.
On the occurrence of Neorossia caroli (Jouben, 1902) in the central Adriatic Sea (Croatian waters)
Acta Adriatica , 2007,
Abstract: Two specimens of Neorossia caroli have been recorded for the first time in the central Adriatic Sea. They were caught in summer 2004 with a bottom-trawl net during a single tow at depths between 449 and 594 m in Croatian waters. Up to now N. caroli has never been found in the central Adriatic area. This finding represents a northernmost extension in the known range of the species N. caroli in the Adriatic Sea. Recorded specimens were both adult and mature males with mantle lengths of 42 and 37 mm. They counted 21 and 16 spermatophores, respectively. The measurements from both individuals are reported, including beak standard dimensions.
Molluscan fauna of Gueishan Island, Taiwan
Chih-Wei Huang,Ta-Wei Hsiung,Si-Min Lin,Wen-Lung Wu
ZooKeys , 2013, DOI: 10.3897/zookeys.261.4197
Abstract: This dataset records the occurrence and inventory of molluscan fauna on Gueishan Island, the only active volcanic island in Taiwan, based on the literature survey and field investigation conducted between 2011 and 2012. The literature review involved seven studies published from 1934 to 2003, which collectively reported 112 species from 61 genera and 37 families of Mollusca on Gueishan Island. Through our field investigation, we identified 34 species from 28 genera and 23 families. Fourteen of these species were new records on Gueishan Island: Liolophura japonica, Lottia luchuana, Nerita costata, Nerita rumphii, Diplommatina suganikeiensis, Littoraria undulata, Solenomphala taiwanensis, Assiminea sp., Siphonaria laciniosa, Laevapex nipponica, Carychium hachijoensis, Succinea erythrophana, Zaptyx crassilamellata, and Allopeas pyrgula. In Total, there are 126 species from 71 genera and 45 families of Mollusca on Gueishan Island. These data have been published through GBIF [http://taibif.org.tw/ipt/resource.do?r=gueishan_island] and integrated into the Taiwan Malacofauna Database (http://shell.sinica.edu.tw/).
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