Sample records for decapodiformes
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The functional-morphological adaptive strategy of digestive organs of decapodiform cephalopods
OMURA, Ayano; ENDO, Hideki
2015-01-01
The digestive organs in decapodiform cephalopod species morphologically vary by individual lifestyle. We examined the following six species of adult decapodiformes cephalopods representing different habitats: Todarodes pacificus, Loligo bleekeri, Loligo edulis, Watasenia scintillans (pelagic), Sepia lycidas and Euprymna morsei (benthic). L. bleekeri and L. edulis possess a bursiform cecal sac connected to the cecum. Pelagic species have a single digestive gland smaller than in benthic species. T. pacificus has an oval digestive gland larger than that of L. bleekeri and L. edulis, which possess withered-looking and smaller digestive glands. In contrast, the digestive glands in benthic species are paired. S. lycidas and E. morsei have well-developed and larger digestive glands than those of the pelagic species. Well-developed digestive duct appendages are found in benthic species. In qualification of the mass of digestive organs, pelagic species have smaller stomachs, digestive glands and digestive ducts’ appendages than benthic species. Because pelagic species need to swim, they may possess smaller stomachs and larger cecums for more rapid digestion. A smaller digestive gland may have the advantage of reducing the body weight in pelagic species for rapid swimming. In contrast, since benthic species require a longer time for digestion than pelagic species, they compact more food in their stomachs and absorb nutrients via more organs, such as the digestive grand and digestive duct appendages, in addition to cecum. PMID:26369293
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The functional-morphological adaptive strategy of digestive organs of decapodiform cephalopods.
Omura, Ayano; Endo, Hideki
2016-01-01
The digestive organs in decapodiform cephalopod species morphologically vary by individual lifestyle. We examined the following six species of adult decapodiformes cephalopods representing different habitats: Todarodes pacificus, Loligo bleekeri, Loligo edulis, Watasenia scintillans (pelagic), Sepia lycidas and Euprymna morsei (benthic). L. bleekeri and L. edulis possess a bursiform cecal sac connected to the cecum. Pelagic species have a single digestive gland smaller than in benthic species. T. pacificus has an oval digestive gland larger than that of L. bleekeri and L. edulis, which possess withered-looking and smaller digestive glands. In contrast, the digestive glands in benthic species are paired. S. lycidas and E. morsei have well-developed and larger digestive glands than those of the pelagic species. Well-developed digestive duct appendages are found in benthic species. In qualification of the mass of digestive organs, pelagic species have smaller stomachs, digestive glands and digestive ducts' appendages than benthic species. Because pelagic species need to swim, they may possess smaller stomachs and larger cecums for more rapid digestion. A smaller digestive gland may have the advantage of reducing the body weight in pelagic species for rapid swimming. In contrast, since benthic species require a longer time for digestion than pelagic species, they compact more food in their stomachs and absorb nutrients via more organs, such as the digestive grand and digestive duct appendages, in addition to cecum.
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Lindgren, Annie R; Anderson, Frank E
2018-01-01
Historically, deep-level relationships within the molluscan class Cephalopoda (squids, cuttlefishes, octopods and their relatives) have remained elusive due in part to the considerable morphological diversity of extant taxa, a limited fossil record for species that lack a calcareous shell and difficulties in sampling open ocean taxa. Many conflicts identified by morphologists in the early 1900s remain unresolved today in spite of advances in morphological, molecular and analytical methods. In this study we assess the utility of transcriptome data for resolving cephalopod phylogeny, with special focus on the orders of Decapodiformes (open-eye squids, bobtail squids, cuttlefishes and relatives). To do so, we took new and previously published transcriptome data and used a unique cephalopod core ortholog set to generate a dataset that was subjected to an array of filtering and analytical methods to assess the impacts of: taxon sampling, ortholog number, compositional and rate heterogeneity and incongruence across loci. Analyses indicated that datasets that maximized taxonomic coverage but included fewer orthologs were less stable than datasets that sacrificed taxon sampling to increase the number of orthologs. Clades recovered irrespective of dataset, filtering or analytical method included Octopodiformes (Vampyroteuthis infernalis + octopods), Decapodiformes (squids, cuttlefishes and their relatives), and orders Oegopsida (open-eyed squids) and Myopsida (e.g., loliginid squids). Ordinal-level relationships within Decapodiformes were the most susceptible to dataset perturbation, further emphasizing the challenges associated with uncovering relationships at deep nodes in the cephalopod tree of life. Copyright © 2017 Elsevier Inc. All rights reserved.
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Hendrickx, Michel E.; Urbano, Brian; Zamorano, Pablo
2015-01-01
Abstract The oegopsid squids Abraliopsis and Pterygioteuthis are abundant and diverse genera with taxonomic and distributional problems. Identification and distribution of species in the Mexican Pacific has been somewhat controversial. Here are provided a large series of new records for Abraliopsis affinis, Abraliopsis falco, Pterygioteuthis gemmata, Pterygioteuthis giardi and Pterygioteuthis hoylei from the Gulf of California and off the SW coast of Mexico. All five species were collected in the central or the southern Gulf of California, or in both. Abraliopsis affinis was found in seven samples with a total of 48 specimens, from 21°59' to 24°53'12"N. Abraliopsis falco was much less represented in the samples (14 specimens) but it was found in 10 localities, four of which correspond to the central-southern Gulf of California (north to 27°44'53"N) and six to SW Mexico (south to 16°49'18"N). In the case of Pterygioteuthis gemmata, only two records (three specimens) were obtained, both in the SW Gulf of California, while Pterygioteuthis giardi (nine specimens) records were all from the central Gulf of California (27°44'53” to 25°39'59"N). In the case of Pterygioteuthis hoylei (nine specimens), material was obtained in six localities, also in a restricted latitudinal range (24°23'48” to 25°56'56"N). PMID:26798236