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Estimates of biomass are essential for studies modeling the structure, animal growth, production, and energy flow in ecosystems.
The relationships between dry weight and carapace width of two varunid crab species in two different populations were examined.
Distribution of the length-weight plots did not show remarkable differences between species, sexes, and populations. Our results
suggest that length-weight relationships, regardless of sex or population or including multiple species, are valid for estimation
of dry weight. 相似文献
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Bo-Ping Tang Yu Liu Zhao-Zhe Xin Dai-Zhen Zhang Zheng-Fei Wang Xiao-Yu Zhu Ying Wang Hua-Bin Zhang Chun-Lin Zhou Xin-Yue Chai Qiu-Ning Liu 《Genomics》2018,110(4):221-230
The mitochondrial genome (mitogenome) provides important information for phylogenetic analysis and understanding evolutionary origins. Herein, we sequenced, annotated, and characterised the mitogenome of the crab Helice wuana to better understand its molecular evolution and phylogeny. The 16,359 bp mitogenome includes 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes and one control region. The genome composition is highly A + T biased 68.42%, and exhibits a negative AT–skew (? 0.036) and GC–skew (? 0.269) among Brachyura crabs. Gene rearrangements were detected, as was tandem duplication followed by random loss, which explains the translocation of mitochondrial genes. Phylogenetic analysis showed that H. wuana and H. tientsinensis clustered on one branch with high nodal support values. These results confirm that the placement of H. wuana within the Varunidae family of Thoracotrematan crabs. This study will provided a better understanding for gene rearrangements and crab evolution in the further. 相似文献
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Klaus Anger Eduardo Spivak Tomás Luppi Claudia Bas Deborah Ismael 《Helgoland Marine Research》2008,62(2):93-102
The semiterrestrial crab Neohelice (=Chasmagnathus) granulata (Dana 1851) is a predominant species in brackish salt marshes, mangroves and estuaries. Its larvae are exported towards coastal
marine waters. In order to estimate the limits of salinity tolerance constraining larval retention in estuarine habitats,
we exposed in laboratory experiments freshly hatched zoeae to six different salinities (5–32‰). At 5‰, the larvae survived
for a maximum of 2 weeks, reaching only exceptionally the second zoeal stage, while 38% survived to the megalopa stage at
10‰. Shortest development and negligible mortality occurred at all higher salt concentrations. These observations show that
the larvae of N. granulata can tolerate a retention in the mesohaline reaches of estuaries, with a lower limit of ca. 10–15‰. Maximum survival at 25‰ suggests that polyhaline conditions rather than an export to oceanic waters are optimal for
successful larval development of this species. In another experiment, we tested the capability of the last zoeal stage (IV)
for reimmigration from coastal marine into brackish waters. Stepwise reductions of salinity during this stage allowed for
moulting to the megalopa at 4–10‰. Although survival was at these conditions reduced and development delayed, these results
suggest that already the zoea-IV stage is able to initiate the reimmigration into estuaries. After further salinity reduction,
megalopae survived in this experiment for up to >3 weeks in freshwater, without moulting to juvenile crabs. In a similar experiment
starting from the megalopa stage, successful metamorphosis occurred at 4–10‰, and juvenile growth continued in freshwater.
Although these juvenile crabs showed significantly enhanced mortality and smaller carapace width compared to a seawater control,
our results show that the late larval and early juvenile stages of N. granulata are well adapted for successful recruitment in brackish and even limnetic habitats. 相似文献
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Orcovita miruku, new species, is described from Ishigaki Island, southern Ryukyu Islands, Japan. Orcovita miruku is easily distinguished from the other congeners by the presence of three teeth (including external orbital angle) on the
anterolateral margin of the carapace. Orcovita angulata may be allied to O. miruku, but there are a number of differences in the characters of the carapace and the ambulatory legs. The holotype, obtained
from an anchiline pool in a limestone excavation, is the only specimen collected thus far, and this is the first record of
an anchiline crab from Japan. 相似文献
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The larval development of three crabs of the Varunidae family, (Hemigrapsus sanguineus, H. penicillatus, and H. longitarsis), widely spread in Russian waters of the Sea of Japan, were studied under laboratory conditions. At a temperature of 20–22°C and a salinity of 32‰ about 30% of larvae a complete developmental cycle, including five zoeal stages and megalopa, took from 22 to 30 days. All larval stages are illustrated and described in detail. Zoea I and zoea II of the studied crabs are not distinguishable. Zoea III–V of these species differ in the number of dorsomedial setae on the abdominal somite I and in the number of setae on the posterodorsal arch. The megalopae of three Hemigrapsus species possess a different number of segments, aesthetascs and setae on the antennular exopod. In spite of the great similarity of larvae of genera Hemigrapsus and Eriocheir, the latter possesses a number of distinctive features in all developmental stages, supporting the separation of these genera. 相似文献
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