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1.
The feeding habits of the filter-feeding fairy shrimp Streptocephalus proboscideus are documented experimentally by offering them ciliates, Volvox, rotifers, nematodes and small crustaceans as prey. Escape capabilities (e.g. swimming speed) rather than size or shape were found to determine these animals' vulnerability to predation by the fairy shrimp. Ingestion rates for Volvox increased hyperbolically with size and, at the high temperatures in which they live, fairy shrimps may daily remove the equivalent of their body weight from the environment.  相似文献   
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The species Branchinecta granulosa Daday 1902, is redescribed on the basis of adult material from near Facundo (Chubut Province, Argentina). Its relationship to its regional congeners is outlined.  相似文献   
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Cyst hatching, under standardized conditions, of the Anostracan species Thamnocephalus platyurus and Streptocephalus dichotomus was significantly accelerated but not increased by applying the morphogen retinoic acid (RA). Cyst hatching was enhanced but not accelerated by artificially increasing the inflow of Ca2+ to the embryonic cells, using Calcium Ionophore A 23 187. Cyst hatching was accelerated and amplified, to a level in excess of the summed effects of each treatment, by a combined application of RA and ionophore. It was inhibited almost quantitatively by the Calcium-channel blockers Nifedipin and Verapamil. The significance of these findings is discussed.  相似文献   
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The shape of the resting eggs of a large branchiopod crustacean, the Anostraca Tanymastix stagnalis , is represented very accurately by analytical expressions. The occurrence of atypical shape of some T. stagnalis eggs may be viewed as a simple change of the analytical expression describing the usual egg shape. Their unusual shape may be explained by a higher embryo volume within an envelope of a given size. Biological implications are briefly discussed and hypothesized in an evolutionary point of view.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 55–60.  相似文献   
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The nuclear small subunit ribosomal DNA (18S rDNA) of 27 anostracans (Branchiopoda: Anostraca) belonging to 14 genera and eight out of nine traditionally recognized families has been sequenced and used for phylogenetic analysis. The 18S rDNA phylogeny shows that the anostracans are monophyletic. The taxa under examination form two clades of subordinal level and eight clades of family level. Two families the Polyartemiidae and Linderiellidae are suppressed and merged with the Chirocephalidae, of which together they form a subfamily. In contrast, the Parartemiinae are removed from the Branchipodidae, raised to family level (Parartemiidae) and cluster as a sister group to the Artemiidae in a clade defined here as the Artemiina (new suborder). A number of morphological traits support this new suborder. The Branchipodidae are separated into two families, the Branchipodidae and Tanymastigidae (new family). The relationship between Dendrocephalus and Thamnocephalus requires further study and needs the addition of Branchinella sequences to decide whether the Thamnocephalidae are monophyletic. Surprisingly, Polyartemiella hazeni and Polyartemia forcipata ("Family" Polyartemiidae), with 17 and 19 thoracic segments and pairs of trunk limb as opposed to all other anostracans with only 11 pairs, do not cluster but are separated by Linderiella santarosae ("Family" Linderiellidae), which has 11 pairs of trunk limbs. All appear to be part of the Chirocephalidae and share one morphological character: double pre-epipodites on at least part of their legs. That Linderiella is part of the Polyartemiinae suggests that multiplication of the number of limbs occurred once, but was lost again in Linderiella. Within Chirocephalidae, we found two further clades, the Eubranchipus-Pristicephalus clade and the Chirocephalus clade. Pristicephalus is reinstated as a genus.  相似文献   
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Sarma  S. S. S.  Nandini  S. 《Hydrobiologia》2002,486(1):169-174
Freshwater cladocerans and rotifers were used as prey to study functional response and prey selection by adult females of Chirocephalus diaphanus under laboratory conditions. For functional response studies, we offered three rotifer species (Brachionus calyciflorus, B. patulus and Euchlanis dilatata) and three cladoceran species (Alona rectangula, Ceriodaphnia dubia and Moina macrocopa) at various densities ranging from 0.5 to 16 ind. ml–1. We found increased zooplankton consumption with increasing prey density but beyond 4 ind ml–1 cladocerans and 8 ind. ml–1 rotifers, the number of animals eaten plateaued. In general, C. diaphanus consumed fewer large prey (cladocerans) and many more smaller zooplankton (rotifers). For prey selection experiments, we used B. calyciflrous, B. patulus, C. dubia and M. macrocopa, offered at the ratio of two rotifers: one cladoceran and at three prey densities (total zooplankton numbers: 3, 6 and 12 ind. ml–1). Prey selectivity patterns followed the functional response trends. In general, regardless of prey types, with an increase in the available zooplankton, there was an increase in the number of prey consumed. At any given prey density, C. diaphanus consumed higher numbers of rotifers than cladocerans. Among the prey offered, B. patulus and M. macrocopa were positively selected. Results are discussed in light of possible control of zooplankton by anostracans in temporary ponds.  相似文献   
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Tanymastix stagnalis is known from seven locations in Ireland. These range from small to large temporary water bodies. It was earlier shown that the best hatching and survival of eggs and young stages occurred in the presence of soil and at temperatures between about 10° and 15°. Some eggs hatched after one drying period, others after up to at least 4 drying and wetting periods. It was found from field observations that the habitat appeared after a minimum of 200 mm of rain in a 2-month period. This occurred on average more than once per year, mostly between June and February. A computer model was constructed using field data, and meteorological data (rainfall and temperature) covering 100 years, to decide how secure the organism was in two contrasting habitats. This showed that in both habitats there was little likelihood of extinction from metorological causes. There was, however, the possibility of destruction of the smaller habitats either through drainage or conversion to permanent ponds through compaction of the soil by heavy farm animals. The distribution and the possibility of harvesting the organisms is briefly discussed.  相似文献   
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The surface topography and layering of the cyst wall of the fairy shrimps Streptocephalus dichotomus, S. torvicornis and Thamnocephalus platyurus are described, based on scanning electron micrographs. Cyst walls are not invariably bilayered, but may be composed of up to four layers. They are species-specific in all taxa so far studied. Cyst wall structure within single cysts may differ according to the topographical location on the cyst.  相似文献   
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