نتایج جستجو برای: ctenophora
تعداد نتایج: 318 فیلتر نتایج به سال:
Despite expanding data sets and advances in phylogenomic methods, deep-level metazoan relationships remain highly controversial. Recent phylogenomic analyses depart from classical concepts in recovering ctenophores as the earliest branching metazoan taxon and propose a sister-group relationship between sponges and cnidarians (e.g., Dunn CW, Hejnol A, Matus DQ, et al. (18 co-authors). 2008. Broa...
The origin of many of the defining features of animal body plans, such as symmetry, nervous system, and the mesoderm, remains shrouded in mystery because of major uncertainty regarding the emergence order of the early branching taxa: the sponge groups, ctenophores, placozoans, cnidarians, and bilaterians. The "phylogenomic" approach [1] has recently provided a robust picture for intrabilaterian...
The suprabenthos or hyperbenthos is the macrofaunal assemblage of small-sized organisms that interact for some time in the benthic boundary layer. Information about the taxonomic composition and role of suprabenthic species, especially in littoral zones, is scarce and scattered. This work attempts to contribute alleviate this problem. We analyze the temporal and spatial variations of suprabenth...
Observations of ctenophore species were made in the Gulf of Trieste between 2003 and 2006. We examined native ctenophore species with special attention to representatives of the orders Lobata and Beroida, and we recorded among them two non-native ctenophores: Mnemiopsis leidyi A. Agassiz 1865 and Beroe ovata sensu Mayer, 1912. The validity of the Mediterranean species Beroe ovata is discussed. ...
Metacercaria specimens of the genus Opechona (Trematoda: Digenea: Lepocreadiidae) are described parasitizing “coelenterates” (scyphomedusae and ctenophores) from Southeastern Brazil (São Paulo state). The worms are compared to other Opechona species occurring on the Brazilian coast, but no association has been made because only adult forms of these species have been described. Suppositions as t...
Euplokamis has coiled tentilla on its tentacles, which can be discharged, flicking out at high velocity, when triggered by contact with prey. The tentillum adheres to prey by means of numerous colloblasts. Discharge, which takes 40-60 ms, is accomplished by contraction of striated muscles, found only in this genus among the Ctenophora. Restoration of the coiled state is attributable to passive,...
Abstract Jellyfish are important components of the marine ecosystem and present a potential resource for different economic domains (e.g. medicine, food biotechnology). We an overview current state jellyfish biodiversity in Macaronesia region, which includes archipelagos Azores, Madeira, Canary Islands Cape Verde, examine possible biogeography patterns among its archipelagos. Based on comprehen...
As naval operations move into coastal waters, the possible impact of sporadic blooms of bioluminescent organisms on clandestine operations is of increasing concern. One such bloom forming light producer is the ctenophore Mnemiopsis leidyi. This native-American comb jelly was first introduced into the Black Sea in 1982 where it caused the total collapse of the local fisheries. It has recently b...
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