Sample records for aschelminthes
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Winnepenninckx, B; Backeljau, T; Mackey, L Y; Brooks, J M; De Wachter, R; Kumar, S; Garey, J R
1995-11-01
The Aschelminthes is a collection of at least eight animal phyla, historically grouped together because the absence of a true body cavity was perceived as a pseudocoelom. Analyses of 18S rRNA sequences from six Aschelminth phyla (including four previously unpublished sequences) support polyphyly for the Aschelminthes. At least three distinct groups of Aschelminthes were detected: the Priapulida among the protostomes, the Rotifera-Acanthocephala as a sister group to the protostomes, and the Nematoda as a basal group to the triploblastic Eumetazoa.
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Shapeero, W L
1961-03-24
The systematic position of the small invertebrate group, Priapulida, is uncertain. In more recent publications they are classified usually as pseudocoelomates in the division Aschelminthes. A histological investigation of Priapulus caudatus, a widely distributed species, reveals the body cavity to be a coelom, its lining a peritoneum. These features, and others, indicate the priapulids to be. coelomates rather than pseudocoelomates. Unique morphology perhaps qualifies the group for the status of phylum.
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A new Aschelminth, probably related to the Priapulida
Land, van der J.
1968-01-01
INTRODUCTION Two years ago I found two specimens of a curious animal in a sample of coral sand from Curaçao. It superficially resembled the larva of priapulids, animals that are restricted to cold water. The condition of the specimens did not permit of a description and I did not succeed in
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An introduction to loricifera, cycliophora, and micrognathozoa.
Kristensen, Reinhardt Møbjerg
2002-07-01
Loriciferans, cycliophorans and micrognathozoans are amongst the latest groups of animals to be discovered. Other than all being microscopic, they have very different body plans and are not closely related. Loriciferans were originally assigned to the Aschelminthes. However, both new molecular and ultrastructural researches have shown that Aschelminthes consist of two unrelated groups, Cycloneuralia and Gnathifera. Cycloneuralia may be included in the Ecdysozoa, including all molting invertebrates, and Gnathifera are more closely related to Platyhelminthes. The phylum Loricifera shares many apomorphic characters (e.g., scalids on the introvert) with both Priapulida and Kinorhyncha, and can be included in the taxon Scalidophora, a subgroup of Cycloneuralia. Cycliophora was originally allied to the Entoprocta and Ectoprocta (Bryozoa) based on ultrastructual research. Subsequent molecular data show they may be related to Rotifera and Acanthocephala, within the taxon Gnathifera. The phylogenetic position of Cycliophora is therefore not settled, and more ultrastructural and molecular data are needed. Micrognathozoa is the most recent major group of animals to be described. They show strong affinities with both Rotifera and Gnathostomulida (within the taxon Gnathifera), especially in the fine structure of the pharyngeal apparatus, where the jaw elements have cuticular rods with osmiophilic cores. Furthermore the micrognathozoans have two rows of multiciliated cells that form a locomotory organ, similar to that seen in some gastrotrichs and interstitial annelids. This character is never seen in Rotifera or in the monociliated Gnathostomulida. Rotifera and Acanthocephala always have a syncytial epidermis (Syndermata). Micrognathozoa lack this characteristic feature. Therefore, they are postulated to be placed basally in the Gnathifera, either as a sister-group to Gnathostomulida or as a sister-group to Rotifera + Acanthocephala.
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Keshmirian, J; Nogrady, T
1988-01-01
1. Catecholaminergic structures in the male Brachionus plicatilis were investigated, using aqueous dansylpropranolol as fluorescent label of neurotransmitter receptors. 2. All major organs of the male are innervated by catecholaminergic systems, that may also be involved in the regulation of copulatory behavior. 3. Cryostat-sectioned preparations of the female B. plicatilis were also investigated. They provided additional information to findings on whole animals reported in our previous paper (Keshmirian and Nogrady 1987 a).