The representatives of the main phylogenetic clades of Bilateria are characterized by metamery. In Deuterostomia, metamery is presented in hemichordates and chordates. Sea urchins have 7 metameric coelomic rings located along the oral-aboral axis of the body. A similar coelomic metamery is also a sign of representatives of other classes of echinoderms. We hypothesize that the metameric coelomic rings in echinoderms are inherent of the common ancestor of Deuterostomia. Asymmetry in the structure of echinoderm coeloms is the result of ancestral forms lying on the right side of the body, which led to a reduction of the coeloms on the right side. During the sedentary lifestyle, the left-side coeloms formed metameric coelomic rings.
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http://dx.doi.org/10.1134/S0012496621050021 | DOI Listing |
Integr Comp Biol
November 2024
Institute of Cellular and Organismic Biology, Academia Sinica, 11529 Taipei, Taiwan.
Metameric somites are a novel character of chordates with unclear evolutionary origins. In the early branching chordate amphioxus, anterior somites are derived from the paraxial mesodermal cells that bud off the archenteron (i.e.
View Article and Find Full Text PDFIntegr Org Biol
March 2024
Department of Ocean Engineering and Marine Sciences, Florida Institute of Technology, Melbourne, FL 32901-6975, USA.
Animal phyla are distinguished by their body plans, the ways in which their bodies are organized. A distinction is made, for example, among phyla with bodies of many segments (metameric; e.g.
View Article and Find Full Text PDFJ Morphol
August 2023
Laboratorio de Ecotoxicología Acuática, DBBE and IBBEA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Ciudad Autónoma de Buenos Aires, Argentina.
Among anurans, Bufonids are recognized for their retarded sex differentiation. However, few studies have addressed gonadal morphogenesis in this family. Here, we analyzed the early gonadogenesis in laboratory-reared Rhinella arenarum.
View Article and Find Full Text PDFJ Parasitol
March 2023
Hawaii Division of Aquatic Resources, Department of Land and Natural Resource, State of Hawaii, 75 Aupuni Street, Room 204, Hilo, Hawaii 96720.
Pterobdella occidentalis n. sp. (Hirudinida: Piscicolidae) is described from the longjaw mudsucker, Gillichthys mirabilis Cooper, 1864, and the staghorn sculpin, Leptocottus armatus Girard, 1854, in the eastern Pacific, and the diagnosis of Pterobdella abditovesiculata (Moore, 1952) from the 'o'opu 'akupa, Eleotris sandwicensis Vaillant and Sauvage, 1875, from Hawaii is amended.
View Article and Find Full Text PDFDokl Biol Sci
November 2021
Biological Faculty, Moscow State University, 119991, Moscow, Russia.
The representatives of the main phylogenetic clades of Bilateria are characterized by metamery. In Deuterostomia, metamery is presented in hemichordates and chordates. Sea urchins have 7 metameric coelomic rings located along the oral-aboral axis of the body.
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