Phylum Rotifera comprises 1800 species of microscopic metazoans (80-20001am in length) divided into three major groups: Monogononta (-1450 species), Bdelloidea (-350) and Seisonidea (2) (Segers, 2002). They are characterized by short life cycle and direct development, most are filter-feeders, some are predators and few live as parasites. The three groups differ because of their reproduction. Seisonids are always amphimictic, with sex ratio 1:1, and monogononts punctuate thelytokous parthenogenesis (producing females) with arrhenotokous parthenogenesis (producing males) and subsequent sexual reproduction. Mating produces a diploid egg with delayed development, called resting egg; however, among most monogonont species only females are known so far. Bdelloids consist of parthenogenetic females only (Mark Welch and Meselson, 2000). Monogononts live in aquatic habitats like rivers, lakes, ponds, temporary and permanent pools, lagoons and seas, and very few can live in the water films around soil particles (Nogrady et al., 1993). Bdelloids are commonly part of the meiofauna of any habitat where water is occasionally present, thus they can be found in rivers, lakes, ponds, but also among soil particles, and in mosses and lichens (Donner,1965), and almost all of them can escape unfavorable periods entering anhydrobiosis (Ricci, 2001). Seisonids are exclusively marine (Ricci et al., 1993).
Mediterranean rotifers: a very inconspicuous taxon.
Fontaneto Diego
2003
Abstract
Phylum Rotifera comprises 1800 species of microscopic metazoans (80-20001am in length) divided into three major groups: Monogononta (-1450 species), Bdelloidea (-350) and Seisonidea (2) (Segers, 2002). They are characterized by short life cycle and direct development, most are filter-feeders, some are predators and few live as parasites. The three groups differ because of their reproduction. Seisonids are always amphimictic, with sex ratio 1:1, and monogononts punctuate thelytokous parthenogenesis (producing females) with arrhenotokous parthenogenesis (producing males) and subsequent sexual reproduction. Mating produces a diploid egg with delayed development, called resting egg; however, among most monogonont species only females are known so far. Bdelloids consist of parthenogenetic females only (Mark Welch and Meselson, 2000). Monogononts live in aquatic habitats like rivers, lakes, ponds, temporary and permanent pools, lagoons and seas, and very few can live in the water films around soil particles (Nogrady et al., 1993). Bdelloids are commonly part of the meiofauna of any habitat where water is occasionally present, thus they can be found in rivers, lakes, ponds, but also among soil particles, and in mosses and lichens (Donner,1965), and almost all of them can escape unfavorable periods entering anhydrobiosis (Ricci, 2001). Seisonids are exclusively marine (Ricci et al., 1993).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
