Biology of Symbiotic Apostome Ciliates: Their Diversity and Importance in the Aquatic Ecosystems

Genetic analysis of ciliates living on the groundwater amphipod Crangonyx islandicus (Amphipoda: Crangonyctidae)

“…In a study on estuarine shrimp by Landers (1986), phoronts were mainly found under the branchiostegite and on the antennal plates of the host while Ohtsuka et al (2004) documented phoronts of the species Vampyrophrya pelagica mainly on swimming legs and ventral side of the prosoma of the copepod hosts. Ohtsuka et al (2015) suggested that the feeding habit and swimming movement explained the attachment sites of the phoronts on the copepods and the same might apply for the amphipods as they create a water current passing their antenna and flowing through their branchial chamber between the coxal plates where gills and eggs are found. This current is generated with the pleopods to facilitate respiration (Dahl, 1977).…”

“…Comparisons of the results of morphological and molecular data linked the oval-shaped structures with phoronts, an encysted stage, known from exuviotrophic apostomatid ciliates which are frequently found in association with crustacean hosts (Lynn, 2008;Ohtsuka et al, 2015), feeding on exuvial fluid within the freshly moulted exoskeleton of their host (Chatton & Lwoff, 1935).…”

“…These genera are mainly found in the marine environment as exuviotrophs and histotrophs on crustacean hosts although some are found in freshwater (Ohtsuka et al, 2015). Among the apostomatids, the closest relatives are from the Foettingeriidea family, including the genera Gymnodinioides, Hyalophysa, Synophrya and Vampyrophrya.…”

“…Among the apostomatids, the closest relatives are from the Foettingeriidea family, including the genera Gymnodinioides, Hyalophysa, Synophrya and Vampyrophrya. These genera are mainly found in the marine environment as exuviotrophs and histotrophs on crustacean hosts although some are found in freshwater (Ohtsuka et al, 2015). They form phoronts on the surface of their host although they differ in nature between genera (Bradbury, 1974;Landers, 2010a;Landers, Gómez-Gutiérrez, & Peterson, 2007;Ohtsuka et al, 2004).…”

“…Studies on intraspecific genetic diversity of microbial eukaryotes are generally limited (e.g., Gentekaki & Lynn, 2009). Recent work on marine ciliate epibionts has indicated wide occurrence (Guo et al, 2012) and for groups within the order Apostomatida it has been demonstrated for some species that there is some degree of host specificity (Ohtsuka, Suzaki, Kanazawa, & Ando, 2015). As apostome ciliates have a free-swimming stage (the tomites), the ciliates may have a potential for independent dispersion among groundwater springs.…”