The Laboratory Population Ecology of Kerona Pediculus (O.F.M.) Epizoic on Hydra SPP.

Abstract

In attempt to determine the factors regulating the distribution and abundance of Kerona pediculus, populations of the hypotrich and hydras were raised in the laboratory in artificial pond water. Factors governing the survival of hypotrichs on hydras were examined by varying the feeding conditions of hydras and the relative numbers available to Kerona. Ciliate populations did not maintain themselves on starved hydras. Availability of undetermined food substances from the hydras seems to limit the numbers of Kerona per hydra. The rate of increase of the hypotrichs varied inversely with density per hydra over a wide range. The densities ranged from below normal (3) to extremely crowded (96). Kerona densities increased in abnormal ways when hydras were infested with Hydramoeba hydroxena, or small histiophagic ciliates and flagellates. Only the amoebic infestation increased the absolute numbers of hypotrichs. Under certain culture conditions in the laboratory, the growth—rate of hydras was greater in the presence of Kerona than in its absence.

A review of the methods used to induce cancer in invertebrates to study its effects on the evolution of species and ecosystem functioning

“…From an ecological perspective, hydras are involved in a variety of interactions with invertebrates and vertebrates. They can, for instance, serve as hosts for commensal (Coleman, 1966) or parasitic species (Stiven, 1965). They are also predators of various zooplankton species, aquatic insect larvae and even fish spawn (Elliott et al, 1997; Rivera‐De la Parra et al, 2016), and are themselves prey for fish or molluscs grazing on plants (Baumgärtner & Rothhaupt, 2005; Cuker & Mozley, 1981).…”

Hydra-Amoeba system: a double infection with a lethal ending

“…The best known are with Kerona pediculus and Trichodina pediculus (Ehrenberg 1838). Both protozoa appear not to damage polyps even when they are present in large numbers (Cavallini 1930, Coleman 1966. Rarer still are those phoretic relationships, such as those described by Stoks & De Bruin (1996) between H. viridis and Anax imperator; the report of Grabow & Martens (2000) between Hydra spp.…”

Cancer and One Health: tumor-bearing individuals can act as super spreaders of symbionts in communities

“…budding) (Domazet-Lošo et al , 2014) (see Figure 1A and 1B). These hydras, as well as other hydra species, are sometimes colonized by the ciliate Kerona pediculus , described as a commensal species (Coleman, 1966;Warren and Robson, 1998) (see however (Stiven, 1983))(see Figure 1C). These unicellular organisms live on the ectoderm of hydra and feed on cellular waste and leftover food.…”