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Reproduction and dispersal

Asexual reproduction

Statoblast dormancy is broken when favourable conditions return - light and warmth promote the release of a single zooid that establishes a new colony via budding (a form of asexual reproduction).

All subsequent zooids in a colony result from budding and are genetically identical, physiologically connected modules.

Asexual reproduction via colony growth, fission and statoblast production is the main mode of reproduction.

Sexual reproduction

Colonies are hermaphroditic and embryos are brooded. A ciliated larva is released and swims for a few hours before settling and metamorphosing into a small colony (Wood & Okamura 2005).

Typically only a low proportion of colonies in local populations undertake sexual reproduction (Uotila & Jokela 1995; Okamura 1997). At least some larvae are products of outcrossing (Freeland et al. 2003).

Dispersal

Statoblasts have spines with hooked tips and can attach to feathers and fur (Bilton et al. 2001). They are highly resistant and achieve dispersal in time and space.

Waterfowl appear to be important dispersal vectors. This is supported by:

  • evidence for waterfowl-mediated gene flow (Freeland et al. 2000a; Figuerola et al. 2005)
  • the presence of statoblasts in waterfowl digestive tracts (Mouronval et al. 2007)
  • viability of statoblasts after passing through duck digestive tracts (Charalambidou et al. 2003)

Limited within-site dispersal is achieved by larvae, and very localised dispersal by colony movement.

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