文摘
Morphological, distributional and behavioural patterns indicate that members of the Heterophyidae have a soldier caste. A soldier caste is present in at least two superfamilies of the Trematoda: Echinostomatoidea and Opisthorchioidea. A non-reproductive soldier caste is present in species that are lower in dominance hierarchies than previously known. Developing infections are dominated by immature reproductives, and characterised by unimodal size-frequency distributions. The size-frequency distributions become more bimodal as the colony ages.