The Hidden World of Parasites

Prof. Beth Okamura will talk about the challenges in understanding parasite diversity, life history, distribution, and evolution.

Parasites are ubiquitous and diverse. Most, however, are hidden from view, infecting hosts internally as ‘endoparasites’. Recognition of many parasites is therefore challenging and hinders understanding of parasite diversity, life history, distribution, and evolution.

Recent confirmation that the enigmatic Myxozoa is a large radiation of parasitic cnidarians greatly expands our appreciation of endoparasite diversity and the tree of life, as explored in this talk. Myxozoans infect vertebrate and invertebrate hosts and have long been recognised as parasites of fish. Surprisingly, myxozoan species diversity rivals that of their free-living relatives, and their recognition adds a major dimension to a phylum otherwise primarily composed of carnivorous animals (e.g. sea anemones, jellyfish, and coral). Myxozoans spectacularly illustrate routes from multicellular to unicellular organisation involving miniaturisation, extreme morphological simplification, and unique motilities – pathways all enabled by modification of a basic cnidarian building block (the epitheliomuscular cell). Strategies of host exploitation, resolving the source of an emerging disease of salmon and trout, and contributions of serendipity to research are also highlighted in this talk.