University of Adelaide research into parasites of cuttlefish, squid and octopus has uncovered details of the parasites' astonishing life cycles, and shown how they may help in investigating populations of their hosts.
Researcher Dr Sarah Catalano has described 10 new parasite species− dicyemid mesozoans −, which live in the kidneys of cephalopods (cuttlefish, squid and octopus). They are the very first dicyemid species to be described from Australian waters.
"Although dicyemid parasites have been studied by other groups, nothing has been known about dicyemid fauna and infection patterns from Australian waters," says Dr Catalano, who this month will graduate with her PhD from the University's School of Earth and Environmental Sciences. She will continue her work at the South Australian Museum.
The dicyemid parasites are tiny organisms, simple in appearance and made up of only 8-40 cells without any obvious tissue structure but they do have surprisingly complex life cycles. They exist in two forms: adults are long and slender whereas embryos can be a clone of the adult only smaller, or have a distinctive circular form. They also have two modes of reproduction sexual and asexual.
"Surprisingly, we found that the left and right kidneys of a single host individual were infected independently of each other, with one kidney infected by asexual forms and the other by sexual forms, suggesting this mechanism is parasite-controlled not host-mediated," says Dr Catalano. This finding has been published in the journal Folia Parasitologica.
"To make their life cycle that much more complex, these parasites are also highly host-species specific. To infect a new host, the circular embryo form of the parasite is released with the host's urine out into the sea. It then has to find a new squid or cuttlefish or octopus individual that is of the right species within a limited time-frame before it perishes, while
|Contact: Dr. Sarah Catalano|
University of Adelaide