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You are here:   OldClasses > 2012 > Pseudoceros prudhoei | Carolina Marques



Pseudoceros prudhoei


Carolina Marques (2012)



Fact Sheet



Physical Description


Life History & Behaviour

Anatomy & Physiology

Evolution & Systematics

Biogeographic Distribution

Conservation & Threats

References & Links

Life History & Behaviour

Swimming Behaviour: While some of the free-living flatworms tend to hide under rocks escaping from the sunlight, colorful polyclads usually demonstrate a very conspicuous behaviour, swimming through the water column next to coral reefs.These animals actually do not need to avoid predators, because their bright colour pattern works as a warning sign about their distastefulness and toxicity (Ang and Newman, 1998).


A very simple experiment was conducted at Heron Island Research Station in September of 2012 during a field trip to test this exhibitionist behaviour for Pseudoceros prudhoei. Four individuals of the species were collected at the lagoon and placed at appropriate tanks at the research station (Fig. 4). The experiment was conducted in a dark place and the worms were handled with care to avoid deterioration, as these animals are extremely fragile. The individuals were put, one at a time, in a small tank with rocks at one end and a flashlight at the other. The flashlight was turned on and they were given 10 minutes to react. Then, they were placed in the dark again to rest for 30 minutes. This method was repeated three times.

Figure 4. Map of Heron Island indicating the site where the animals were collected.


None of the animals had a negative response to the presence of light. When the flashlight was turned on, they started swimming around and exploring the environment and none of the worms hid under the rocks searching for cover. In fact, the light didn’t seem to bother them at all, as some would swim toward it, swim back and settle down at any spot (Video 1). This result suggests that P. prudhoei is not negatively phototactic and reinforce the function of aposematic coloration in pseudocerotids.



Reproduction: Polyclads are hermaphrodites and reproduce by internal fertilization. There are two methods of copulation: the first one is a reciprocal transfer of sperm to the female pore, and the second one is called “penis fencing”, which is common between the pseudocerotids. Basically, the worms stab their partners and inject sperm through the body wall while trying to avoid getting stabbed.  They probably do that because being a father is a more effective and less energy demanding way of dispersing genetic material than being a mother (Newman and Cannon, 2003) (See suggested links).



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