Zool 250
Best Annotated Bibliography 2002
Submitted by Sylvie Tissander

Ang, H.P. and L. J. Newman. 1998. Warning coloration in pseudocerotid flatworms (Platyhelminthes, Polycladida) Hydrobiologia 383: 29-33.

Pseudoceros flatworms are known for their colorful pigmentation and conspicuous behavior, typical of an animal displaying aposematic coloration. But as the toxicity of these flatworms remains unstudied until now, the question remains as to whether this flatworm is a Batesian or a Mullerian mimic.

An animal that is a Batesian mimic is benign and mimics the color pattern and/or shape of an animal that is toxic. Predators learn to avoid the specific color patterns of unpalatable animals, thus benefiting the mimic. In Mullerian mimicry, several animals display a similar color pattern and shape, and are all toxic.

To test this mimicry, Ang and Newman placed brightly colored flatworms, dull colored flatworms and synthetic replicas of each in aquaruim tanks with fish that are known predators of flatworms. The number of flatworms and their replicas damaged by fish was recorded.

Results showed that while there was no significant difference between the number of live latworms and synthetic replicas attacked, there was, however, a difference in the number of attacks on differently colored flatworms. The flatworms displaying bright color pattern and conspicuous behavior were attacked significantly less than those with dull coloration. Often fish were recorded attempting to ingest and then rejecting the colorful flatworms. This leads the scientists to the conclusions that pseudocerotid flatworms use not only warning coloration, but also a toxic repelling element to avoid predation. The presence of toxic elements means that Pseudoceros is a Mullerian mimic.

(241 words)

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(posted Jan. 2003)