Decoy Defence16 March 2017
It took us a while before we could name this misleading stranger. Ceratophyllidia africana* is its name, deception its specialty! Since many Opisthobranchs evolved into shell-less creatures they had to come up with new ways to defend themselves: Some have tough skin or protective appendages, others secrete chemicals or use stinging cells gained from their food source, some show off warning behaviour, expel ink or flash light while others just swim away. As a survival strategy C. africana uses autotomy. The word autotomy comes from Greek and means self-severing. This little nudibranch shed its bubbles or papillae the moment it felt threatened by the movement of the camera. The rolling bubbles intent to distract a predator thus giving the snail a chance to hit the road. The papillae grow back from the numerous tubercles covering its body. Relatively many Opisthobranchs use autotomy: it occurs in all suborders of the Nudibranchia as well in de order of the sap-sucking slugs (Sacoglossa) and the order of the side-gill slugs (Notaspidae). The body parts that are sacrificed range from pieces of the mantle, some of the cerata, parts of the gills, the tail and the parapodial lobes. Sometimes a sticky secretion emitting an aromatic scent accompanies the discarded body parts. Rejected cerata may even squirm and wriggle for a while... just like a shedded lizards tail.
* Since the original article was written in July 2015 scientists have doubts that this Ceratophyllidia species found in Bali is in fact C. africana. There is reason to believe that this find is a complete new species. Further investigation will provide it with a definite name, for now it is called Ceratophyllidia sp.