Decoy defence

Subject: Decoy defense. It took us a while before we could name this misleading stranger. Ceratophyllidia (sp? 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. Ceratophyllidia (sp? ,africana?) uses autotomy as a survival strategy.

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 Nudibranchs as well as 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 lizard’s tail.

Technique: While filming this strange looking nudibranch in Bali/Indonesia the animal suddenly started to loose almost all of the papillae when I repositioned myself. Unfortunately the shedding itself, which happened in less than a second or so, was not caught on camera. Probably I came too close with my camera’s dome for the little nudibranch’s comfort. We often do not keep the record button pushed in long enough to catch the image of a lifetime. Be patient, continue to film and expect the unexpected to happen.

All images Copyright 2020 Olivier Van den Broeck and Greet Meulepas for Beyond scuba. All rights reserved.