Spongiobranchaea australis  d'Orbigny, 1834

Click the thumbnail photos to enhance!

Spongiobranchaea australis is part of a larger group which is commonly known as the sea butterflies because they swim by flapping what appear to be small "wings". This common name is used for planktonic sea slugs that is the phytoplankton-feeding, shelled Thecosomata and the carnivorous, unshelled Gymnosomata, though there is no close evolutionary relationship between them.
Gymnosome pteropods are highly specialised sea slugs which spend their whole lives in the plankton. They have a pair of wing-like paddles which are used for swimming and by a 'sculling' movement are able to propel the animal quite quickly. As well as being built for swimming, gymnosomes are also built for hunting. They all have very elaborate foreguts with a proboscis, entrapping tentacles and cutting radular teeth.
The above specimen was identified by Daniel Oscar Forcelli on the facebook group ID Please (Marine Creature Identification), thanks!
The specimen seems to be spawning, the eggs embedded a gelatinous blob.
A description of Spongiobranchaea australis is on
How to cite:
Köhler, E. (2016), published 27 July 2016, Spongiobranchaea australis  d'Orbigny, 1834
available from http://www.Philippine-Sea-Slugs.com/Gymnosomata/Spongiobranchaea_australis.htm