Two Sea Slugs (Nudibranchs) - Aplysia extraordinaria

I photographed these strange and wonderful animals from the main wharf in very low light just after sunset.
I was so intrigued by them that I contacted the Museums Victoria Public Information team to have them identified.

This was the Nudibranch expert's reply:

"The specimen in the images are most likely Aplysia extraordinaria. Victoria has approx. 4 species of Aplysia, none of which swim.
Since this specimen in the image is a swimmer, the most likely candidate is Aplysia extraordinaria.
Interestingly A. extraordinaria is generally more yellowish in colour. (all other diagnostic characters are consistent with that of A. extraordinaria.)
This species is a tropical/sub-tropical species and generally found along the NSW coast, occasionally extending into far eastern Victoria.

See following link for more info. http://www.seaslugforum.net/find/aplyextr

We hope you find this information useful. Please don’t hesitate to contact us if you have any further queries."