Phil Garner recently sent in images of Ceratosoma brevicaudatum . C. brevicaudatum has been done before on the site but how could we not showcase the extraordinary images taken by Phil on a recent trip to South Australia with Merry Passage. C. brevicaudatum (Bill Rudman's Sea Slug Forum) was easily the most common nudibranch Jim Black and I saw on a 2014 trip to South Australia. This species is readily identified by the red "horn" like appendage in the tail area as seen in the photo to the left.

The following is a discussion of this odd dorsal "horn" by Bill Rudman on his Sea Slug Forum

"... Ceratosoma trilobatum usually have a long recurved dorsal 'horn' which sticks up from the body behind the gills. This horn has an interesting defensive function because it is where the animal stores distasteful and noxious chemicals its has removed from its sponge food. The horn appears to act as a sacrificial lure, tempting fish to take a bite. When or if they do they get a mouth full of nasty chemicals which teach them to leave Ceratosoma alone. As the 'hom' has no other function, the slug can live quite happily without it. It seems that Ceratosoma brevicaudatum represents an early stage in the evolution of the dorsal horn. In the close-up alongside I have ringed the swollen 'bump' which is found in this species. It is packed full of noxious chemicals and is usually more brightly coloured thyan the rest of the body - again acting as a lure. If you look at some of the other messages on this species, which are attached to the Fact Sheet, you will see that in juveniles the horn is even more brightly coloured. The name brevicaudatum means 'short tail' in Latin, which is a reference to this very short dorsal horn..."

One has to say again, isn't nature absolutely amazing!

Phil Shoots with a Nikon D850 with a 60mm lens.

Send Phil email at pacificcoast101@yahoo.com
Send Merry email at mbpassage@yahoo.com