Nudibranchs Pleurobranchus and Flabellina are chalk and cheese!

First up an example of the Pleurobranchus group called Weberi.

These monster nudibranchs that can, depending the individual, grow to a max of 30 centimetres, usually these guys feed on ascidians, though if need be they will consume other life forms.
Okay lets say this one is the chalk.  


The next is an example of the group being Flabellina of the family Aeolids.
The actual one I cant find its individual name, but they feed on hydroids usually called Eudendrium ramosum and these stingers, for us diver as well and not just marine life, contain a pigment called astaxanthin, this gives the Flabellina nudibranch its brilliant coloration.
This little guy of just 6 mill in length featured, is most certainly the cheese out of these two!