DIVE LOG AUSTRALASIA FEB 2025 ISSUE 410

Swallow-Tailed Sea Slugs

An Assortment of Aglajids - Part 2 Not all of the aglajids have the long tails like most of those presented in Part 1 of this series. The examples shown here in this second part, do have tails, or caudal lobes, but they are of modest size and usually of almost equal length and somewhat paddle-like in presentation. As we move into these other genera the amazing diversity of appearance in this family is revealed. NudiNotes and the NudibranchDomain.org website does not split up Philinopsis into four separate genera as proposed in 2017. The taxonomy of Nudibranchs & Sea Slugs Identification - Indo-Pacific, Gosliner, Valdes & Behrens, 2018 is followed. All of those species still represent a monophyletic group. The separation (splitting) is considered unnecessary and simply adds to confusion. (Note: The sp. numbers refer to species on the NudibranchDomain.org website)

Above: Three presentations of Philinopsis speciosa , a highly variable species in colour and patterning. Most usually with a black background and blue edging, stripes of yellow or orange and sometimes with spots or patches of a lighter shade. Specimens of lighter colouration are known. A distinctive characteristic is the upturned posterior extension of the headshield. It is an aggressive nocturnal hunter of bubble-shell sea slugs.

Above: Two examples of the Odontoglaja genus - Left: Odontoglaja guamensis and Right: Odontoglaja sp. 01 Most aglajids do not possess a radula or gizzard plates however the Odontoglaja are the exception having radula teeth that can secure their prey and a rudimentary gizzard for crushing. Considered to have reached a peak in predatory specialisation in the hunting of highly mobile prey such as polychaete worms, isopods and other sea slugs.

20

DIVE LOG Australasia #410 - February‘25

www.divelog.net.au