Review of nudibranch book(002) by Alan Wiggs

review | book release

NEWNUDIGUIDE Author: Robert Burn

I imagined that reviewing a scientific text would be daunting, but Nudibranchs and related molluscs is nothing like a dry scientific text! Robert Burn has captured the essence of what makes these tiny colourful and cryptic critters so fascinating and appealing to divers. Many of us may pass over nudibranchs on local dives without giving them a passing glance, but others seriously seek out a new discovery to check off a very long list. The southeastern coast of Australia is blessed with an abundance of these often bizarre creatures and many divers will be familiar with some of the specimens identified in the book. But you may only have seen a handful of the 250 species covered in the text. The seemingly infinite variety in colour, shape and form of nudibranchs are well documented, but Robert also examines some of the quirky characteristics that make these ‘butterflies of the sea’ so interesting! It is a case of the deeper you dig, the more you find out about the fascinating world of these creatures. Robert Burn’s book is aimed at amateur naturalists, beachcombers and environmental scientists, but I suspect divers and particularly underwater photographers will pore over these pages and top quality scientific and field images. Glancing over the text, you’ll make amazing discoveries, but be warned – this book will launch you on a quest to seek out more of the little critters!

sportdiving magazine 2016 Issue 171

It commences with detailed coverage of nudibranch characteristics – side-gilled slugs; bubble shells, sea hares; sap-suckers and the delightful ‘sea butterflies’ and soon gets into the bizarre habits of certain species. I thought I knew a bit about nudis, but I realise now I’ve only really begun. Some of their feeding habits are the stuff of horror movies! Take, for instance, the Okeinia rhinorma, that ploughs through the sandy seabed searching for the hapless sand ascidian Mogula. Once it’s located, the Okenia dives under the sand, quietly munches a hole through the ascidians skin and process to eviscerate its food. Nasty! Less spectacular, but with a similar dietary

technique, the sap-suckers or sacoglossan nudibranchs, cut a minute slit in the body wall of algae and suck out the yummy algal sap. Nudibranchs have a host of tricks and adaptations, and the sapsuckers are just one example of various biotic associations described in the text. Not only do the sap suckers consume the algal sap, they’re able to ingest and retain the photosynthetic ‘plastids’ within their own body and ‘cerata’ (the daggy tubular bits!) Effectively they’re now ‘solar powered’ nudibranchs to a degree. Even more bizarre, many of the aeolid nudibranchs prey upon stinging cnidarians (defined as ‘jellyfish, anemones, corals and hydroids’ in the very useful glossary on page 248.) But in the process of consuming them, they somehow or other are able to ingest, process and store the unexploded stinging cells (‘nematocysts’) in special sacs at the tips of their cerata. So we now have a stinging nudibranch that ‘borrowed’ the stinging cells from its prey, keeping them primed and ready for its own use and defence. Amazing! Most divers will be familiar with some of the bright colour combinations of various nudibranch families, particularly the strikingly patterned chromodorid family. These are easily seen as they stand out from their environment and signal their toxicity through such an obvious display. Spots, stripes, elaborate fringes and physical features all shout out “I’m poisonous! Don’t eat me!” Fewer divers

though will have noticed those other nudis that take the opposite approach and depend on subtle concealment through incredible mimicry – often the only giveaway is a pair of tiny rhinophores, the antennae or chemoreceptors with which nudibranchs detect chemical trails and scents in the water. Various families adopt this camouflage – I thought it was big news to find ‘phyllodesmium’ mimic nudibranchs in Anilao, a famous Philippines destination for critter diving. I feel a little deflated after perusing Robert Burn’s book to find they’re probably more common at Blairgowrie Marina just down

Cover, facing page: Burnaia helichorda This page Top left: Hermaea evelinemarcusae Source & Photographer: © John Chuk Top right: Flabellina sp. 2 Source & Photographer: © John Chuk Above: Roburnella wilsoni Photographer: Planton Vafiadis © 2008

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the road; I could have saved myself the airfare! And there’s yet another trick in the adaptations of mimic nudibranchs. The entire Janolus family live and feed upon bryozoans, storing the pigments from their food in their own tissue to create an ‘invisibility cloak’ of concealment. You have to admire the ingenuity of the little buggers! If there’s one thing that comes through in this book, it is the sheer abundance of nudibranchs in southeastern Australia something not generally appreciated. Many photos are taken at local dive sites I’ve frequented for more years that I care to recall, and yet I haven’t spotted many of the common species included in this guide. Hardly surprising though when one considers the disappearing acts that some of these perform – the Melibe RB3 is virtually indistinguishable from the brown algae it lives on and the chromodorid Noumea verconis looks more like pink sponge than pink sponge does! Full credit to the dedication of photographers such as John Chuk and Leon Altoff who have

contributed so many images of these obscure and cryptic species – they must have spent thousands of hours underwater, often in harsh locations. Robert Burn’s Nudibranchs and related molluscs is the product of more than 60 years of research, experience collecting, observing and studying the creatures both in the field and under the microscope. Many of the images and much of the information has resulted from the Under the Lens and Bioscan partnerships between Museum Victoria and Parks Victoria. Robert Burns is an internationally respected authority on the marine group to which nudibranchs and related molluscs belong and has been afflicted with a love of these animals since childhood. Robert has identified more than 50 species and also has a number named in his honour including Robernella and Burnaia. This comprehensive and interesting text will be sought after by naturalists, divers and underwater photographers. Published by Museum Victoria, RRP AUD$34.95 Paperback, colour illustrations, 266 pp Email: publications@museum.vic.gov.au

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sportdiving magazine 2016 Issue 171