DIVE LOG Australasia

JUVENILE JURY N owhere is it more important to apply the golden rule: “ Look for what is the same rather than what is different ”, than when examining what maybe a juvenile of a species. Often small and with ill-defined features a juvenile frequently presents a conundrum to the finder. They grow and develop from a shapeless form that we are unable to see in their early most stages. A degree of imagination usually needs to be applied. There are of course many species of tiny sea slugs too, making it all the more difficult. Collecting a portfolio of different stages of maturity is helpful. It’s always tempting to think you have found a new species to add to your list. If it is a juvenile, console yourself with the fact that they are not often observed and to have a record of a different life stage is quite remarkable in itself. From small things - big things grow. Here are just a few. Is It Different? - Is It New? - Maybe It’s A Juvenile

Above : Recent molecular testing has revealed that Hexabranchus is not a monotypic genus and that even the species now identified and separated also have morphotypes (different appearance). Additionally the juveniles, being vastly different to the adult, undergo a raft of changes in reaching maturity. Left : A juvenile and adult of Hexabranchus lacer . Right : A juvenile and adult of Hexabranchus sanguineus .

Above : The dorid Dendrodoris denisoni . Left : the juvenile form has most of the features of the adult but just in a different and more basic form. Right : The adult has more tubercles some of which are compound, additional blue spotting that is more vibrant, a reticulation of thin white lines on the notum and rhinophores with a distinct club. The mantle border though is recognisable having undergone little change.

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DIVE LOG Australasia #408 - October ‘24

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