{"id":30416,"date":"2020-07-25T12:05:32","date_gmt":"2020-07-25T10:05:32","guid":{"rendered":"https:\/\/opistobranquis.info\/?p=30416"},"modified":"2020-07-25T12:05:32","modified_gmt":"2020-07-25T10:05:32","slug":"no-tots-els-nudibranquis-son-carnivors","status":"publish","type":"post","link":"https:\/\/opistobranquis.info\/en\/no-tots-els-nudibranquis-son-carnivors\/","title":{"rendered":"Not all nudibranchs are carnivores"},"content":{"rendered":"

In July 2020, an interesting article (Camps-Castell\u00e0 et al., 2020) was published in the prestigious journal Marine Ecology Progress Series (MEPS), which, under an apparently trivial title, announces a paradigm shift: \u201cNot all nudibranchs are carnivores<\/strong>“.<\/p>\n

Nudibranchs (Mollusca, Nudibranchia) have traditionally been considered one of the most highly specialized groups of predators (Megina & Cervera 2003) and, in fact, they are classified into four groups based on their diet: sponge eaters, bryozoan eaters, hydrarian eaters, and another \u201cmiscellaneous\u201d group whose diet includes other animals such as tunicates and even other nudibranchs or their egg spawns. Thus, nudibranchs, as a group, were considered carnivores (Clark, 1975; Wagner et al. 2009).<\/p>\n

The article we are commenting here studies the case of a tiny nudibranch called Polycerella emertoni<\/em> that was found in waters of the Ebro Delta (Tarragona, Spain) associated with the bryozoan Amathia verticillata<\/em> (Camps & Prado, 2018) on which it was supposed to feed.<\/p>\n

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The nudibranch Polycerella emertoni<\/em>. Picture by Manuel Ballesteros<\/p><\/div>\n

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The bryozoan Amathia verticillata<\/em>. Picture by Miquel Pontes<\/p><\/div>\n

It may seem very easy to determine what a nudibranch feeds on, but it is not, especially when the animal measures 3-4 mm and lives perfectly camouflaged on the substrate. We know that many nudibranchs that live on sponges feed on them, that many of those that live on hydrarians feed on them, that many of those that live on bryozoans feed on them, and that many of those that live on sand feed on a multitude of organisms that live in this environment. So why would one more nudibranch living on a bryozoan not feed on it?<\/p>\n

The discovery<\/h4>\n

The first suspicions appeared after an small video recorded with a microscope in which the nudibranch was feeding. It apparently nibbled on the bryozoan, but the tissue of the bryozoan appeared unscathed. But, if the supposed food was not nibbled, could it be because the nudibranch was not actually feeding on it but rather feeding on something that is not seen? What could it be?<\/p>\n

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