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Dead nudibranch is rarely seen. But one of our sharp-eyed dive masters spotted one along an unnamed section of coral reef.
A Black, Fleshy Mass
Miguel’s Diving staff are always looking for marine life to show to our diving guests. They are skilled in spotting small critters, as well as pelagics that swim past divers who are focused on the amazing coral here.
Recently, a dive master noticed something out of place in a small patch of white sand. The object looked black and fleshy, like the mantle of a clam. However, he knew that no clam lived there in the sand.
With a piece of broken coral, he probed the strange thing. It was clearly dead and lifeless. Upon closer inspection, it was clearly the dead body of a large nudibranch. Round holes remained where the rhinophores had been during life. Towards the back, the area where the gills should have been were completely torn. We have placed circles around the missing dorsal parts in the photograph.
Turning the dead nudibranch over on its back, he saw that the entire area of internal organs was entirely ravished. Only the fleshy body of the dead nudibranch remained.
An Expert Comments on the Dead Nudibranch
Everyone at Miguel’s Diving was curious to learn about this unusual sighting. None of us had ever seen a dead nudibranch before. We wanted to learn how this marine critter could have died. So, we contacted an expert. She is Prof. Dr. Heike Wägele of the Leibniz Institut zur Analyse des Biodiversitätswandels Zoologisches Forschungsmuseum. She kindly responded to our email.
She speculated that the nudibranch could have experienced an injury to its back. As a result, fish began to nibble at it. Another alternative could be damage from a parasite. “Copepods usually sit close to the gill and perhaps this has also weakened the animal,” wrote Dr. Wägele. Sometimes, the nudibranch ages and dies naturally.
We also asked her why only parts of the dead nudibranch were eaten and not its body. She responded, “Usually these animals have toxic compounds accumulated in the body, mainly actually in the large body. But the organs are usually less toxic.” Also, the bodies of nudibranchs are full of spicules. Spicules are hard and spiny. They help support the body structure of marine animals that lack bones. Also, they make their bodies unpleasant to chew.
Given the extreme decay of the specimen, there is no way to know what species of nudibranch we found dead. However, its shape and size are similar to Ardeadoris egretta. Divers occasionally see this beautiful white nudibranch along coral reefs in Gorontalo.
For your chance to see a living nudibranch, please make your dive reservations directly with Miguel’s Diving.