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Redlined Jorunna Love Triangle
Redlined Jorunna nudibranchs made a rare appearance in Gorontalo. During the required safety stop, divers hovered over a patch of sandy rubble as they rested for three minutes. Looking at the sandy bottom, they discovered a cluster of black Long-spined sea urchins, several shy pipefish, and sea stars. Then, in the gentle surge, they noticed a moving, intertwined mass. It was three Redlined Jorunna nudibranchs engaged in group mating!
Love among Redlined Jorunna
Like other nudibranchs, this species is hermaphroditic. This means each nudibranch has both male and female reproductive organs. To fertilize the eggs, sperm must come from another individual.
It seems the three Redlined Jorunna we saw were donating sperm to each other. Nearby, divers noticed a pinkish ribbon of eggs already laid. According to scientific observers, this nudibranch species only appears in the open during mating. Otherwise, they hide in the reef.
Red lines and Fur
The scientific name for this species is Jorunna rubescens because of its reddish lines and markings. Underwater, divers can use additional light to bring out the reddish color.
Like other dorid nudibranchs, Redlined Jorunna have twin rhinophores on their heads and a bushy tuft of gills at the tail. These three parts can be pulled inside the body when the creature feels threatened.
Unique to dorids, fur-like caryophyllidia cover the body of Jorunna rubescens. Tiny spine-like spicules surround these sensory tubercles. Together, they give the body of this nudibranch a velvety appearance. As a result, some observers commonly call this species the Pink Furry Nudibranch.
For additional underwater photographs of Jorunna rubescens, including close-ups of the caryophyllidia, open this link.
Life and Environment
One of the larger dorid nudibranch species, Redlined Jorunna can grow up to 15 centimeters in length. The largest of the three we saw measured about nine centimeters. Jorunna rubescens lives on the seafloor in Indo-Pacific waters, including areas of coral reef and sandy or rocky bottoms like those found we found. For your chance to see unusual marine life in Gorontalo, please make your dive reservations directly with Miguel’s Diving.