Glaucus marginatus

…a small species of pelagic aeolid nudibranch in the family Glaucidae, which also houses its more famous cousin G. atlanticus. G. marinatus is commonly seen throughout the Pacific Ocean, where like G. atlanticus it spends its time floating upside down on the ocean’s surface, feeding on colonial cnidarians such as the Portuguese Man of War. 


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Image: dapete


Hermissenda crassicornis

Sometimes known as the “opalescent sea slug”, H. crassicornis is a species of Facelinid nuibranch which inhabits coastal intertidal zones from Alaska south to Mexico. Like other nudibranch species H. crassicornis feeds mainly on sessile invertebrates, specifically hydrioids and occasionally sea anemones, tunicates, and others. 


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Images: Brocken Inaglory and Jmalin

Flabellina exoptata

…sometimes known as the Much-desired Flabellina or the Desirable Flabellina, F. exoptata is a colorful species of Flabellinid nudibranch which was first described from Madang, Papua New Guinea in 1991. It is know known to be widespread throughout the tropical waters of the Indo-West Pacific. Like other nudibranchs, Flabellina exoptata is predatory and will feed on a range of sessile invertebrates. 


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Image: Chika Watanabe

Flabellina varrucosa

…a species of aeolid nudibranch in the Flabellinidae that is found on either side of the northern part of the Atlantic Ocean. It ranges from the Gulf of St Lawrence and the Gulf of Maine, and most of the North Atlantic Ocean. Individuals from British Columbia and Alaska are sometimes identified as this species but are very likely a sibling species. F. varrucosa is a predator feeding on a range of sessile invertebrates (preferring Tubularia indivisa). But they are also known to feed on detritus and plankton.


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Image: Bernard Picton

Pteraeolidia ianthina

…a strikingly marked species of of Facelinid nudibranch which is known to occur among shallow coral reefs throughout the Western Pacific Ocean, from Hawaii to the Philippines, to the waters of northeast Australia and parts of New Zealand. It is also known from the Red Sea. P. iathina is known to feed almost exclusively on hydroids, generally those which contain Symbiodinium spp. These dinoflagellates are “farmed” in the digestive diverticula of P. iathina allowing the sugars they photosynthesize to be used. 


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Image: Richard Ling

“Minature aeolis” (Tenellia adspersa)

Also sometimes known as the “lagoon sea slug”, the miniature aeolis is a small species of Tergipedid nudibranch, which is distrusted from the Northeastern Atlantic to the Mediterranean Sea, and Caspian Sea. Miniature aeolis are known to inhabit coastal intertidal and sublittoral zones, and feed mainly on hydroid colonies. 


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Image: USGS


Phyllodesmium briareum

…is a species of Favorinine nudibranchi (Facelinidae, Favorininiae) which is widely distributed throughout the Indo-Pacific and Australia. Phyllodesmium briareum are noted to feed mainly on various corals, specifically members of the suborder Sleraxonia. P. briareum is also noted for its ingenious camouflage, its cerata (the gills along its back) have been modified to look almost exactly like the tentacles of the Sleraxonian coral Briareum violaceum (which you can seen in the second picture above) this allows P. briareum to feed among B. violaceum without being targeted for predation!


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Images: Steve Childs and Heike Wägele & Annette Klussmann-Kolb