Animals Wildlife 12 Favorite Sea Slugs of the Man Who’s Discovered More Than 1000 of Them By Melissa Breyer Editorial Director Hunter College F.I.T., State University of New York Cornell University Melissa Breyer is Treehugger’s editorial director. She is a sustainability expert and author whose work has been published by the New York Times and National Geographic, among others. our editorial process Melissa Breyer Updated October 11, 2018 ©. Cuthona sp. (Terry Gosliner/California Academy of Sciences) Share Twitter Pinterest Email Animals Wildlife Pets Animal Rights Endangered Species Terry Gosliner’s lifelong passion for nudibranchs has taken him all over the world in search of the surreal sea slugs; here are his greatest hits. Everybody has their thing – the world would be a dull place without people with passion. For Terry Gosliner, fervor comes in the form of a far-out-looking soft-bodied marine mollusk known as a nudibranch, also familiarly called a sea slug. And is it any wonder? If there were ever a candy-colored sea creature more Dr.-Seuss-meets-Studio-Ghibli than a nudibranch, then I challenge you to show it to me. Beloved for their neon hues and completely wacko assortment of shapes and frippery, they’ve evolved a whole host of curious defense mechanisms to compensate for their lack of a protective shell. In that regard, they are kind of like the caterpillars of the sea, as you can see here in this collection of images that Gosliner calls his "greatest hits album." © Hypselodoris sp. (Terry Gosliner/California Academy of Sciences) © Chromodoris joshi (Terry Gosliner/California Academy of Sciences) As explained by the California Academy of Sciences, where Gosliner serves as Curator of Invertebrate Zoology and Geology, it’s not just their looks that earn the nifty creatures accolades: Some nudibranchs have admirable camouflage skills; others go the opposite way, exhibiting shockingly bright colors and patterns meant to warn predators away. Perhaps their most impressive defense, however, is an arsenal of chemical weapons, many shaped by diet. Nudibranchs that feed on certain sponges, for example, become toxic to predators when they concentrate the sponges’ toxins in their own bodies. Nudibranchs adapted to feed on hydrozoans—like the Portuguese man o’ war—can safely ingest and store their dinner’s stinging cells, eventually moving those cells to the outsides of their own bodies and becoming stingers in their own right. “This [range of defenses] is what makes the nudibranchs so diversified,” says Gosliner. “It results in their freedom of movement, diversity of form, and the intensely bright coloration they use to advertise against predators. Everything about them just piques the imagination.” © Miamira alleni (Terry Gosliner/California Academy of Sciences) © Siphopteron nakakatuwa (Terry Gosliner/California Academy of Sciences) © Halgerda sp. mesophotic (Terry Gosliner/California Academy of Sciences) Gosliner grew up in California, sleuthing the tide pools; his sea slug fate was determined as a teen upon being introduced to his first live nudibranch. “I was hooked,” he says. “That’s when I really started looking into California nudibranch species. I wanted to find every single one of them.” He discovered his first species in high school, and hasn’t stopped since. He estimates that he’s discovered between 1,200 and 1,500 new species of nudibranchs – about one-third of all sea slug species that are known to exist. He's published more than 150 scientific papers on the little guys, in addition to having written five books. © Melibe colemani (Terry Gosliner/California Academy of Sciences) © Chelidonura alexisi (Terry Gosliner/California Academy of Sciences) © Carminodoris estrelyado (Terry Gosliner/California Academy of Sciences) Now, in addition to combing the ocean depths in search of more of these beauties, he also spends time with both students and government officials, hoping to increase awareness on issues of ocean sustainability and advocating for protection of biodiversity hotspots. © Hypselodoris sp. (Terry Gosliner/California Academy of Sciences) © Blue-spotted Dermatobranchus caeruleomaculatus (Terry Gosliner/California Academy of Sciences) © Janolus sp. (Terry Gosliner/California Academy of Sciences) “You can’t just accept discovering science as ‘enough,’” Gosliner says. “We have an obligation to explain its relevance. We need to find more ways to transfer scientific findings to the public so that we can positively impact public policy and conservation management – especially now, when the natural world is changing so rapidly.” Saving the world, one soft-bodied psychedelic sea slug at a time.