From neon-blue polka dots to flame-like tails, 17 newly described sea slugs are adding to what we know about how color evolution works in the animal kingdom – and looking absolutely fabulous while doing so. In addition to describing the new slugs, researchers identified how their distant relatives evolved similar color patterns in the first-ever genetic confirmation of color mimicry across the sea slug world.
Using a combination of visual analysis and genetic testing, scientists with the California Academy of Sciences added 17 new species of the nudibranchs to the tree of life. They also defined the role color mimicry plays in the marine invertebrates’ defense against predators by creating “color trees” to see how the slugs evolved their flashy wardrobes. Further genetic analysis showed that several species from distantly related groups evolved similar color patterns in a process known as “convergent evolution”, whereby species take on similar traits because of environmental advantages or ecological niches. It's likely this happened with different-colored sea slugs that mated in order to take on another’s advantageous color traits. Their work is published in the Zoological Journal of the Linnean Society.
“Usually, most nudibranchs have distinctive color patterns that allow us to recognize distinct species. These are indicators of warning coloration in these distasteful species. Some nudibranchs do mimic each other and have similar (but subtly different) color patterns, ensuring that predators have to recognize fewer color patterns for distasteful species,” study author Terry Gosliner told IFLScience. As he notes, sea slugs have an “arsenal of strategies for surviving,” from their mimicry to camouflage to cryptic patterns. These color variations are influenced by a strong selection pressure to have similar color patterns.