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Recent research has shown that sea slugs exhibit remarkable behaviors to deter predators, depending on their vibrant colors and patterns. Instead of hiding away, many of these bright sea slugs are more active during daylight, utilizing sunlight to enhance their warning displays. This research is highlighted in a study published on April 15 in the Journal of Animal Ecology.
Researchers from the University of Queensland in Australia investigated the coloration of sea slugs across 45 species native to eastern Australia. The findings reveal that, similar to well-known poisonous species like some nudibranchs and dart frogs, these sea slugs have developed strikingly vivid colors. Nudibranchs, part of the sea slug category, exemplify this phenomenon with their bold hues.
A panel of dorsal images of the 45 sea slug species examined in this study. CREDIT: Cedric van den Berg
According to Cedric van den Berg, visual ecologist and co-author of the study, “Sea slugs utilize vivid and contrasting color patterns to convey messages such as ‘Don’t eat me, I’m poisonous,’ to potential predators.” This strategy of using color to signal danger is a crucial part of their survival.
Goniobranchus collingwoodi, a species found both day and night. CREDIT: Louise Forster.
The research team employed specialized cameras and advanced software to model how these sea slugs appear to predators. Focused on shared color pattern characteristics, the researchers devised a method to synthesize nearly 160 color variants into a single “fingerprint.” This allowed them to highlight differences in appearance between species that are diurnal and those that are nocturnal.
Their results indicate that brightly colored spots, thick stripes, and defined body outlines serve as signals to potential predators, indicating the presence of defensive adaptations such as stinging cells or chemicals. Enhanced visibility during daylight conditions was found to strengthen these visual cues.
Goniobranchus splendidus, a species known for its striking daytime appearance and effective chemical defenses. Credit: Cedric van den Berg
Van den Berg explained, “The use of these visual tactics aligns closely with being active in the daytime, as adequate light is essential for these signals to be effective.” This adaptation not only minimizes the risks of predation for these slugs, toxic or otherwise, but also helps teach predators to recognize and remember these distinct appearances.
Marionia sp, a nocturnal species found among soft corals, where it blends in seamlessly. CREDIT: Cedric van den Berg.
In stark contrast, the sea slugs that are primarily active at night do not typically evolve bright colors or patterns, as their nocturnal predators rely less on vision and more on tactile and olfactory cues to hunt.
The researchers anticipate that their findings will pave the way for a deeper understanding of how defensive coloration has evolved in various marine species.
Source
www.popsci.com