Why these sea slugs look so much like David Bowie

Though it has been three years since David Bowie died, his legacy continues to inspire fashionistas.

The rock star was known for wearing vibrant colors and imaginative textures, looks mimicked by scores of trend setters. But perhaps no other creatures bear a more striking likeness to Bowie than sea slugs.

Hear me out.

This is an argument that inspired the entire creation of Bowiebranchia, a blog that’s been active since 2015 with the sole purpose of comparing the iconic styles and moods of the late rock star with these soft-bodied, underwater invertebrates.

Nudibranchs, sacoglossans and other sea slugs carry showy exteriors on purpose. These creatures burst with colors to warn predators that their slimy innards may be toxic or distasteful. By drawing comparisons between sea slugs and the man who created Ziggy Stardust, Bowiebranchia exposes what we can learn about the wild, beautiful and competitive evolution of both.

“They’re both trying to stand out,” said evolutionary biologist Anne Winters. “He’s trying to make a statement and get recognized for his individuality and his music, and nudibranchs are trying to get recognized too.”

Oh! You Pretty Things

Tracy Dendy, a New York-based designer, is the brain behind Bowiebranchia, who said that she originally started using images of sea slugs as placeholders when designing new projects.

When a co-worker pointed out the resemblance between a particularly vibrant photo and one of Bowie’s more fantastic outfits, she realized the potential for a blog.

“I had never really known that much about David Bowie, but I was really into sea slugs,” Dendy told the PBS NewsHour. More than three years in, the page has more than 8,000 followers on Tumblr.

For Dendy, the draw of the blog was strictly the visual oddity and eerie perfection of the comparisons she could make.

Online, she makes the comparisons in a simple side-by-side format. Matching lighting, matching colors and matching moods evoke the musician’s many changes, as well as the wild twists and turns of natural selection.

After years of collecting photographs of sea slugs and The Thin White Duke (one of Bowie’s many memorable personas), Dendy has learned to appreciate sea slug cladistics — the categorization of living things. It’s a habit usually reserved for evolutionary biologists.

“Lots of times now, if I find a sea slug that’s similar enough, I’ll find its family or genus and search through that to find the perfect picture,” Dendy said. “I totally have all the names memorized. I’ll be like, ‘Yeah, I want a Hypselodoris right now.’”

The science behind sea slugs’ colorful patterns

It’s no accident that the sea slugs’ colors and patterns are so bold. The slugs were “under pressure” to find a way to live without the shells that protect their relatives (snails) — they needed protection from being eaten.

To ward off attackers, Winters said, the slugs evolved to innately produce foul chemicals or to steal the toxins by eating poisonous creatures like sponges and cnidarians. But a predator considering whether it should take a bite wouldn’t know about those chemicals until it was too late for the slug.

Their toxins would be more successful if the slugs could signal that both predator and prey would suffer from an attack. Hence, the bright yellow rings or contrasting patches, the lime-green fluorescence or the appearance of wicked spikes on the most flamboyant sea slugs.

This type of advertisement is known in biology as aposematism. It’s a billboard that says “Hey! Watch yourself or you’ll regret this.”

But not every slug wants to expend the effort to be as toxic as their outsides might claim, Winters said. Some sea slugs cheat by mimicking their more dangerous relatives without actually producing hazardous chemicals. These slugs rely on the fact that undiscerning predators will assume that they, too, are not to be bothered.

Harmless king snakes that imitate the stripes of deadly coral snakes use this kind of mimicry, as do stingless flies that look like aggressive yellow-and-black wasps.

Fashion oddity?

What would Bowie have thought of this comparison? “I’m fairly certain he would have loved it, actually,” said Paul Trynka, a rock ’n’ roll journalist and Bowie biographer.

Trynka said Bowie’s increasingly eye-catching and extreme outfits were driven by natural selection, much like for nudibranchs.

“The era we’re discussing — the glam era — was a very, very competitive one. Bowie had to be successful. He was kind of Darwinian in that sense,” Trynka said. “Survival of the fittest is a fairly brutal concept. In the same way, Bowie could be very brutal and competitive.”

In that way, the blog is “a good sort of memorial to Bowie’s otherworldly nature,” Trynka said. “Deep down in the sea is one of our last undiscovered frontiers, and he … he was the Starman.”