If a Fish Could Build Its Own Home, What Would It Look Like?

By exposing fish to experimental constructions, scientists hope to find out if replicating coral reefs is really the way to go

Damselfish typically live in the nooks and crannies of coral reefs. But do you have anything with more of an open concept? (Humberto Ramirez/Getty Images)
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As climate change and human depredations destroy ecosystems across the globe, scientists are stepping in to offer beleaguered animals temporary housing. For an octopus in the Mediterranean Sea, that artificial refuge comes as a sunken plastic pipe, while in the Hyères archipelago off France, nesting seabirds can cozy up in semiburied plastic jugs. But some scientists are going further and designing housing from scratch.

At the University of Delaware, for example, ecologist Danielle Dixson has shown that 3-D-printed replicas of natural coral, crafted from a biodegradable cornstarch substrate, can provide temporary scaffolding for a recovering coral reef. Dixson and her colleagues analyzed the necessary structure for reef fish housing—a coral with too many branches prevents fish from fitting inside, but wide gaps allow predators to sneak in and wreak havoc—and concluded that nature had already gotten it right.

Other researchers are stretching their imaginations even more. If these replacement homes are artificial anyway, then why simply replicate an existing habitat? Are the dwellings animals find in nature really what they want? If, given the chance, a fish could design and build its own home, what would it look like? And if scientists could somehow figure out a fish’s ideal habitation, could they make that instead?

Alex Jordan, an evolutionary biologist at the Max Planck Institute of Animal Behavior in Germany, is searching for the answers to those questions. Jordan and his colleagues are embarking on research about the housing preferences of damselfish—species that are crucial to the healthy functioning of coral reefs—by presenting them with a panoply of options and tracking their behavior to figure out which features they value most.

“What structural elements do animals want and what do they need? Can we give them those things?” Jordan says. “We’re asking fish to become architects of their own spaces so we can understand what they want in their own world.”

Jordan’s efforts have already shown that some marine animals prefer artificial structures over natural ones. After 3-D printing a variety of shells and observing which ones cichlids gravitate toward, the scientists discovered that the fish opt for huge shells—ones that would never occur in nature. The finding shouldn’t be that shocking. After all, few among us would choose a cave over a castle.

Jordan’s research represents a confluence of art and science, and some of his team’s test structures—including a ceramic brick that looks like a Rice Krispies Treat; a metal sponge that’s been injected with gas that forms gaping holes, creating a trypophobe’s nightmare; a Barbie-pink block engineered for maximum surface area; and a simple three-dimensional hexagon—were designed at the studio of Rasmus Nielsen, a Danish artist and member of Superflex, a group that engages with environmental, social, and political issues through art. Jordan calls the designs “fish Legos,” while Nielsen calls them “Ikea for fish.”

Covid-19 has thrown a wrench into Jordan’s timeline, but once the pandemic subsides, he intends to replicate the cichlid laboratory research in the wild. He’ll also test out those fish Lego bricks by installing them on reefs in the Red Sea and taking note of which structures damselfish prefer, allowing them to become their own Frank Gehrys or Frank Lloyd Wrights.

Jordan believes that his team will be able to create a structure that fish prefer over natural coral. “But I have no real notion yet about what the change will be,” he says.

Aside from trying to understand damselfish design sensibilities, Jordan and Nielsen are hoping to make a statement about animal consciousness by demonstrating that fish hold preferences about their habitat.

There’s another application to this research, both existential and practical, Nielsen says: “The far goal would be to translate this in my lifetime to human architecture.”

With sea level rise, many of the buildings we’re constructing along our coasts will be submerged within a century or so. Perhaps architects might design new coastal dwellings that take human desires into account, but also look to the future—creating constructions meant to be given over to the sea and incorporating elements for the creatures that will inherit them. Making a castle fit for a human, but also for a damselfish.

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

Related stories from Hakai Magazine:

Plastics Are Messing with Fish Physiology

Giving Coral Reefs a Second Chance with Probiotics

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