Zuzana Musilova and Sara Mae Stieb
When animals look out into their world, they don’t all see the same thing. For some, light is abundant, even overwhelming. For others, it is vanishingly scarce. Vision is one of the most adaptable sensory systems, and in this Special Feature we explore how it is shaped and challenged by environments at their most extreme.
Too little light
From caves to the deep ocean, some habitats offer almost no sunlight. Here, evolution takes two very different paths: eyes may shrink or disappear altogether, or they may become highly specialized to capture even the faintest photon. In the deep sea, vision persists also thanks to bioluminescence—the living light that makes communication and survival possible where the sun never reaches.
Too much light
At the other extreme, animals in deserts, snowy landscapes, or the polar summer face relentless brightness, glare, and harmful UV radiation. To survive, they rely on a mix of filters, pigments, and clever behaviour, such as shifting activity into the night. Polar animals like reindeer provide a striking example of how species must navigate both dazzling summers and nearly lightless winters.
Changing environments
Vision is also under pressure from environments that change rapidly—sometimes too fast for evolution to keep up. Human activity has added new challenges: artificial lights, murky waters, or degraded habitats. These can disrupt orientation, communication, and even the boundaries between species. Coral reef fishes, for example, show remarkable but variable flexibility in their vision, revealing both the potential and limits of plasticity.
Why vision matters
Taken together, the articles in this Special Feature show how evolution has stretched the possibilities of the vertebrate eye to its limits. Whether in total darkness, blinding light, or rapidly shifting conditions, vision continues to surprise us with its resilience—and its fragility. Understanding these adaptations offers not just a window into evolution’s creativity, but also a glimpse of how animals might cope with today’s accelerating environmental change.
Behind the process
The idea for this Special Feature grew out of the Intecol 2022 conference, where we hosted a symposium on sensory systems in challenging environments. The energy of that meeting sparked the thought that a collection on this theme could really bring the field together. Many of our contributors were participants in the symposium, while others were invited afterward to ensure we covered a broad spectrum of organisms and research questions.
Editing the issue often felt like assembling a puzzle—watching the pieces fall into place as each paper arrived was deeply rewarding. We overcame all challenges, such as finding suitable and available reviewers, and we enjoyed the ride. Our advice to future guest editors: cast a wide net for contributors—you’ll end up with a stronger and more exciting collection. In our case, many excellent research groups would have fit perfectly, but we simply didn’t manage to reach them in time.
About the authors
Zuza has always been fascinated by fish evolution, while Sara began her exciting vision research with ants. Eventually, we found ourselves in the same lab—exploring vision in fishes and trying to unravel the visual ecology of different groups. Outside the lab, Zuza looks after her aquarium and her daughter, while Sara can be found kitesurfing with her dog waiting on the shore. We both share a love for the outdoors, whether snorkeling and diving or hiking with our families—Zuza preferring flat islands, Sara the mountains:-). Today, Zuza teaches ichthyology and leads a research group in Prague focused on deep-sea fish vision, while Sara works on applied research to fish management. Balancing family and professional life can be a challenge, but with creativity and persistence, there are always solutions.
Zuzana Musilova (she/her)
- Bluesky: @fishevo.bsky.social
Sara Mae Stieb (she/her)
(Credit: Petr Jan Juračka)
(Credit: Nadia Schärli)
