It’s important to check out the neighbors before you move into a new place — are they loud, are they tidy, and, especially, is there an odor of death wafting around their digs?
The answer to that last question seems to play a role in where young damselfish settle on a coral reef: The odor of a predator keeps them away.
Young damselfish use smell to help determine where they settle on the reef. Credit: National Oceanic and Atmospheric Administration.Damselfish hatch near the surface, and spend their first few days drifting or swimming with the currents. After that, they pick out a nearby reef as a permanent home.
The fish aren’t yet fully developed, though, so it’s hard for them to avoid predators. In fact, more than half of the new settlers get eaten within the first 48 hours. So they need every advantage they can get.
A recent study says one advantage comes from sniffing around before they settle. Researchers placed containers holding damselfish predators at several sites around an experimental reef. The containers were screened to allow water to flow through, but keep the predators locked away. The experiment replicated life on a real reef, where predators are likely to inhabit just a few spots. The researchers then released young damselfish on the reef to see where they’d settle.
The youngsters were much less likely to settle in the areas near the predators. Since the fish couldn’t see the predators, the researchers concluded that they must have smelled them. Damselfish have a well-developed sense of smell, so it’s likely that they sniff around before they pick out a spot — keeping them safe from really bad neighbors.
