Traveling with a “Baby” Shield

Researchers used blackwater photography—a technique of taking photos in the open ocean at night—to snap pictures of filefish, driftfish, pomfrets, and a young jack swimming around with larval anemones in their mouths. Anemones are already part of a well-known mutualistic partnership with clownfish, which shelter in grown anemones, eat their leftover food scraps while keeping the anemones free of parasites, and circulate water around them. In this newly discovered relationship, the mutualism is short-term but has potentially long-term ramifications for anemone populations. Larval anemones can only travel so far on their own, but being carried further afield by fish means expanding their range.

The small fish, meanwhile, carry the anemone almost like a defensive shield; anemones pack a nasty sting that predators would likely want to avoid. The sting might not kill a fish that tries to take a bite, but it’s a far less tempting meal. The exciting discovery has now raised more questions for scientists to explore: How far and how long do the fish carry the anemone? Do they swap them out? How many anemones survive the trip? What exactly triggers fish to pick up anemones in the first place? Only further study may reveal some of these answers.