How Clownfish Use Math to Survive and Thrive

Analysis reveals that frequent clownfish can distinguish between their very own species and different species by counting the variety of white bands on the edges of fish. This functionality permits them to aggressively defend their anemone houses from intruders of their very own species whereas displaying tolerance in direction of different species. Credit score: SciTechDaily.com

Clownfish rely stripes to tell apart good friend from foe.

Nemo, the small animated fish, is an icon, snuggled up along with his father in an anemone. And Pixar would have you ever imagine that anemonefish life is usually peaceable and tranquil. However the fantasy belies actuality.

Anemonefish (also referred to as clownfish) are feisty little creatures, enthusiastically defending their anemone houses from intruders. And whereas it’s generally positive to share with anemonefish of different species, it’s by no means cool to cohabit with intruders of their very own species: they at all times obtain the frostiest reception.

So how do anemonefish inform members of their very own species other than different stripy fish?

Based on Kina Hayashi from the Okinawa Institute of Science and Know-how, Japan, anemonefish species that reside in the identical areas are likely to have a variety of stripy patterns – from three vertical white bars to none.

Would possibly anemonefish be capable to rely the variety of white bands on different fish’s our bodies to tell apart good friend from foe? Kina Hayashi and colleagues revealed the superb discovery that frequent clownfish (Amphiprion ocellaris) can rely in Journal of Experimental Biology.

Experimentation and Findings

To seek out out, Hayashi, Noah Locke and Vincent Laudet raised a faculty of younger Nemos, frequent clownfish, from eggs, to make sure that the fish had by no means set eyes on different species of anemonefish.

As soon as the kids have been ~6 months outdated, Hayashi filmed their reactions to different anemonefish species – together with Clarke’s anemonefish (A. clarkii), orange skunk clownfish (A. sandaracinos) and saddleback clownfish (A. polymnus) – in addition to intruders of their very own species, to learn how they responded.

Certain sufficient, the frequent clownfish gave members of their very own species, with three white bands, the toughest time, dealing with off towards 80% of the fish for as much as 3 s and even sustaining an 11 s standoff with one fish. In distinction, the intruders of different species had a neater time: the orange skunk clownfish – with no aspect bars and a white line alongside its again – obtained off the lightest and have been barely confronted, whereas the Clarke’s clown fish and saddleback clownfish – with two and three white bars, respectively – have been mildly bullied.

“Frequent clownfish… attacked their very own species most often,” says Hayashi.

However how have been the clownfish distinguishing between members of their very own species and others?

This time, the group remoted small shoals (three fish) of younger frequent clownfish in particular person tanks after which filmed the fish’s reactions to both a plain orange fish mannequin or fashions painted with one, two or three white bands, retaining a tally of how typically the fish bit and chased the offending intruder.

Certain sufficient, the younger clownfish paid little consideration to the plain orange mannequin, just like the shortage of curiosity that they had proven within the orange skunk clownfish, whereas they nipped and pursued the mannequin with a single bar every now and then.

Nevertheless, they actually turned up the strain on the three-striped fashions; they didn’t like sharing area with the three-barred strangers that appear like themselves. And the two-striped fashions additionally got here in for a bullying.

Hayashi means that the clownfish’s aversion to fish with two bars might relate to their growth. Frequent clownfish initially kind two white stripes at ~11 days of age earlier than gaining the third 3 days later. She suspects that clownfish that develop up with different two-striped kids might see fish with two white bars as opponents to be chased away.

Implications of Clownfish Conduct

So, younger frequent clownfish that make their houses in anemones can distinguish species that pose a risk from these that don’t based mostly on the variety of white bars on the fish’s sides. This enables them to defend their abode from intruders which may attempt to evict them, whereas paying much less consideration to fish of different species which have little curiosity in organising residence of their anemone residence.

Reference: “Counting Nemo: anemonefish Amphiprion ocellaris establish species by variety of white bars” by Kina Hayashi, Noah J. M. Locke and Vincent Laudet, 1 February 2024, Journal of Experimental Biology.
DOI: 10.1242/jeb.246357