#threadfin butterflyfish
Brought to you by a marine biologist and fish with 4 eyes…or is it???
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We’re staying on the coral reef to explore more colorful camo. I know, it sounds weird, but last time we spoke about the Flame Angelfish, we discussed why coral reef fish are so colorful. It actually works in this clear, yet complicated environment where natural selection and sexual selection agree to create attractive colors that also help them hide. Today we’ll cover another denizen of the Indo-Pacific tropics to talk about one of the more popular methods of confusing predators - the eye spot. The fish that sports this today? The Threadfin Butterflyfish!
This one *just* appeared in AC Pocket Camp last month (March 2022) for the 48th fishing tourney. We may never see it again! Only time and Nintendo will tell!
Anyway. The threadfin is named to species - Chaetodon auriga, of the family Chaetodontidae, the butterflyfishes. Now, this group may look a lot like the marine angelfish - both groups sport some incredible colors and they are laterally compressed, which means they are really narrow when viewed from any angle by their left and right sides, which make them appear wider. This shapes is common in fish, but both these traits together make it really hard to separate which fish are butterflyfish and which are angelfish. The primary difference is that marine angels have a sharp spine on their operculum, the gill cover, while butterflies don’t. It’s such a tiny feature, but that’s the distinction. The threadfin itself distinguishes itself from other yellow-and-white fish with the long filament coming off its dorsal fin. AC did such a great, detailed work on that icon, dang!
By Bernard E. Picton BernardP - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=3280848
One thing you’ll notice about some reef fish are a single black spot on the opposite end of their bodies, while their eyes are covered by a dark stripe. This is a common method to deceive predators into thinking the fish’s head is on the side with the false eye, or eye spot. True, no one wants a chunk taken out of them, but if you had to choose, I’m sure you’d choose dorsal fin over your face. This may also confuse even a smarter predator that thinks ahead - if it thinks the fish’s face is on that side of the body, it makes logical sense that it would move forward that way. In that instant, the butterflyfish can dart in the opposite direction and get out of dodge.
It’s an incredible play on mimicry and camouflage, but not every threadfin butterfly has the eyespot. Some taxonomists would say they aresubspecies of each other, and therefore they are named as such. The one without the eyespot - Chaetodon auriga auriga - is native to the Red Sea, while the one with the eyespot - Chaetodon auriga setifer - is native to the rest of the threadfin’s range, which is huge. It’s very widely distributed across the Indo-Pacific, from outside the Red Sea to Hawaii, north to Japan, and South to French Polynesia.
And there you have it. Fascinating stuff, no?
