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Day 301#: Eyespot Bowfin

Today's animal of the day is the Eyespot Bowfin (Amia ocellicauda)!

Photo credit: Below Blue Water Diver

Also known as the emerald bowfin, this species of freshwater fish can be found throughout North America, from Ontario, Canada, all the way down to the Gulf Coast. They prefer to inhabit slow-moving bodies of water with soft substrate, such as sand or mud, and lots of aquatic vegetation. These fish can reach lengths of around 36.5 inches and have long, cylindrical bodies. As their name suggests, they have black and yellow eyespots near the start of their caudal fin. Sometimes females can be born without these spots, though this usually isn't a sure-fire way of differentiating the sexes.

Photo credit: Lindsey Smith

They are nocturnal predators that hide in deeper waters during the day and come out at night to feed. Their sharp teeth and powerful jaws help them to latch onto slippery prey, such as shads, sunfish, crayfish, worms, frogs, bullheads, and many other aquatic animals. Their coloration also helps them sneak up on prey, since their dark olive green top halves help blend in with the lake bottom if you're looking down at them from above, and their cream underbellies blend in with the bright surface if you're looking up at them from below. This is called countershading and is a common camouflaging tactic used by many aquatic and marine predators.

Photo credit: Kristen Osborne

During the spawning season, which takes place from May to June, the fins and bellies of the males will turn a bright green color, and they will build a little nest out of a patch of water plants to attract a mate. If a female decides that she likes a male's nest, she will lay around 64,000 eggs inside of it for him to fertilize and will then swim off to mate with another male. Males will stay behind and guard their eggs until they hatch. Once the fry hatch, they will feed on various types of tiny crustaceans and aquatic insects until they're big enough to go after larger prey. In the wild, males have been documented having an average lifespan of 6 years, while females tend to live between 10 and 12 years. However, some female specimens from Minnesota were recorded living up to 33 years!

Photo credit: Jackson Nesbit

Eyespot bowfins were originally considered to be just a regional variant of the ruddy bowfin. However, genetic analysis done in 2022 revealed that the two were actually totally different species that split off from each other between 1 and 2.5 million years ago during the mid-Pliocene epoch. There are a couple of other morphological differences between these species as well, such as the eyespot bowfins having a more pronounced eyespot, having only 15 fentary teeth instead of 16 or 17, having a less red hue, and being slightly longer. However, the two species still look incredibly similar, which has caused scientists to suspect that there might be more bowfin species out there that are hiding in plain sight.