An epiphany after observing a specimen of a Giant Anteater at the DMNS

 

Photo of Giant Anteater (Myrmecophaga tridactyla), Copenhagen Zoo, by Malene Thyssen.


I was looking at the Denver Museum of Nature and Science's anteater exhibit, when I got an epiphany. And it relates to... reef fish.

As a diver, I am mesmerized by the sheer variety of fish colors and patterns on a reef. I hear marine biologists talk about reef fish eyespots or ocelli, a "phylogenetically widespread, conspicuous marking that has been shown to effectively reduce predation, often through its resemblance to the eye" (see Hemingson et al 2021).

A Princess Damsel, Pomacentrus vaiuli, at North Murion Island, Ningaloo Marine Park, Western Australia. Note the obvious eyespot located above the caudal peduncle. Andrew Photo by J. Green / Reef life Survey.

Although eyespots in reef fish are hypothesized to have a number of functions, the general consensus is that eyespots found behind the dorsal fin "align more strongly with the deflective function; where eyespots divert attacks to less-important body locations allowing the individual to escape relatively unscathed." 

When diving, I find myself squinting at fish, to "see" the most pronounced characteristics. What DOES a predatory fish see through 5 meters of water? Often, the eyespot is THE most obvious coloration pattern.

Well, reef fish are far removed from giant anteaters, right? But these anteaters have a striking pattern featured on their lateral surface, especially those front legs, described as "...a black wedge that extends from their chest and neck to top of the tail flanked by a thin white line above." 

Taxidermy mounts of giant anteaters in a diorama at the Denver Museum of Nature and Science.

A striking pattern indeed. But why? So... I squinted.

Ecologist Tim Caro suggested the answer may be aposematism, a signal that marks a warning to potential predators. "Attack me and suffer the consequences." Striped skunks (Mephitis mephitis) are classic examples.

Caro postulated that anteaters "...have formidable foreclaws used to open termitaria and slash at attackers. Interestingly, giant anteaters have black and white bracelets of fur... that may draw attention to their weaponry."

A striped skunk in an alert position.

Giant anteater claws, from an article detailing the death of a hunter attempting to capture an anteater.

However, I would think that predators (their predators are large cats, jaguars and pumas), would be focused on the front claws of a slow moving mammal. Speculation, of course.

Look again at this photo, and that of the giant panda below:

Note the similarity of the anteater's front leg coloration to the giant panda.

Now, there's no reason for a jaguar to be afraid of a giant panda! Indeed, they've never interacted outside of a zoo. But what I noticed was the animal-like imagery of that coloration pattern, more like a coati. So, if you squint, or if you have your head down and are trying to sneak up on a giant anteater, at night, perhaps that jaguar would focus on... the "animal" that is actually a front leg. The jaguar attacks from the rear, and goes for a killing bite to the neck. But... it hits a leg instead, perhaps giving the anteater time to use those powerful claws for defense.

In the southern Pantanal of Brazil, jaguars preferentially preyed on cattle, caiman (Caiman crocodilus yacare), and peccaries (Tayassu pecari). Giant anteaters seemed to be killed in proportion to their abundance, as opposed to jaguars hunting for them specifically. 

This coloration defense, focusing on more of an "eyespot" deflection than aposematism, certainly doesn't work for all anteaters. But it may work well enough that natural selection has favored the persistence of this color pattern.

And that's my epiphany!

•••

Note: as I was putting the final touches on this blog, I came across a short 2023 article in the journal Frontiers in Ecology and the Environment. And I mean short... one paragraph and one photo:

But there it is, "Identity theft: anti-predator mimicry by the giant anteater?"

Authors Robert Pitman and Carl Safina independently came to the same conclusion that I did: "By projecting the likeness of a smaller prey species, an anteater might lure an attacker to a less vulnerable part of its body, which could then allow it to respond with its formidable claws."

Pitman and Safina conclude their article with the question, "Or are we just seeing things?"

I don't think they are seeing things. I just wonder how it took so long for us to see it!

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