Crab Nation

Crab and Flower (ca. 1890-1900) by Suzuki Nanrei.

Source: Artelino

A scattering of fossilized 90-million-year-old crabs shows how an animal might turn from bottom feeder to dragonfly-like predator. Callichimaera perplexa, first identified from fossils in Colombia in 2019, lived in the warm oceans of the mid-Cretaceous. And they had truly enormous eyes: An entire adult crab was about the size of a quarter, and the eyes set in its head took up about 16 percent of that. A human with a proportionate anatomy would have dinner plate-sized peepers.

Seven of the crabs are so well preserved that in a recent paper published in the journal iScience, a team of paleontologists could examine the facets of their compound eyes, and even the shape of the nerves between eyes and brains. That tissue suggested that the C. perplexa, or chimaera crab, saw almost as sharply as a dragonfly, and more sharply than a mantis shrimp, which hunts snails and crabs.

The paper: https://www.sciencedirect.com/science/article/pii/S2589004221015492

Truly awesome news for crab lovers this week!

I remember when this baby was first discovered and it sure gained a lot of attention with its bizarre look.

As for those of you that came for the crab meme, be not disappointed:

“There’s sort of a debate over what makes a crab,” says Jenkins. The word is used to describe both an evolutionary group, like “mammals,” and unrelated organisms that share a basic shape, like “trees.” “[C. perplexa] is a true crab in the sense that it belongs to this group that evolved during a certain time. It gives us insight into what it means to be a crab.”

Luque points out that although many animals have stumbled upon the “crab” body shape, there are even more examples of crabs evolving into another shape—as C. perplexa demonstrates. It could be that crabbiness is also a platform for adapting to new ecosystems. “You don’t see lobsters climbing trees, and you don’t see shrimp living on beaches,” Luque says. “Crabs have done that all, and more.”

Crab says:

The crab.