Millions of years ago, the ocean was full of weird creatures. Some looked like crabs, but genetically, they weren’t actually crabs. Scientists have been wondering why so many animals evolved to look like crabs. It turns out, the crab shape is very advantageous. Let’s find out why.
The Fossil Crab
About 10 million years ago, a spiky, clawed creature roamed the ocean off the coast of what is now called New Zealand. This spiky animal is called Paralomis debodeorum, and as much as it looked like a crab, it wasn’t. Only one fossil of its kind was ever found, making it a mystery to scientists.
False Crabs
Even though Paralomis looked like a crab, it belonged to a different group: Anomura. This group includes things like hermit crabs and coconut crabs (which some consider creepy). Despite their crab-like shape, they’re actually distant relatives of lobsters and shrimp.
The Crab Copycats
For some reason, crustaceans consistently evolved to look like crabs. Scientists call this phenomenon “carcinization.” Essentially, nature seems to think crabs are a winning design, so it keeps making them.
The First Crustaceans
The earliest crab-like creatures date back 365 million years. They were part of a big group called decapods (which means “ten legs”). This includes shrimp, crayfish, lobsters, and crabs—both real and fake ones.
True vs. False Crabs
Around 260 million years ago, decapods split into two groups: true crabs (Brachyura) and false crabs (Anomura). The oldest true crab, Eoprosopon, lived 185 million years ago. Although it exhibited some traits that were unusual for crabs, new research confirmed its legitimacy.
The First Fake Crab
On the other hand, the oldest ‘false crab’, Platykotta, lived around 200 million years ago. It looked more like a lobster, but over time, its relatives evolved into crab-like forms. Both real and fake crabs have appeared throughout history.
The Evolution of Crabs
Again and again, crustaceans started as long-bodied creatures like lobsters, only to evolve into rounder, flatter, crab-like shapes. But why? Scientists have been trying to figure this out for over 100 years.
Why Crabs?
One of the first scientists to notice this was Lancelot Alexander Borradaile in 1916. He named the process “carcinization.” He described how the lobster-like tail (pleon) shrinks over time while the front of the body grows wider and flatter.
The Crab Boom
In the Mesozoic Era (252–66 million years ago), there was a massive explosion of crab-like species. The Cretaceous period, in particular, saw the rise of many modern crabs. Scientists even call it the “Cretaceous Crab Revolution.”
The Perks of Being a Crab
Crabs seem to have a lot of advantages. Their round, flat bodies make them great at walking, swimming, burrowing, and even climbing trees (yes, nightmare fuel). Lobster-shaped animals, on the other hand, are usually stuck swimming or scuttling around.
Survival of the Crabbest
Another reason for the crab shape? Survival. Crabs lost their long tails, making them harder for predators to grab. With better mobility and fewer weak spots, they had an evolutionary edge, making the crab form very succes”Why Evolution Keeps Crabbing Its Style”sful.
Why Evolution Keeps Crabbing Its Style
So, why does evolution love crabs? Their shape is flexible, mobile, and hard to catch. That’s why so many crustaceans independently evolved to look like them. Fake crabs, real crabs—it doesn’t matter. Being a crab is the way to go.
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