Crab fossils date back to the Jurassic period, some 170 million years ago.
However, the first crabs were not like current crabs. They possessed long tails and narrower, flatter shells.
Later, evolved a modern body plan with a tucked tail for protection & a wider, flatter shell for increased surface area for swimming and walking.
Scientists are unsure of the exact cause of crab body design evolution, but believe it is due to its numerous benefits.
This diversified group today includes over 6,000 species of crustaceans, ensuring a diverse range of living conditions globally.
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