How the crab became a wild animal: Fossil amber offers new clues

“Perhaps the biggest challenge has been the regulation of osmosis,” Heather Bracken-Grissom says. It is intended to regulate the solutes in cells. Additionally, crabs encountered a large number of new predators on land, which was a welcome addition to the list.

Despite all these adversities, the Crabs continued to try to gain a foothold on Earth. Today’s crabs have invaded many different habitats: beaches, coral reefs, the depths of the ocean, as well as inlets, rivers, and freshwater lakes. Some of them – such as the Caribbean Halloween crab – spend most of their lives on land. Palm thief, whose weight can reach 4 kilograms, lives in trees on the islands of the Indian and Pacific Oceans.

Researchers who specialize in creating family trees based on biomolecules – for example genes – estimate that the first terrestrial crabs were present. 130 million years ago It was developed in the early Cretaceous period. The oldest known lobster fossils so far are around 70 million years old, but an amber fossil from Myanmar has now broken that record.

From salt water to fresh water

While the amber crab is the oldest known land crab, it likely wasn’t the first or the last to leave the sea. “We assume that crabs have made at least six attempts in their evolution to survive in freshwater regions and at least a dozen attempts to expand their habitat to brackish water,” says Javier Luque.

In addition to crabs, there are other creatures that have turned their backs to the sea to move inward. The rainbow trout that lives in Lake Michigan are descended from the fish that live inside Less than 120 years old They moved their habitat from salt to fresh water. Several species of whales and dolphins – including the Amazon dolphin – also left the ocean at some point.

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Since the transition from salt water to fresh water does not only occur in animals, it is even more surprising how many times this step has been taken in the evolution of different species. With Kretzpara As a link between the beginning and end of this process, scientists now have a new starting point to better understand the process.

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