A research team discovered four purple crab species on the island of Palawan in the Philippines.

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Palawanense Insulamon is the name of the freshwater crab species in the picture. This is a male crab. During the day, Insulamon palawanense snuggled in the mud and at night they rose to search for food.

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Hendrik Freitag, a researcher at the Senckenberg Animal Museum in Germany, and students from Manila University, Philippines, found four new crab species on the Philippine island of Palawan. The team thinks that purple on the crab's body is the result of natural evolution. Purple helps the crabs recognize their fellow types more easily.

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Insulamon johannchristiani, another newly discovered variety of crabs, is also purple.

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But the males Insulamon johannchristiani have a high position in the flock that possesses a red appearance.

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The crab Insulamon magnum is quite large in size, with a body width of about 53mm. In Latin language, "magnum" means "big".

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One crab Insulamon magnum is carrying eggs. All four new crab species are more threatened than other freshwater crabs because they only live in streams and small rivers, Hendrik Freitag said.