This stunning species of tiny, colourful crustacean has only been found in the Philippines, exclusively in the Palawan island group. Previously, only one species within the Insulamon genus was known. A study released in 2012 by Hendrik Freitag of the Senckenberg Museum of Zoology in Dresden, Germany has described four new species in the Insulamon Genus.
The four species discovered in 2012 range between about an inch or 2.5 centimetres to 2 inches or 5.3 centimetres wide and feature a striking purple colour on their shell.
Extensive investigations into the freshwater crabs in the area began back in the late 1980’s. At this time one species within the Insulamon genus was found – the Insulamon Unicorn. This means there’s now a total of five known species within the Insulamon genus found in the Palawan island group.
The biggest of the four new species Is the Insulamon Magnum followed by the Insulamon Palawenese and the Insulamon Johannchristiani. Then the smallest of the species is the Insulamon Porculum.
The Insulamon features and habitat
The species feature a distinct purple shell with red tips on its legs and claws. There are many theories as to why the crabs have developed the vibrant purple colour on its shell.
First, there is the possibility that it serves no purpose at all, it may have just evolved by chance. Another theory is that it serves as a visual signal for the crabs to recognise their own species. It is known that crabs can recognise and react to colour. This does add to the credibility of the shell colour having a signal function.
This theory could help explain colour variations between the Insulamon species. The large males within the species generally appear more reddish as opposed to the immature males and females who appear in a more violet tone.
The Insulamon species seems to be endemic to the Palawan island group. They are mostly found in small, lowland-forest ecosystems. The discovery of this species adds to the Philippines standing as one of 17 countries which are home to most of the earths animal life.
The Insulamon are semi-aquatic, they burrow along the banks of streams, as well as usually being found under boulders and roots. The crabs emerge at nights, entering the water to forage. They feed on dead plants, fruit and small animals.
The Insulamon face many threats to their existence. They are prey to reptiles, birds and other mammals, as well as local populations in remote areas of Palawan collecting them for food. The Insulamon also face threats to their habitat. This is due to deforestation relating to farming, mining and the construction of housing. They also face water pollution due to heavy industry operating on the island.
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