Single species crabs depend on different camouflage techniques depending on which habitat they live in, new research shows.
The University of Exeter researchers compared color patterns of ordinary shore crabs ( Carcinus maenas ) from rock pools to those living on mudflats.
They found that mudflat crabs closely matched the appearance of the mud they live on, while rock pool crabs did not match the background, but instead relied on "disturbing staining ̵
1; the use of high contrast patterns to break the look of the body map."
Shore crabs are the most common crab found on Britain's shores, known to anyone going to rockpooling, and the crabs studied in this study came from six places in Cornwall.
"The crabs are very variable in color and pattern and are often extremely difficult to see," said Professor Martin Stevens of the Center for Ecology and Conservation at the University of Exeter's Penryn Campus in Cornwall.
"We used image analysis to simulate predators (birds and fish) to test how shore crabs camouflage them.
" As we predicted, rock pool individuals had significantly higher levels of disturbance, and this seems to be an effective way to spoil the body's disposition in the complex rock pool backgrounds where it is not often possible to compare the color of the environment.  Scratch & camouflage tricks revealed "title =" A rock pool crab Credit: Martin Stevens "/>
A rock pool crab Credit: Martin Stevens
"In contrast, mud flats matched closely to the mud in terms of color, brightness and pattern, but lacked contrast-disturbing markings that could give them away in the uniform mudflat environment."
Although much of the work has investigated the use of disturbing and background matching camouflage, most of this has been accomplished in artificial systems. The work here tests different use of camouflage types of real animals in different habitats.
"Crabs are often supposed to be boring and green, but they can actually be extremely colorful, and each person can look quite different. Part of the way to explain why shore crabs are so diverse," says Professor Stevens.
The paper, published in the journal Scientific Reports has the title: "Background Match and Disturbing Color as Habitat-Specific Camouflage Strategies."
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More Information: Scientific Reports (2019). DOI: 10,1038 / s41598-019-44349-2
University of Exeter
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