Research from the University of Exeter has revealed that the rock goby (Gobius paganellus), an unassuming little fish commonly found in rock pools around Britain, southern Europe, and North Africa, is a master of camouflage and can rapidly change colour to conceal itself against its background.
Whether hiding from predators or from families hunting in rock pools, the rock goby can change both its colour and brightness to match its background in just one minute.
Dr Martin Stevens from the Centre for Ecology and Conservation at the University of Exeter's Penryn Campus in Cornwall said: "Anyone who's been rock pooling will probably have encountered rock gobies, and may even have thought they could see them change colour in buckets. Our research shows that this is the case and that rock gobies can rapidly tune their appearance to match their background."
The researchers found that when gobies were photographed on a bright white or dark background, they could change their brightness accordingly. When photographed on coloured backgrounds they altered their colour, becoming either more red or blue.
Undertaking this rapid visual change should be a major advantage for the fish when trying to avoid predators. Gobies find themselves under intense predation pressure at low tide from birds and at high tide from larger fish. To remain concealed they must rapidly respond as they are pushed over many different backgrounds by tides and waves.
The researchers collected the gobies from Gyllyngvase beach in Falmouth, Cornwall then photographed them against different backgrounds over time to quantify the speed and extent of the colour change. The results show that the fish were capable of rapid visual change for concealment.
The colour change is driven by special cells in the fishes' bodies called 'chromatophores'. These are found in many animals and work to condense or spread pigments of different colour over the body, changing the appearance of the fish. This process is guided by the visual system of the goby when it moves onto a new background.
Studies of colour change for camouflage have previously been undertaken in animals including chameleons, cuttlefish, flatfish, and crabs, but rarely have studies directly quantified the changes in colour and brightness that occur, how fast this happens, and how they affect camouflage matching.
The research was supported by the Biotechnology and Biological Sciences Research Council.
The research paper: Rockpool gobies change colour for camouflage by Martin Stevens, Alice E. Lown, and Alexander M. Denton is published in the journal PLOS ONE.
About the University of Exeter
The University of Exeter is a Russell Group university and in the top one percent of institutions globally. It combines world-class research with very high levels of student satisfaction. Exeter has over 19,000 students and is ranked 7th in The Times and The Sunday Times Good University Guide league table, 10th in The Complete University Guide and 12th in the Guardian University Guide 2014. In the 2008 Research Assessment Exercise (RAE) 90% of the University's research was rated as being at internationally recognised levels and 16 of its 31 subjects are ranked in the top 10, with 27 subjects ranked in the top 20. Exeter was The Sunday Times University of the Year 2012-13
The University has four campuses. The Streatham and St Luke's campuses are in Exeter and there are two campuses in Cornwall, Penryn and Truro. In a pioneering arrangement in the UK, the Penryn Campus is owned and jointly managed with Falmouth University. At the campus, University of Exeter students can study programmes in the following areas: Animal Behaviour, Conservation Biology and Ecology, English, Environmental Science, Evolutionary Biology, Geography, Geology, History, Human Sciences, Mathematics and the Environment, Mining and Minerals Engineering, Politics and International Relations, Renewable Energy and Zoology.
The University has invested strategically to deliver more than £350 million worth of new facilities across its campuses in the past few years; including landmark new student services centres - the Forum in Exeter and The Exchange at Penryn - together with world-class new facilities for Biosciences, the Business School and the Environment and Sustainability Institute. There are plans for another £330 million of investment between now and 2016.
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