Robotic fish that can work together to detect and identify pollution in ports and other aquatic areas have been developed by scientists.
The fish are the work of Shoal, a pan-European ICT project made up of six organisations and partly funded by the European Union.
Luke Speller, project leader and a senior research scientist at the London-based BMT Group, said: "The fish can identify the source of pollution enabling prompt and more effective remedial action."
The yellow-coloured robotic fish are 1.5 metres (five feet) long and are driven by a dual-hinged tail that enables them to make tight turns.
They are battery powered and can run for up to eight hours before they need to be recharged.
Each one has a range of sensors and programming that allows it to navigate and gather information which it can share with other fish and relay back to researchers.