Polychaetes, or bristle worms, are a very common and diverse class of worms with over 10,000 species described so far. Commonly overlooked, these mostly marine worms can be brightly coloured and are to be found in tubes and burrows in the sand and mud of the beach to the depths of the ocean or even just free-living in the water. They all have bristles on their segmented bodies - in fact 'polychaeta' means 'many bristles'. They come in an impressive range of sizes from just 1mm to 3m long.

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