Nudibranch Ocean Colouring

A nudibranch is a shell-less sea snail famous for spectacular colours and shapes. Its name means naked gills because many species breathe through a feathery gill rosette carried openly on the back. More than 3,000 species live in oceans worldwide, from tide pools and coral reefs to cold water and the deep sea. Most are small, often 1 to 10 centimetres long, though a few can grow beyond 30 centimetres. Lifespan is usually brief: many live for only several weeks or months, and some survive about one year. The two horn-like structures on the head are rhinophores, sensitive organs that detect chemicals in the water and help the nudibranch find food or a mate. Different species eat sponges, hydroids, anemones, barnacles, or other sea slugs using a file-like tongue called a radula. Without a hard shell, nudibranchs rely on clever defences. Bright colours can warn predators of a bitter or toxic taste. Some obtain defensive chemicals from the animals they eat, while others recycle stinging cells from prey and store them in body projections. Camouflaged species may match the sponge or coral beneath them so closely that they are difficult to spot. The page shows a friendly nudibranch crossing a broad reef rock. Let your imagination lead the colours. The body could be lemon yellow with purple spots, orange with blue rings, white with red patches, or turquoise with pink edges. Use one colour for the paired rhinophores and another for their ridges. The feathery gill rosette can match the main body or form a bright contrasting crown. Keep a few white highlights between the spots to make the soft skin look glossy. Colour the sponge shape orange, red, or golden brown, the seaweed green or olive, and the rock grey, tan, lavender, or rusty red. Add pale blue around the bubbles. Use short careful strokes on the gills and feelers, then broader strokes across the open body so every special feature stays crisp.

◫ A4 size✎ Bold outlines♡ Ages 3–8

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