Sea sticklebacks (Spinachia spinachia) building a nest, coloured historical artwork. Sea sticklebacks, otherwise known as 15-spined sticklebacks, can be found in weedy, shallow coastal seas off north-western Europe. They live singly or in pairs and feed on small invertebrates. Here, the male can be seen building a nest from young seaweed, in which the female will lay her eggs. Little by little the seaweed will cover her eggs as it grows, thus keeping the eggs secure until they hatch. This is important as the female will die shortly after laying her eggs there.