In bad weather, or if a strong wind prevented him from painting outside, Van Gogh often painted still lifes. He may have come upon the idea of painting this crab after seeing Japanese prints of the same subject.
He devoted close study to the effect of light and shade on the crab’s shell, representing the shading as in a drawing, with short dashes. Painted in what – for him – was considerable detail, the crab seems to be moving in a deep green sea of brushstrokes.