The photography of deep-sea echinoderms provides information on population density, spatial distribution, method of locomotion, feeding behaviour, faecal density (in the case of holothurians), burrowing behaviour, and the degree to which echinoderms bioturbate the sediment surface. Photographs taken between 400 and 4100 m in the Porcupine Seabight off the southwest coast of Ireland have provided information on these features of echinoderm life. The population density of the common echinoderms visible in photographs rarely exceeds 1000 individuals per hectare (e.g. Phormosoma placenta, Benthogone rosea) apart from some exceptional cases, such as Elpidia echinata. Although most epifaunal echinoderms crawl over the seabed with remarkably little disturbance of the sediment surface, some species, such as Bathybiaster vexillifer, plough through the upper centimetre of the sediment, and other species cause disturbance while burrowing.