A total of 722 ophiuroids belonging to the species Ophioderma januarii and Ophioplocus januarii was collected on the coast of the State of São Paulo, from October 1985 to July 1987. Measurements of disc diameter of the specimens were ranged from 10,5 to 21,5 mm for Ophioderma januarii and from 2,6 to 21,5 mm for Ophioplocus januarii External morphological characteristics of the individuals were observed and growth series were organized to detect possible changes. For Ophioderma januarii variations were found in the shape of the shields, in the number of oral papillas and arms spines, in the color of the dorsal disc surface and in the dorsal arm plates. On Ophioplocus januarii variations were found in primary scales, in the major scales series of the dorsal interradial region of the disc, in the number of scales between the central plate and the edge of the disc, in the shape of the radiais and orals shields, in the number of the oral papillas, in the color of the dorsal disc surface and in the dorsal arm plates. Analyses of environmental parameters show that both species were present in areas with distinct environmental conditions. Ophioderma januarii was collected in the coastal region and as far as 36 m deep and Ophioplocus januarii from 30 to 100 m deep.
Morphology; Vertical distribution; Abiotic factors; Ophiuroidea; Ophioderma januarii; Ophioplocus januarii; Ubatuba: SP; Brazil