Most Pycnogonida or sea spiders of the tropical, coastal seas are very small (1-2 mm body length) and have cryptic habitats in the phytal zone or close to coelenterates, sponges and other benthic organisms (Arnaud & Bamber 1987). In the present paper we examine nine species of pycnogonids found at different infralittoral habitats in the area of Sta. Marta at the Caribbean coast of Colombia. The last comprehensive study on the pycnogonids of this area is by Müller (1990) with the description of 50 species, including seven new to science (see