The present study described the abundance, body length, gonadal development stage and feeding behavior of Parasagitta setosa in the southern Black Sea, Turkey. The study was conducted twice a month from January 2008 to December 2008 by vertical hauls with a 112 μm mesh size plankton net in the 0 – 50 m column of a neritic area of Sinop. During the study period, the abundance values of this species were generally low, varying between 10 and 980 ind.m-2. P. setosa occurred in small numbers from December to July, but became numerous from August onwards. 1580 animals 0.53 to 12.8 mm in size were dissected. Food items found in the guts of 53 individuals (3.4%) indicated that the diet of this species is primarily composed of copepods (54.73%). The food-containing ratio and number of prey items per chaetognath were low values. A greater number of individuals possessed a size class of 1 – 1.99 mm and 2 – 2.99 mm; these two length classes combined comprised 62% of the total sample. Four different development stages were determined by using ovary and seminal vesicle development. Stage I (immature) dominated the population of P. setosa.