Chaetognaths are elongated, slender, silindirical shaped and bileterally simetrical mostly zooplanktonic organisms. Their length change between 2 and 100 mm. Their bodies are consisted of three segments: head, trunk and tail. They have gasping spines and tooth on each sides of the head, there is a pair of eyes in the dorsal part of the head and corona cilliata streching onto the trunk part. There are gut diverticule, collerette, ventral ganglion, ovarium, anterior fins and part of posterior fins in trunk. In the caudal area there is another part of posterior fins and a pair of seminal vesicles. These characters show difference among chaetognath species and they are also used to characterize the species. A few studies were done about chaetognaths of Turkey coast in the literature so this study is aimed to be a written source for the systematic investigation of chaetognaths.