Chaetognaths or Arrow Worms

Abstract

The knowledge of chaetognaths in the two Costa Rican coasts is both scarce and asymmetrical. Less than 20% of the number of potential species (115) have been effectively recorded from this country. The Pacific side has been surveyed much more intensely than the Caribbean coast. This is attributed to the large zooplankton surveys in the Eastern Tropical Pacific (ETP) that included sampling sites in Costa Rican waters. These expeditions yielded relevant data to the current knowledge of the ETP region chaetognath fauna, including Costa Rica. Up to 19 species have been effectively recorded in the Costa Rican Pacific waters, about 50% of the known species richness in the ETP. Conversely, only nine species have been reported for the Caribbean waters of Costa Rica, a figure far from the 25 species known to be distributed in the Caribbean Basin. The relevance of developing zoo-plankton surveys that include a close analysis of the chaetognath fauna is emphasized in terms of the trophic relevance of these predators in the pelagic realm.