Morphologically and microscopically identification of sea cucumbers in the tidal zone of the western coast of the Persian Gulf

Abstract The morphological identification and investigation of the internal skeletal structure of sea cucumbers in the tidal zone of the western coast of the Persian Gulf were performed by sampling from 2 stations (Bostaneh Port and Hendurabi Island). Species identification were performed using the Spicules detected form muscle tissue of the samples by Invert microscope and checked with valid identification keys. Finally, after morphological and microscopic studies four species of sea cucumbers were identified. In the present study Stichopus horrens and Stichopus monotuberculatus were found for the first time in the tidal zones of the western coasts of the Persian Gulf (Hendurabi Island). This study showed that the most frequent types of spicules were barrel and button types in the sea cucumbers genus of Holothuria parva and Holothuria arenicola respectively. The characteristic feature for distinguishing of S. horrens species from the S. monotuberculatus species was the presence of large table thumbtack shape on the dorsal papilar part of S. horrens species whereas this type of spicule was absent in the S. monotuberculatus species.