During a faunistic survey in the rocky intertidal of Chabahar Bay (Iranian coast of the Gulf of Oman) in 2014, Ophionereis dubia, was reported as a new species record from this locality. The details on the taxonomic and morphological features as well as on the ecology of this ophiuroid are discussed in the present study and viewed in the light of the species' new appearance at Chabahar Bay.

The present paper focuses on the first report of Ischnochiton (I.) yerburyi from Chabahar Bay, the Iranian coast of Oman. The morphological features and distribution information are considered.

This paper reports the first record of Acanthopleura vaillantii from the northern Oman Sea, Iranian coast. The specimens were collected from the intertidal zone of Chabahar Bay in June 2009. The gross morphological characters, including features of the valves and girdle armature, are described.

Community structure and biodiversity of polychaetes of the intertidal sandy beach at Chabahar Bay, the largest bay in the north-east of Oman Gulf, were studied for ten months in 2007. A total of 16 polychaete species belonging to 15 families were identified. The results showed that densities were influenced by the monsoon season so that maximum density (1370 ind m−2) was observed at pre monsoon while minimum density (117 ind m−2) was obtained during monsoon. Two species, Synelmis albini and Magelona cornuta, were the most abundant species. The highest and lowest values of diversity and richness indices were obtained at pre monsoon and during monsoon, respectively. Also, multivariate analysis separated monsoon season from pre and post monsoon clearly. Our results show that the monsoon can be the most important factor on community structure and biodiversity of polychaetes at Chabahar Bay and the intertidal of this bay is not a favourable environment for polychaete development.