Nematocysts of Rhopilema nomadica (Scyphozoa: Rhizostomeae), an immigrant jellyfish in the eastern mediterranean.

Rhopilema nomadica-a recently discovered scyphomedusa in the eastern Mediterranean-is considered a lessepsian migrant. Its nematocysts were extracted from the scapular and mouth-arm tentacles and examined using light and electron microscopy techniques. The morphometric parameters of the nematocysts were measured before and after complete discharge. Three categories of nematocysts were identified: heterotrichous isorhiza haploneme, holotrichous isorhiza haploneme, and heterotrichous microbasic eurytele. The relative abundance of the nematocysts and their occurrence in tissues of the jellyfish were noted. A brief discussion concerning the classification of certain types of nematocysts is given. A comparison with the available data on other Rhopilema species revealed that the nematocyst categories of R. nomadica are more similar to those of the Atlantic R. verrilli than to those of the Western Pacific R. esculentum. A brief comparison of the injuries caused by these species is given. © 1995 Wiley-Liss, Inc.

Ciguatera-like poisoning in the Mediterranean.

A case of group poisoning from the consumption of the fish Sarpa salpa, caught in the Mediterranean coastal waters of Israel, is presented. Mullets and rabbitfish caught at the same site caused no harm. This is the third case of ciguatera poisoning in the region and the first to be transferred by a fish which is not a Red Sea immigrant. It implies that toxic algae dinoflagellates, originating from the Red Sea, crossed the Suez Canal and found their way to the Mediterranean coastal waters.

Aspects of species recognition by sound in four species of damselfishes, genus Eupomacentrus (Pisces: Pomacentridae).

Members of four sympatric species of Eupomacentrus carry out reproductive activities at the same time of the year and produce similar pulsed courtship sounds. Such sounds are known to facilitate courtship among conspecifics. Consequently, members of the four species in the field and in the laboratory were tested with the various sounds to determine if they could distinguish their own species sounds from those produced by congeners. The differential responses clearly demonstrate species specific recognition by sound and indicate that the pulse interval and the number of pulses per sound are the important parameters for this recognition.