Journal of the Marine Biological Association of India

Some new records of hydroids from the Gulf of Aquaba with zoogeographical remarks on the Red Sea area.

Volume 13 Issue 1

Hans Eckart Schmidt

Abstract

During spring and summer 1970 hydroids were collected by diving in Eilat Bay, near Taba, Faroun (Coral Island) and Ras el Burka. In most cases live specimens were observed to get acquainted with the cultivation methods. A total of 16 species are listed. Two species, Dynamena crisioides crisioides (Billard, 1933) and Dynamena cornicina (Billard, 1933 and Vervoort, 1967), have already been recorded from the Gulf of Aqaba. Eight of them have not previously been found in the Red Sea Tubularia larynx, Tubularia mesembryanthemum, Hydractinia kaffraria, Laomedea dichotoma, Clytia hemisphaerica, Sertularella mediterranea, Kirchenpaueria pinnata, Halopteris glutinosa). A checklist of all records from the Red Sea area, including the Gulf of Aden and the Suez Canal, is added and gives a total of 64 species of which seven or more are doubtful. Four (Turritopsis nutricula. Eudendriumracemosum mucronatum, Campanularia lennoxensis, Laomedea geniculatd) are recorded from the Suez Canal only, three (Podocoryne denhami, Calicella syringa, Halopteris catharina var. articulata) from the Gulf of Aden and one {Bougaimillia ramosa) from both regions. From these it would appear that less than 50 species exist in the Red Sea. Of these only nine species {Halocordyle disticha, Campanularia gravieri, Thyroscyphus fruticosus, Dynamena cornicina, D. crisioides crisioides, Ventromma halecioides, Gymnangiumgracicaulis, G.eximium and Lytocarpusphilippinus) have been recorded more than three times. No definite conclusions can be drawn from these results.

 

The hydrographical and geographical conditions in the Red Sea are not responsible for the small number of species, this being brought about by lack of investigations and absence of records of hydroids below the 50 m. depth. No endemic hydroid has been found among the 64 species but they can be divided into three groups; Those which penetrated into the Red Sea from the Indian Ocean (Indo-Pacific species), those which probably came from the Mediterranean Sea (Atlantic and Mediterranean forms) and those which could have penetrated from both regions (cosmopolites). Kirchenpaueria pinnata belongs to the second group and has to the author's knowledge not previously been recorded from the Indo-Pacific Oceans.

Date : 30-06-1971