Species Diversity in the Suez Canal
79
There are no Octocorallia in the Canal and from the rich fauna of Actinaria
from the adjacent seas only four species settled in the canal by 1924 (Carlgren,
1927). One of these is the swimming sea-anemone Boloceroides hermaphroditica
from the Red Sea, a highly mobile species.
The whole range of species connected with the coral reefs is consequently
lacking from the Suez Canal. Barash and Danin (1972) give a whole list of missing
families of molluscs: Architectonidae, Cypraeidae, Cymatiidae, Bursidae, Coralliophilidae, Mitridae, Conidae, Terebridae, and Tridacnidae. There are very few
species of Polyplacophora, probably only one Scaphopod and not more than
three species of Cephalopoda reported in the Canal. Here again the combination
of salinity and edaphic conditions plays the principal role.
There are few species of Opisthobranchia in the Canal; however, some of them
appear in great numbers, like the two species of Berthellina, Bursatella leachi
savigniana (= N otarchus savignyi) and Archidoris O'Donoghuei. These are species
living among the abundant growths of Halophila and the sponges which are
associated with the creepers of this marine water plant.
Barash and Danin (1972) point out the interesting fact that in the Suez Canal
there is a predominance of the number of species of Bivalvia over that of Gastropoda, despite the fact that in every sea the snails are usually more numerous than
bivalves. This abnormal relation between the species diversity of the two main
molluscan classes appears in all the collections made in the Canal since Tillier
and Bavay (1905). The reason for this must be sought in the prevalence of the
sedimentary bottoms over the hard bottoms.
At the other end of the animal kingdom, among the benthic Copepoda Harpacticoida, Por and Marcus (1972) remark that a whole array of rock-dwelling
families are missing from the Canal waters: the Tegastidae, Peltidiidae, Porcellidiidae and to a great extent, the Tetragonicepsidae.
Generally speaking the Suez Canal environment is ideal for shallow mixedbottom species. Among the molluscs, and more particularly gastropods, species
living in the badly sorted soft bottoms of sandy-mud, such as Murex anguliferus,
Murex tribulus, Fusinus marmoratus, Cerithium scabridum, and Strombus tricornis
are extremely numerous in the Canal. In Gruvel's (1936) very detailed description
ofthe soft-bottom associations ofLake Timsah, there are several species of lamellibranchs which appear in "quantites industrielles": Gafrarium pectinatum, Callistaflorida, Tapes decussatus, and Mactra olorina. Among the crabs, the Leucosiidae, a family typical of mixed bottoms are well represented by three species.
In the mixed and muddy bottoms of the Lakes several echinoderms are frequent, Synaptidae among the sea-cucumbers (3-4 species), Astropecten polyacanthus and several species of small brittle star (see also Beets, 1953).
Robinson (1927b) reports the Enteropneust Dolichoglossus gurneyi as inhabiting the shallow muddy bottoms of Lake Timsah sometimes in "enormous numbers". As already reported above, Branchiostoma lanceolatum is extremely abundant on the different types of sediment found in the Canal sectors, but not in the
Lakes. Among the smaller benthos, Nematoda, Polychaeta, and Cumacea are
very common, being typical for mixed bottoms. Among the harpacticoid copepods the level bottom species of the Cannuellidae, of the genus Stenhelia, as weIl as
the very eurytopic mud-Ioving Typhlamphiascus confusus are very frequent.
79
There are no Octocorallia in the Canal and from the rich fauna of Actinaria
from the adjacent seas only four species settled in the canal by 1924 (Carlgren,
1927). One of these is the swimming sea-anemone Boloceroides hermaphroditica
from the Red Sea, a highly mobile species.
The whole range of species connected with the coral reefs is consequently
lacking from the Suez Canal. Barash and Danin (1972) give a whole list of missing
families of molluscs: Architectonidae, Cypraeidae, Cymatiidae, Bursidae, Coralliophilidae, Mitridae, Conidae, Terebridae, and Tridacnidae. There are very few
species of Polyplacophora, probably only one Scaphopod and not more than
three species of Cephalopoda reported in the Canal. Here again the combination
of salinity and edaphic conditions plays the principal role.
There are few species of Opisthobranchia in the Canal; however, some of them
appear in great numbers, like the two species of Berthellina, Bursatella leachi
savigniana (= N otarchus savignyi) and Archidoris O'Donoghuei. These are species
living among the abundant growths of Halophila and the sponges which are
associated with the creepers of this marine water plant.
Barash and Danin (1972) point out the interesting fact that in the Suez Canal
there is a predominance of the number of species of Bivalvia over that of Gastropoda, despite the fact that in every sea the snails are usually more numerous than
bivalves. This abnormal relation between the species diversity of the two main
molluscan classes appears in all the collections made in the Canal since Tillier
and Bavay (1905). The reason for this must be sought in the prevalence of the
sedimentary bottoms over the hard bottoms.
At the other end of the animal kingdom, among the benthic Copepoda Harpacticoida, Por and Marcus (1972) remark that a whole array of rock-dwelling
families are missing from the Canal waters: the Tegastidae, Peltidiidae, Porcellidiidae and to a great extent, the Tetragonicepsidae.
Generally speaking the Suez Canal environment is ideal for shallow mixedbottom species. Among the molluscs, and more particularly gastropods, species
living in the badly sorted soft bottoms of sandy-mud, such as Murex anguliferus,
Murex tribulus, Fusinus marmoratus, Cerithium scabridum, and Strombus tricornis
are extremely numerous in the Canal. In Gruvel's (1936) very detailed description
ofthe soft-bottom associations ofLake Timsah, there are several species of lamellibranchs which appear in "quantites industrielles": Gafrarium pectinatum, Callistaflorida, Tapes decussatus, and Mactra olorina. Among the crabs, the Leucosiidae, a family typical of mixed bottoms are well represented by three species.
In the mixed and muddy bottoms of the Lakes several echinoderms are frequent, Synaptidae among the sea-cucumbers (3-4 species), Astropecten polyacanthus and several species of small brittle star (see also Beets, 1953).
Robinson (1927b) reports the Enteropneust Dolichoglossus gurneyi as inhabiting the shallow muddy bottoms of Lake Timsah sometimes in "enormous numbers". As already reported above, Branchiostoma lanceolatum is extremely abundant on the different types of sediment found in the Canal sectors, but not in the
Lakes. Among the smaller benthos, Nematoda, Polychaeta, and Cumacea are
very common, being typical for mixed bottoms. Among the harpacticoid copepods the level bottom species of the Cannuellidae, of the genus Stenhelia, as weIl as
the very eurytopic mud-Ioving Typhlamphiascus confusus are very frequent.