88
The Migrant Biota .
harpacticoids (Por and Marcus, 1972) are circumtropical or even cosmopolitan.
There are also some cases in which a circumtropieal distribution has become
evident only recently-either due to more thorough collecting, or to a taxonomie
revision. Such may be the case of the little pearl oyster Pinctada radiata which is
circumtropical according to its presence along the western shores of America and
its wide distribution in the Western Mediterranean. The fishes Carcharhinus brevipinna, Etrumeus teres, and Parexocoetus menta whieh are often considered to be
migrants from the Red Sea are, in fact, circumtropical species (Ben-Tuvia, 1971 a).
Circumafrican Species. These are species found not only in the Mediterranean
and the Red Sea, but also along the Western shores of Mrica, and some of these
species are, in fact, circumtropical. These species had ample opportunities to
reach the Mediterranean through the Straits of Gibraltar or through previous
connections of the Mediterranean with the Atlantie. Aspidosiphon elegans-a
representative of a very old genus of Sipunculida, is considered by WesenbergLund (1957b) to be amigrant through the Suez Canal. However, this species is
also known from West African shores, from whence it probably reached the
Mediterranean.
Species Not Found in the Vicinity of the CanaL Here the problem is more
complicated. There are several instances in whieh a species formerly considered to
be Atlanto-Mediterranean is also reported from the Southern Red Sea. Some of
the species of Polychaeta, reported by Fishelson and Rullier (1969) as having
migrated through the Suez Canal, have been reported from the Southern Red Sea.
The bopyrid Parathelges racovitzai reported by Codreanu (1967) from the Black
Sea as an Indo-Pacific element cannot be reasonably considered as a Lessepsian
migrant since the distance it had to cover and the extremely different conditions
to which it would have had to adapt obviously rule this out.
Schmidt (1972) reports five species of Atlanto-Mediterranean hydroids from
Elat. He considers the possibility of their having used passive transport (on ship
hulls) in order to circumnavigate the Sinai peninsula. This is, of course, a possibility whieh cannot be ruled out, although it seems much more probable that the
species are and were present in the Red Sea before the opening of the Canal.
Pre-Lessepsian Species. Although information on species distribution before
the opening of the Suez Canal is scarce, in some instances it serves to disqualify
would-be Lessepsian migrants. Such is the case of the polychaete Eurythoii complanata, a species widespread in the Indo-Pacific whieh, however, was reported
from Beirut before the opening of the Canal (Fauvel, 1955). The fish Serranus
cabrilla, an Atlanto-Mediterranean species, usually considered to be amigrant
through the Suez Canal, was reported from the Red Sea before the opening of the
Canal (Klunzinger, 1884, based on Hemprieh and Ehrenberg).
The euryhaline species, called "Isthmus species" (see above), such as Cerastoderma glaucum, Pirenella conica, Aphanius dispar, and eventually Mugil auratus
and Dicentrarchus spp., could have crossed the isthmus before the shipping channel was opened.
Ship-Fouling Fauna. As remarked in a previous paper (por, 1973 b), some of
the recently disseminated fouling organisms üf eastern origin, such as M ercierella
enigmatica and Elminius modestus were also probably carried through the Suez
The Migrant Biota .
harpacticoids (Por and Marcus, 1972) are circumtropical or even cosmopolitan.
There are also some cases in which a circumtropieal distribution has become
evident only recently-either due to more thorough collecting, or to a taxonomie
revision. Such may be the case of the little pearl oyster Pinctada radiata which is
circumtropical according to its presence along the western shores of America and
its wide distribution in the Western Mediterranean. The fishes Carcharhinus brevipinna, Etrumeus teres, and Parexocoetus menta whieh are often considered to be
migrants from the Red Sea are, in fact, circumtropical species (Ben-Tuvia, 1971 a).
Circumafrican Species. These are species found not only in the Mediterranean
and the Red Sea, but also along the Western shores of Mrica, and some of these
species are, in fact, circumtropical. These species had ample opportunities to
reach the Mediterranean through the Straits of Gibraltar or through previous
connections of the Mediterranean with the Atlantie. Aspidosiphon elegans-a
representative of a very old genus of Sipunculida, is considered by WesenbergLund (1957b) to be amigrant through the Suez Canal. However, this species is
also known from West African shores, from whence it probably reached the
Mediterranean.
Species Not Found in the Vicinity of the CanaL Here the problem is more
complicated. There are several instances in whieh a species formerly considered to
be Atlanto-Mediterranean is also reported from the Southern Red Sea. Some of
the species of Polychaeta, reported by Fishelson and Rullier (1969) as having
migrated through the Suez Canal, have been reported from the Southern Red Sea.
The bopyrid Parathelges racovitzai reported by Codreanu (1967) from the Black
Sea as an Indo-Pacific element cannot be reasonably considered as a Lessepsian
migrant since the distance it had to cover and the extremely different conditions
to which it would have had to adapt obviously rule this out.
Schmidt (1972) reports five species of Atlanto-Mediterranean hydroids from
Elat. He considers the possibility of their having used passive transport (on ship
hulls) in order to circumnavigate the Sinai peninsula. This is, of course, a possibility whieh cannot be ruled out, although it seems much more probable that the
species are and were present in the Red Sea before the opening of the Canal.
Pre-Lessepsian Species. Although information on species distribution before
the opening of the Suez Canal is scarce, in some instances it serves to disqualify
would-be Lessepsian migrants. Such is the case of the polychaete Eurythoii complanata, a species widespread in the Indo-Pacific whieh, however, was reported
from Beirut before the opening of the Canal (Fauvel, 1955). The fish Serranus
cabrilla, an Atlanto-Mediterranean species, usually considered to be amigrant
through the Suez Canal, was reported from the Red Sea before the opening of the
Canal (Klunzinger, 1884, based on Hemprieh and Ehrenberg).
The euryhaline species, called "Isthmus species" (see above), such as Cerastoderma glaucum, Pirenella conica, Aphanius dispar, and eventually Mugil auratus
and Dicentrarchus spp., could have crossed the isthmus before the shipping channel was opened.
Ship-Fouling Fauna. As remarked in a previous paper (por, 1973 b), some of
the recently disseminated fouling organisms üf eastern origin, such as M ercierella
enigmatica and Elminius modestus were also probably carried through the Suez