164
The Migrant Biota
Ocean, Senegal and the Caribbean Sea; or Eunice torquata reported from Lebanon, Israel, Sinai, Elat, and also from South Africa, Angola and Cameroun. The
above authors, speaking of Pista cristata-also known from the Indian Ocean
and the Southem Atlantic and now reported from Musseri-state that: "c'est
maintenant Pista cristata qui y fait son entree offieielle (en mer Rouge), venant
probablement de la Mediterranee".
The case of Aspidosiphon mülleri, an Atlantic-Mediterranean and Pacific speeies of sipunculid, is interesting. The speeies was found in the Gulf of Aden (Bay of
Tadjourah) by Herubel (1904). Fischer (1914) found in Herubel's specimens the
same arrangement of bidentate and unidentate hooks as in the Mediterranean
specimens. He thus wrote: "It can therefore be conc1uded with certitude that tbis
species migrated from the Mediterranean into the Red Sea". I had the opportunity to check Fischer's type of spinulation on some specimens of A. mülleri from
the Mediterranean coast of Israel identified by Wesenberg-Lund (1957 a) and they
did not conform to the above statement (Por, 1973b, 1975c).
Several hydroids listed by H.-E. Schmidt (1971), such as Thbularia larynx,
Tubularia mesembryanthemum, and Ventromma halecioides are known from the
Pacific as tropicopolitans. Schmidt himself stated, regarding these cases, that "the
conc1usions ... ab out this migratory route (i.e. through the Suez Canal) may cause
some discussion". It does indeed.
5. Finally, there are several speeies in which the previous identification has
been questioned. There are also a few cases insufficiently documented. For the
sake of completeness these cases are also listed.
I dwelt on purpose in such length on the cases which can somewhat crudely be
called "Anti-Lessepsian" migrants. The argument is very important for the whole
purpose of the present book.
One cannot expect a hermetically unidirectional phenomenon in natural processes involving a wealth of diverse taxa. The most which can be said is that the
Lessepsian migration has an "almost exc1usively one-way character" (Por et al.,
1972). The "Anti-Lessepsian" counterpart is a different process, which cannot be
compared to that ofLessepsian migration.
Insofar as Lessepsian migration involves gradual advance and spreading and
finally a successful accommodation of the migrants in an alien zoogeographical
region, there are differences with the species which went the opposite way:
1. There is a gradual advance of Mediterranean speeies southwards through
the Canal, although to a relatively limited extent. A few Mediterranean speeies
reached the surroundings of Suez, but did not colonize the open Gulf of Suez. The
few exceptions, two or more, are euryhaline Mediterranean fish speeies which
have established themselves in or around the lagoons of the Gulf of Suez.
2. All the other cases of Anti-Lessepsian migration are known from animal
groups in which passive transport on throughgoing ships is the rule. If the distributional facts in the field, in most cases incomplete, will further support the
assumption of transport through the Canal, there is still nothing peculiar about it.
Passive transport on ships is a worldwide _phenomenon whereby speeies have
crossed the Oceans in every possible sense.
In short, the Anti-Lessepsian migration, in the few cases in which it has
occurred, cannot be compared to Lessepsian migration proper. It is merely a
The Migrant Biota
Ocean, Senegal and the Caribbean Sea; or Eunice torquata reported from Lebanon, Israel, Sinai, Elat, and also from South Africa, Angola and Cameroun. The
above authors, speaking of Pista cristata-also known from the Indian Ocean
and the Southem Atlantic and now reported from Musseri-state that: "c'est
maintenant Pista cristata qui y fait son entree offieielle (en mer Rouge), venant
probablement de la Mediterranee".
The case of Aspidosiphon mülleri, an Atlantic-Mediterranean and Pacific speeies of sipunculid, is interesting. The speeies was found in the Gulf of Aden (Bay of
Tadjourah) by Herubel (1904). Fischer (1914) found in Herubel's specimens the
same arrangement of bidentate and unidentate hooks as in the Mediterranean
specimens. He thus wrote: "It can therefore be conc1uded with certitude that tbis
species migrated from the Mediterranean into the Red Sea". I had the opportunity to check Fischer's type of spinulation on some specimens of A. mülleri from
the Mediterranean coast of Israel identified by Wesenberg-Lund (1957 a) and they
did not conform to the above statement (Por, 1973b, 1975c).
Several hydroids listed by H.-E. Schmidt (1971), such as Thbularia larynx,
Tubularia mesembryanthemum, and Ventromma halecioides are known from the
Pacific as tropicopolitans. Schmidt himself stated, regarding these cases, that "the
conc1usions ... ab out this migratory route (i.e. through the Suez Canal) may cause
some discussion". It does indeed.
5. Finally, there are several speeies in which the previous identification has
been questioned. There are also a few cases insufficiently documented. For the
sake of completeness these cases are also listed.
I dwelt on purpose in such length on the cases which can somewhat crudely be
called "Anti-Lessepsian" migrants. The argument is very important for the whole
purpose of the present book.
One cannot expect a hermetically unidirectional phenomenon in natural processes involving a wealth of diverse taxa. The most which can be said is that the
Lessepsian migration has an "almost exc1usively one-way character" (Por et al.,
1972). The "Anti-Lessepsian" counterpart is a different process, which cannot be
compared to that ofLessepsian migration.
Insofar as Lessepsian migration involves gradual advance and spreading and
finally a successful accommodation of the migrants in an alien zoogeographical
region, there are differences with the species which went the opposite way:
1. There is a gradual advance of Mediterranean speeies southwards through
the Canal, although to a relatively limited extent. A few Mediterranean speeies
reached the surroundings of Suez, but did not colonize the open Gulf of Suez. The
few exceptions, two or more, are euryhaline Mediterranean fish speeies which
have established themselves in or around the lagoons of the Gulf of Suez.
2. All the other cases of Anti-Lessepsian migration are known from animal
groups in which passive transport on throughgoing ships is the rule. If the distributional facts in the field, in most cases incomplete, will further support the
assumption of transport through the Canal, there is still nothing peculiar about it.
Passive transport on ships is a worldwide _phenomenon whereby speeies have
crossed the Oceans in every possible sense.
In short, the Anti-Lessepsian migration, in the few cases in which it has
occurred, cannot be compared to Lessepsian migration proper. It is merely a