NEWS 110
12
Juvenile
Sphaeramia nematoptera
are really gorgeously colored....
.... but they are also a sight to see when full grown (the species attains around 8 cm long).
Diadem sea urchin.
Cardinalfishes occur in all the warm seas of
the Earth. Originally the only species living
in the Mediterranean was the above-
mentioned
A. imberbis
, but in the interim a
whole series of species have migrated from
the Red Sea into the Mediterranean via the
Suez Canal, the so-called Lessepsian
migrants (after the engineer Lesseps, under
whose direction the Suez Canal was
opened in 1869)
Apogon queketti
,
A. smithi
,
Apogonichthyoides nigripinnis
,
A. pharaonis
,
A.taeniatus
,and Ostorhinchus fasciatus.The
influence of these newcomers - the
technical term is neozoa - on the
indigenous fauna of the Mediterranean
remains unknown, although the Pharaoh
Cardinalfish (
Apogonichthyoides pharaonis
)
is a direct competitor for habitat with
Apogon imberbis
and populations of
A.
pharaonis
are constantly growing (Oral,
2010). But the King of the Mullets is still
considered a common species and not
endangered, and it remains to be seen how
well
A. pharaonis
can adapt to the low
temperatures
in
the
western
Mediterranean. At present its occurrence is
restricted to the eastern Mediterranean.
Unusual relationships
It is known that many cardinalfish species
live in close association with other
creatures. Thus some species live among
the long venomous spines of sea urchins of
the genus
Diadema
. The Banggai
Cardinalfish (
Pterapogon kauderni
), already
mentioned above, is particularly well
known for this association, but the species
most highly specialized on this partner is
undoubtedly
Ostorhinchus chrysotaenia
;
this cardinalfish has even been observed to
clean the sea urchin. So the relationship is
probably a true symbiosis offering
reciprocal benefits, while the use of sea
urchins by other cardinalfishes, without the
sea urchin gaining anything, is termed
commensalism.
There are cardinalfishes (
Astrapogon
stellatus
) in the Caribbean that live inside
the mantle cavity of giant snails of the
species Lobatus gigas (formerly
Strombus
gigas
). A closely-related species,
Astrapogon
puncticulatus
, lives in the shells of dead
snails, similar to the behavior known from
some cichlids from Lake Tanganyika.
The list of the commensal associations
between cardinalfishes and invertebrates is
long. The Caribbean species
Apogon
