1063-0740/02/2804- $27.00 © 2002
Russian Journal of Marine Biology, Vol. 28, No. 4, 2002, pp. 267–269.
Original English Text Copyright © 2002 by Biologiya Morya, Zamponi.
Symbiotic relationships between cnidarians and
representatives of other animal groups have been dis-
cussed in numerous publications. However, informa-
tion about such relationships on the continental shelf of
Argentina is conﬁned to a few papers published by
. [5–8, 19].
The ﬁrst record of an association between cnidari-
ans and representatives of other invertebrate taxa in the
seas of Argentina (Buenos Aires Biogeographical Prov-
ince) was published by Zamponi  for the anemone
Carlgren, 1949 and the spider
H. Milne-Edwards, 1934. Later
on, Pastorino  described for the ﬁrst time the asso-
ciation between this anemone species and the gastro-
in coastal waters of Patagonia.
Phillips et al.  mentioned records of the crabs
Milne-Edwards, 1934 in an anemone of
, which is closely related to
, and suggested that the crabs penetrated into
the cavities of the medusa when the latter is on or near
the bottom. Vaz Ferreira  described symbiotic rela-
tionships between the crab
and a unidenti-
ﬁed medusa (Discomedusae) in the waters of Uruguay.
Later on, this medusa was identiﬁed as
The ﬁnding of an association between
in the coastal shallow waters of Argen-
tina extends our knowledge and supplements informa-
tion published elsewhere.
MATERIALS AND METHODS
In this type of study, it is usually difﬁcult to ﬁnd
many specimens of the medusa
they enter coastal waters only under abnormal environ-
mental conditions (weather, current, etc.) that alter their
common distribution pattern. Therefore, only few spec-
reach inshore coastal waters.
The material for this paper (four medusas) was col-
lected in shallow coastal waters (from a depth of 0.8 m
deep), at the mouth of the Mar Chiquita Estuary
W). The water temperature and salin-
ity was 22.5
N and 34‰, respectively. The collected
specimens were identiﬁed using information from [2, 3,
11, 12]. The collected medusas were measured for the
sizes of all four subgenital pockets and the sex was
determined (Table 1). To determine the sex, a small
piece of gonadal tissue was macerated and examined
with an Axiolab trinocular phase microscope. The crabs
were measured for the length and width of
the carapace. The sex of the crabs also was determined
(Table 2). The determination of the sex was determined
by taking into account the size of the somites of the
pleon. All measurements are provided in mm.
The size of subgenital pockets in
size of crabs
were registered to determine
possible correlations between the size of the crab and
the dimensions of its refuge.
The Association between Medusa
(Scyphomedusae, Rhizostomeae) and Decapod
(Brachyura, Majidae) Recorded for the First Time
in Neritic Waters of Argentina
M. O. Zamponi
National University Mar del Plata, Funes 3250 (7600), Argentina
Received September 23, 2001
—The paper discusses the ﬁrst record of the association between the medusa
Haeckel, 1880 and the decapod
Milne-Edwards, 1934 in neritic waters of Argentina. Our results
allow us to conclude that the symbiotic relation between these two species is a common phenomenon. The crab
is located in the subgenital pockets of
such that one-half of its cephalothorax is exposed
to the outside. The crabs feed at the expense of the medusa, ingesting some portion of its food. A few specimens
of the crab have been found, mostly females; the only male was of a somewhat larger size.
symbiosis, commensalism, crab
This article was submitted by the author in English.