1063-0740/05/3102- © 2005 Pleiades Publishing, Inc.
Russian Journal of Marine Biology, Vol. 31, No. 2, 2005, pp. 78–90.
Original English Text Copyright © 2005 by Biologiya Morya, Islam, Machiko, Shokita.
The family Portunidae is a distinctive group of
marine crabs, which are well represented in Southeast
Asia. The genus
is the largest genera in the
subfamily Portuninae with more than 66 species known
to date from the Indo-West Paciﬁc region [16, 17, 21].
The habitat of
from muddy to rocky shores within the intertidal zone
and is commonly found under coral heads of reef ﬂats
. This species is widely distributed in the Indo-West
Paciﬁc and is known in China, Japan, Malaysia, Sin-
gapore, Indonesia, and Australia [4, 5].
Within the genus
, complete zoeal devel-
opment has been studied in detail by Thomas
(Latreille) from India; by Fielder and
Greenwood  on
Stimpson from Australia;
by Terada  on
(Herbst), and by Kurata
 and Terada  on
H. Milne Edwards from
Japan. Until now, the complete larval development of
has been unknown. The objective of this
study was to describe and illustrate all the larval stages
in detail and to compare them with previ-
ously known larvae of other species of
MATERIALS AND METHODS
crab was captured
by gill net from the nearshore area of Mizugama Bay,
Okinawa Island (26
E), Japan, on May 5, 2000. The crab was
brought to the Laboratory of Fisheries Biology, Univer-
sity of Ryukyus, Okinawa, and maintained in a plastic
trough containing seawater of 34
1‰ salinity and
C temperature with moderate aeration to supply
air and to circulate the seawater. The seawater was
changed daily until hatching. The female was fed with
small dry ﬁsh (
) and the meat of
short-necked clam (
Hatching occurred within 10 days after collection.
Among the hatched larvae, the most photopositive
zoeae were mass-reared under the same conditions as
the female, using a gently aerated 10-liter capacity
plastic bowl. Zoeae were fed daily with newly hatched
sp. In addition, ﬁnely chopped meat
of the short-necked clam (
) was fed to
the megalopa. Water and food were changed daily, and
the larvae were checked for molting. Salinity was
obtained by dilution of ﬁltered natural seawater (35‰)
from the Nakagusuku Bay, Okinawa, with dechlori-
nated tap water.
Specimens used for dissection and identiﬁcation of
stages was preserved in a 50% ethylene glycol solution.
Larvae were dissected under a stereomicroscope
(Nikon SMZ-10) by using ﬁne entomological needles.
Drawings and measurements were made with a proﬁle
projector (Nikon Proﬁle Projector V-12) and a com-
pound microscope (Nikon FDX-35) equipped with a
drawing tube. At least 5 specimens of each stage were
Larval Development of the Swimming Crab
Montgomery, 1931 (Crustacea: Brachyura: Portunidae)
Reared in the Laboratory*
Md. Sirajul Islam, Kaneda Machiko, and Shigemitsu Shokita
Department of Chemistry, Biology and Marine Science, Faculty of Science, University of Ryukyus,
1 Senbaru, Nishihara, Okinawa 903-0213 Japan
—The larval development of the swimming crab
Montgomery was studied from
the ﬁrst zoea to megalopa under laboratory conditions. Five zoeal stages and one megalopa are identiﬁed, and
detailed descriptions and illustrations are provided for each stage. At an average salinity and temperature of
1‰ and 24
C, the megalopa was attained 17 days after hatching. Morphologically, the ﬁrst zoea of
is similar to those of other species of
in having a lateral spines on the carapace, one plus
six setae on the endopod of the maxillule, two plus four setae on the endopod of the maxilla, and three pairs of
serrate setae on the posterior margin of the telson furca. The differences between the ﬁrst zoea and megalopa
and those of its congeners are discussed brieﬂy.
larvae, megalopae, development.
* This article was submitted by the authors in English.