ISSN 1062-3604, Russian Journal of Developmental Biology, 2016, Vol. 47, No. 5, pp. 278–287. © Pleiades Publishing, Inc., 2016.
Original Russian Text © A.A. Zotin, E.F. Kirik, 2016, published in Ontogenez, 2016, Vol. 47, No. 5, pp. 296–306.
Individual Growth of the Great Ramshorn Snail Planorbarius corneus
(Gastropoda, Planorbidae) Embryos
A. A. Zotin* and E. F. Kirik
Koltsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow, 119334 Russia
Received February 10, 2016; in f inal form, April 7, 2016
Abstract—Individual growth of the great ramshorn snail Planorbarius corneus has been studied by intravital
video imaging. As has been observed, the types of growth change over the embryogenesis. The linear dimen-
sions slightly but in a statistically significant manner decrease during the stages of cleavage to blastula. Start-
ing from the stage of blastula to trochophore, the embryo diameter remains constant to commence increasing
at the stage of middle trochophore. During the larval stages (trochophore and veliger), the growth is synchro-
nous (in Dettlaffs, biological time units) for the embryos in both the same clutch and different clutches. The
growth at that time is exponential but later desynchronizes in individual clutches. The embryos in eight
clutches grew and developed slower and hatched later as compared with the remaining five egg clutches. An
accelerated growth follows an asymptomatic pattern according to the von Bertalanffy equation. A retarded
growth is describable with a linear equation. The observed differences are likely to be associated with the
number of embryos in a clutch. All types of changes in the linear dimensions observed in the great ramshorn
snail embryogenesis can be described with the same united equation.
Keywords: growth, embryos, great ramshorn snail, gastropods
Most studies of the animal growth focus either on
adults or larvae (Mina and Klevezal’, 1976; A.A. Zotin,
2009). The growth of embryos has been studied consid-
erably less frequently because of several reasons, for
example, since normal development is impossible
outside the maternal organism and the egg mem-
branes are opaque (Belousov, 2005; Gilbert, 2010).
The embryogenesis of freshwater gastropods of the
order Basommatophora is an exception in this regard.
The egg clutches of these gastropods are transparent
and available in any season of the year. The embryos
normally develop in water in a wide range of environ-
mental factors starting from the zygote and until emer-
gence from the embryonic membranes. The embryos
in a clutch develop synchronously, allowing embryo-
genesis to be concurrently studied in several embryos.
Despite the evident advantages, the studies into
embryonic development of the Basommatophora
mollusks have been rather few (Meshcheryakov, 1975;
Morrill, 1982). The situation changed in the last three
decades, which have brought about numerous papers
on the embryonic development in different species of
this order (Goldberg and Kater, 1989; Marois, 1989;
Marois and Croll, 1992; Voronezhskaya and Elekes,
1993; Goldberg et al., 1994, 2008, 2011; Croll and
Voronezhskaya, 1996; Elekes et al., 1996; Diefenbach
et al., 1998; Voronezhskaya et al., 1999, 2004; Croll,
2000; Nagy and Elekes, 2000; Cole et al., 2002; Prze-
slawski et al., 2004; A.A. Zotin and Kleimenov, 2006;
Mapara et al., 2008; Byrne et al., 2009; Filla et al.,
2009; Ebanks et al., 2010; Hiripi and Elekes, 2010;
Shartau et al., 2010a, 2010b; Ivashkin and Voronezhs-
kaya, 2011; Kudikina, 2011; etc.).
The advance in digital micro video imaging with
subsequent image computer analysis has made it pos-
sible to comprehensively study the changes in linear
dimensions of the same embryos over the entire
The main goal of this work was to study the individ-
ual growth of developing P. cor ne us embryos.
MATERIALS AND METHODS
The great ramshorn snail P. co rn e u s Linnaeus
(Gastropoda, Planorbidae) individuals from an
aquatic culture were used as parents. The egg clutches
were kept in glass dishes in a settled (for at least 2 days)
and aerated tap water (40 mL) at different tempera-
tures in the range of 17–33°C. The temperature for
keeping snails was constant for each egg clutch over the
entire embryonic development. Water was changed on
a daily basis and was not subject to chemical assay.
INVERTEBRATE DEVELOPMENTAL BIOLOGY