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Records of the Australian Museum (2017) Vol. 69 
is here that air, trapped from the atmosphere, is covered with 
mucus to make the bubbles of the float”. The Janthina float 
and its means of bubble formation are, therefore, among 
the most frequently described aspects of molluscan biology. 
They presumably attracted the attention of early naturalists 
because the bubble float is unique to Janthina and Recluzia , 
and living specimens of Janthina are obvious when a large 
number is cast ashore, forming a violet band on beaches. 
An excellent photograph was published by Bennett (1966: 
pi. 11, fig. 1) and others were taken by Tony Healy (Figs 
6A-B) of a living specimen of Reduzia lutea , and others 
have been taken of R. johnii by Denis Riek (Figs 7A-B). 
They show a relatively simple foot, with the float attached to 
the foot as in Janthina , and the undivided cephalic tentacles 
curled around the anterior end of the float and apparently 
aiding float retention in some situations. No epipodia can be 
distinguished in any photographs of living Reduzia specimens, 
and the head is a little smaller, proportionally, than those of 
Janthina species. The snout in Figs 6 and 7B also is seen to 
be much smaller than that of Janthina species. The float in 
these illustrations (Figs 6-7) is constructed of significantly 
smaller and more haphazardly arranged bubbles than those 
of Janthina species. This suggests the possibility that it is 
constructed in a different way from the float of Janthina 
species, but float construction has not been observed in 
Reduzia ; a propodium presumably is required to fonn float 
bubbles. A propodium appears to be shown in Fig. 6A, 
behind the long tentacle and beneath the float, separated by a 
notch from the rest of the foot and its attached mucus sheet. 
Also, the left specimen in Fig. 7B can be seen applying an 
expanded part of its anterior to the shell of the right specimen. 
This structure lies beneath (posterior to) the snout and so is 
probably the propodium. Cephalic tentacles are single (not 
subdivided) in all illustrations of living Reduzia specimens. 
The anatomy of Recluzia clearly deserves further study. One 
of the living animals shown here (Fig. 6A) has an obvious 
sheet of mucus retaining the float, located between the float, 
the foot (mesopodium) and the lower part of the penultimate 
shell whorl. Churchill etal. (2011a: supplementary table SI) 
reported a mucus stalk retaining the float in Reduzia , but a 
sheet clearly is present in Fig. 6A, apparently removing one 
distinction between Reduzia and Janthina. 
Other photographs of living Janthina specimens provided 
by Dimitris Poursanidis of specimens collected at Arina Beach, 
Heraklion, Crete, in the Mediterranean, and those by Denis 
Riek of specimens collected in northern New South Wales, 
Australia, all photographed in aquaria (Figs 4-7), reveal the 
external anatomical features of all Janthina and Reduzia 
species other than J. exigua (implying that J. exigua is a rare 
species in these areas). Specimens of J. janthina mdJ. pallida 
illustrated together (Fig. 4A) reveal the much larger, more 
randomly arranged float bubbles of J. janthina compared 
with the smaller, more uniform ones of J. pallida . Unusually 
bright pink egg capsules also are visible under the floats of 
specimens of J. pallida , whereas the egg capsules attached to 
some specimens of J. glohosa (Fig. 5E) and J. umhilicata (Fig. 
5C) are pale pink. The head views (Figs 4B-C, 5A, D) of J. 
janthina clearly show the forked cephalic tentacles, speckled 
with black in some specimens but paler to almost transparent 
in others, the protruding snout also speckled with black, the 
lack of obvious eyes and operculum, and the subdivided 
odontophore and radula, with teeth protruding from the mouth 
(Figs 4C, 5D). Lateral views of J. janthina (Figs 4D-E) also 
clearly show the triangular to almost circular right epipodium, 
with a serrated margin, and reveal its relationship to the rest 
of the foot. Epipodia are not visible in any other specimens, 
apparently because they were not in the correct orientation. 
The head-on view of J. janthina (Fig. 5 A) clearly reveals the 
raised propodium, in front of the float but behind the cephalic 
tentacles. Some idea of the external anatomy of J. pallida is 
revealed by Figure 5B, although this specimen evidently did 
not expand from its shell as readily as J. janthina does. The 
illustrated specimen of J. globosa (Fig. 5E) is very similar to 
J. janthina in anatomy, although its head is extended rather 
than the snout; the forked cephalic tentacles are visible near 
the mouth. The large Lepas barnacles attached to the shell hide 
the area where an epipodium would have been expected. The 
specimen of J. umhilicata (Fig. 5C) is included to show its 
very long, narrow float closely resembling that of J. exigua 
(Laursen, 1953: fig. 1). These two species are closely similar 
in ah characters other than the prominence and spacing of 
their exterior collabral sculpture. Several of these photographs 
(Figs 4B-C, 5A, E) reveal that the only obvious function of 
the sinus in the outer lip of the shell is to allow the head and 
snout to be maintained outside the anterior end of the shell, 
resting in the lip sinus. The lack of such a sinus in Reduzia 
species is shown in Figs 6-7 to result from the head and snout 
of Reduzia species being relatively smaller than in Janthina 
species, and not resting on the lip of the shell as they do in 
Janthina species. 
Reproduction and larvae. Robertson (1981b) demonstrated 
protandrous hermaphroditism in an Epitonium species, and this 
is shared with many other epitoniids (Collin, 2000). Graham 
(1954) also reported that ah male specimens he observed 
of Janthina janthina were markedly smaller than female 
specimens. Ankel (1930) reported the same size relationship 
in another species, probably J. pallida. However, Laursen 
(1953: 9-11) reported specimens in male, sterile and female 
phases, usually in increasing size order, although “the male and 
female individuals of presumably the same spat-falls are of the 
same size. Furthermore, there are in the material [examined by 
Laursen] sterile individuals, i.e. individuals which are neither 
in a male nor a female phase, and individuals which are both 
male and female” (Laursen, 1953: 9). Laursen (1953: fig. 2) 
illustrated the animal of a specimen of J. pallida with both male 
and female organs functioning simultaneously. A functional 
seminal duct is located on the wall of the mantle cavity, and 
a swollen oviduct full of eggs is attached to the same wall 
above the seminal duct. However, Laursen (1953: 11) also 
noted that in the majority of large specimens he dissected the 
seminal duct had disappeared and the oviduct, closely packed 
with eggs, occupied almost the entire body cavity. Wilson & 
Wilson (1956: 302) kept two large specimens of J. janthina 
from southern England alive in an aquarium, both “about 
the maximum size we saw”. They reported that one shed 
packets of veligers whereas the other shed spermatozeugmata, 
indicating that large specimens can be either male or female. 
This is countered, however, by the observations on egg 
capsule occurrence by Okano & Wada (2012). They measured 
specimens in a mass stranding of J. globosa (Swainson, 
1822) on the Sea of Japan coast, illustrating current and 
depleted capsules attached to some of the same floats, and 
determined that capsules were laid by ah 41 specimens larger 
than 27.4 mm high in a collection of about 170 specimens 
(24%) ranging in height from 6.08-40.36 mm; i.e., ah large 
specimens of J. globosa were female. It seems likely that a 
single cycle of protandry is normal in Janthina species, but is 
