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Swift strike by the gastropod Scaphella junonia on its gastropod prey Americoliva sayana

  • Bailey-Matthews National Shell Museum
  • Bailey-Matthews National Shell Museum


The fast attack by Scaphella junonia on Americoliva sayana was filmed in captivity. Volutidae described in the literature first envelop their prey with the foot, ingesting them in the "foot chamber" thus formed. Scaphella junonia first attack prey in open water, then may use foot to move them around. [Published on 2018-08-28 in the "Fast Track" section of the Bulletin of Marine Science online.]
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Swift strike by the gastropod Scaphella junonia on its gastropod
prey Americoliva sayana
ArticleinBulletin of Marine Science -Miami- · August 2018
DOI: 10.5343/bms.2018.0058
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Jose H. Leal
Bailey-Matthews National Shell Museum
Rebecca Mensch
Bailey-Matthews National Shell Museum
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BULLETIN OF MARINE SCIENCE. 00(0):000–000. 0000
Bullen of Marine Science
© 2011 Rosensel School of Marine and Atmospheric Science
of the University of Miami
Bulletin of Marine Science
© 2019 Rosenstiel School of Marine & Atmospheric Science of
the University of Miami Portraits of Marine Science
Bull Mar Sci. 95(1):27–28. 2019
Swift strike by the gastropod Scaphella junonia
on its gastropod prey Americoliva sayana
José H Leal *, Rebecca A Mensch
Bailey-Matthews National Shell Museum, 3075 Sanibel-Captiva Rd, Sanibel, Florida 33957.
* Corresponding author email: <>.
We record for the first time a strike by the volutid Scaphella junonia (Lamarck, 1804)
(“junonia”) on its preferred prey, the lettered olive, Americoliva sayana (Ravenel, 1834), and
the ensuing reaction of the latter to the attack. ree junonias were collected by one of us (RA
Mensch) during the Gulf of Mexico expedition, February 23–26, 2018, of R/V W
II, (GS Herbert, Chief Scientist). e junonias were kept alive in a 208-L tank with a layer of
sand of similar granulometry to the substrate at the collecting site, and fed lettered olives.
e male specimen featured here measures 82 mm and was collected on February 26, 2018,
at Station XXI N, 26°29.414´N–26°28.684´N, 83°29.553´W–83°29.049´W, 55.5–54.6 m depth.
e specimens will be deposited at the GS Herbert West Florida Shelf Collection, School of
Geosciences, University of South Florida.
Mollusk-eating volutids typically envelop their prey within the posterior part of the lon-
gitudinally folded foot, positioning the head in a ventral and posterior direction, into the
“chamber” thus formed to reach the prey (Ponder 1970, Bayer 1971, Vermeij 1978, Morton
1986, Bigatti et al. 2009, 2010). Morton (1986), after observing Melo melo (Lightfoot, 1786)
feeding on gastropods, remarked that “possibly a venom is produced from a pair of accessory
BULLETIN OF MARINE SCIENCE. VOL 00, NO 0. 000028 Bulletin of Marine Science. Vol 95, No 1. 2019
salivary glands and the pleurembolic proboscis everted into the immobilised prey,” but con-
ceded that this would be difficu lt to observe as the proboscis is hidden from view by the folded
foot. Bigatti et al. (2009) studied Adelomelon ancilla (Lightfoot, 1786) feeding on mollusks,
stating that they release secretions from the accessory salivary glands into the “foot chamber”
to induce muscle relaxation in their prey. Bigatti et al. (2010) reported that Odontocymbiola
magellanica (Gmelin, 1791) captures their prey with the metapodial region of the foot, indi-
cating that the foot creates a “closed environment.” Bayer (1971) briefly described a junonia
feeding in captivity. Given choices of different mollusks and “other invertebrates,” the junonia
ate only three species of gastropods, with lettered olive as the favorite. Bayer noted that the
“prey was always held in the same manner. e junonia (...) inserted its head into the pouch
[the “foot chamber”] for a short time, after which the olive no longer showed any indication
of struggle.”
e three junonias kept in captivity for the present study repeatedly perform a modified
“foot chamber” procedure, mostly using the foot chamber to move a captured lettered olive
around, after a strike in the open. is fast, “open-water” strike was observed several times in
the past 6 mo, and was documented in a 42-s video (by RA Mensch) available at https://youtu.
be/jk5xK6DFoDo. e video shows lettered olive approaching junonia from the right-hand
side of the latter. Panels A–D were from the video. On Panel A (21:27 s), junonia has made
contact with the lettered olive, mostly via its right tentacle, and starts to evert its proboscis
(arrow). On Panel B (24:14 s), the proboscis has been quickly extended; its tip (mouth) strikes
the lettered olive. On Panel C (25:05 s), the lettered olive recoils violently following the strike,
suggesting injection of toxin(s), most likely via piercing of the prey tegument by the radula.
Panel D (27:29 s) shows the lettered olive beginning to slide to the bottom, incapable of mov-
ing. ese events last only 06:02 s. Junonia subsequently ate the lettered olive. ese observa-
tions in captivity indicate that (1) unlike what happens with most mollusk-eating volutids,
predatory strikes by junonias can occur outside the “foot chamber,” (2) the strike is swift and
effective, and (3) the quick recoiling reaction of the lettered olive after the strike suggests that
a fast-acting toxin, or more than one toxin, is (are) injected during the strike.
e authors thank GS Herbert, School of Geosciences, University of South Florida, for in-
viting RA Mensch to participate in the Gulf of Mexico Expedition of R/V W II,
funded by the Florida Institute of Oceanography and the School of Geosciences, University of
South Florida. ree anonymous reviewers provided suggestions and recommendations that
improved the quality of the manuscript.
L C
Bayer FM. 1971. New and unusual mollusks collected by R/V J E P and R/V G
in the tropical western Atlantic. Bull Mar Sci. 21:111–236.
Bigatti G, Sanchez-Antelo CJM, Miloslavich P, Penchaszadeh PE. 2009. Feeding behavior of Adelomelon
ancilla (Lightfoot, 1786): A predatory neogastropod (Gastropoda: Volutidae) in Patagonian benthic
communities. Nautilus. 123(3):159–165.
Bigatti G, Sacristán H, Rodríguez MC, Stortz CA. 2010. Diet, prey narcotization and biochemical
composition of salivary glands secretions of the volutid snail Odontocymbiola magellanica. J Mar Biol
Assoc U K. 90(5):959–967.
Morton B. 1986. e diet and prey capture mechanism of Melo melo (Prosobranchia: Volutidae). J Moll
Stud. 52:156–160.
Ponder WF. 1970. e morphology of Alcithoe arabica (Gastropoda: Volutidae). Malacol Rev. 3:127–165.
Vermeij GJ. 1978. Biogeography and Adaptation: Patterns of Marine Life. Cambridge: Harvard University
Date Submitted: 13 August, 2018.
Date Accepted: 24 August, 2018.
Available Online: 28 August, 2018.
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Full-text available
Odontocymbiola magellanica is a neogastropod very common in Patagonian shallow waters. It feeds exclusively on molluscs inhabiting the same benthic community. Field studies showed that prey preferences are live gastropods (54%) and bivalves (46%). When no living prey are available they change their trophic behaviour to carrion or cannibalism. Feeding mechanisms observations showed that prey are not asphyxiated by the snail's foot as suggested before for the Volutidae family; they are narcotized by saliva introduced in a cavity made by the foot where prey are immobilized. Saliva is produced by the salivary (SG) and accessory salivary glands (AG) and has a pH around 10, relaxing prey muscles, which are consumed alive. Secretions from AG and aqueous extracts of SG and AG were mainly composed of proteins and glycoproteins, though SDS-PAGE gels revealed that salivary proteins were richer in higher molecular weight bands. Fractionation of secretions from AG on Bio-Gel P-100 yielded only one peak. SDS-PAGE showed that it consisted of only one band (MW 51.3 kDa). Microanalysis of cations showed a higher concentration of calcium and magnesium in the accessory salivary gland. Hypotheses of function of different glands are given in relation to feeding behaviour and anatomy of O. magellanica.
Adelomelon ancilla, a volutid commonly found in shallow water in northern Patagonia, is a top predator in the benthic communities of this region. This species presents an anemone (Antholoba achates) epibiosis that may protect it from predators. Adelomelon ancilla captures prey by tightly engulfing it with the foot, and ingests them, generally alive, after narcotizing their muscles. A narcotizing substance, produced by the accessory salivary glands, is released through the proboscis into the prey while the latter is tightly enveloped within the foot, allowing for prey narcotization. In this space, water is not abundant and, therefore, the salivary secretion reaches a high concentration, with a pH of around 10. Analysis of prey obtained in situ indicated that A. ancilla mainly consumes bivalves (88.9%), gastropods (9.5%) and, rarely, sea urchins (1.6%). Ingestion of the prey usually occurs while the predator is buried in the substrate, and may last for several hours. The anatomy of the alimentary system and the pH of various organs involved in prey capture and digestion are presented along with a comparison with feeding mechanisms among other species of Volutidae.
Laboratory experiments undertaken with the South China Sea volute, Melo melo, have shown that it is a specialized predator of other continental shelf predatory gastropods, notably Hemifusus tuba (Melongenidae) and Babylonia lutosa (Buccinidae).