Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 August 2023 | 15(8): 23819–23821
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.8309.15.8.23819-23821
#8309 | Received 07
December 2022 | Final received 14 August 2023 | Finally accepted 18 August 2023
A novel anti-predatory mechanism
in Indrella ampulla (Gastropoda: Ariophantidae)
Karunakar Majhi 1, Maitreya Sil 2 &
Aniruddha Datta-Roy 3
1,2,3 National Institute of Science
Education and Research (NISER), P.O. Jatni, Dist. Khurda, Odisha 752050, India.
1 karunakar.majhi@niser.ac.in
(corresponding author), 2 maitreya.sil@niser.ac.in, 3 datta.roy@niser.ac.in
Editor: Basudev Tripathy, Zoological Survey of India, Pune, India. Date of publication: 26
August 2023 (online & print)
Citation: Majhi, K., M. Sil & A. Datta-Roy (2023). A novel
anti-predatory mechanism in Indrella
ampulla (Gastropoda: Ariophantidae). Journal of Threatened Taxa 15(8):
23819–23821. https://doi.org/10.11609/jott.8309.15.8.23819-23821
Copyright: © Majhi et al. 2023. Creative Commons Attribution 4.0 International
License. JoTT
allows unrestricted use, reproduction, and distribution of this article in any
medium by providing adequate credit to the author(s) and the source of
publication.
Funding: Internal funding from National Institute of Science Education and Research (NISER)
under the Department of Atomic Energy (DAE), Govt. of India.
Competing interests: The authors declare no competing interests.
Acknowledgements: We would like to acknowledge R
Chaitanya, Prof. Praveen Karanth,
David Raju and the entire team of Wayanad wild - CGH Earth for assisting us in
the field work and providing valuable insights on this note. Lastly, we would
like to thank the School of Biological Sciences, National Institute of Science Education
and Research, Bhubaneswar, Odisha, India, for the departmental and logistical
support.
Indrella ampulla (Benson, 1850) is a large-bodied
terrestrial air-breathing gastropod mollusc belonging
to the family Ariophantidae. It is endemic to the
Western Ghats of peninsular India (Benson 1850; Blandford and Godwin-Austen 1908).
Indrella is a monotypic genus comprising of
polymorphic variants spatially separated across the Western Ghats. It is
generally found in the wet evergreen forests and different plantations areas of
the central and southern Western Ghats (Narayanan & Aravind 2021).
In this note we report the
smearing behaviour as a novel anti-predatory strategy
followed by these large gastropods as an extension of the frothing behaviour reported earlier. Three individuals of Indrella ampulla (two yellow morphs and one
orange morph) were observed after agitating them by hand on 25 June 2022 at
12:44 h and 14 July 2022 at 15:41 h. All three individuals were fairly
aggressive in terms of their defence mechanism by
producing froth along with a slimy secretion to cover their shell. The
observations were made in Wayanad in the state of Kerala (11.5144°N and
76.0389°E, 838 m) and in Coorg in the state of Karnataka (12.2283°N and
75.6542°E, 1,088 m) in India. All the observations were made on private
properties.
The observations were made while
assessing the microhabitat preference of land snails in the Western Ghats. Two
of the individuals (yellow morph of Indrella
ampulla) were agitated by hand in Lakkidi to
observe their behaviour when subjected to stress;
these individuals were found on different substrates – one on a rock and the
other on a tree trunk. We observed that both individuals secreted foam that was
viscous and sticky in nature. Upon detection of physical stress, the
individuals stopped their movement and started smearing their slime on their
shell with the tail end of their body until the potential threat was over (Figure
1; see Video 1). Such response was only
observed upon overstimulating the animal. The source of the secreted foam was
observed to be the surface of the mantle mucus cells (Rollo & Wellington 1979)
(Image 1; Video 2). A similar behaviour
was also observed in case of the orange individual in Coorg. The agitation
experiments were performed by KM in all three cases.
Frothing behaviour
was earlier reported as a defence mechanism in the
red morph of Indrella ampulla during an
observation of a cane turtle feeding on one of the individuals (Deepak &
Vasudevan 2009). Here for the first time, we observed similar occurrences in
the yellow and the orange morph as well. Foaming as an anti-predatory strategy
was also reported earlier in several other species of terrestrial gastropods
such as Helix pomatia (Pollard, 1975), which
when attacked produced a copious amount of froth. Exudation of slime is also
studied in many slugs such as Arion fasciatus
and Deroceras reticulatum,
the sticky slime makes slugs a difficult prey (Pakarinen
1994; Mair & Port 2002). Certain other species of
terrestrial snails such as Karaftohelix editha and Karaftohelix gainesi swing their shells in order to get
rid of the predators (Morii et al. 2016). Ovachlamys fulgens,
also known as the jumping snail, propels (jump) its body when disturbed
(Teixeira et al. 2017). Cantareus apertus rocks its shell back and forth to produce sound
(Wenger 2014).
In case of Indrella
ampulla, smearing the slime over the shell with the tail also serves as a defence mechanism, potentially covering the animal
completely with slime to deter predators. It is a large-bodied semi-slug
like animal which requires an effective strategy to avoid predation since it
cannot retract its entire body into the shell to protect itself. Similar
observation and assessing the nature of the secretion and the trait governing it
may also provide important insights to the mechanisms of defence.
For
figure & image – click here for full PDF
Video 1. An
Individual of Indrella ampulla
spreading its slime on its shell. © Karunakar Majhi.
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