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Headshield
snails and slugs
Order Cephalaspidea
updated
Mar 11
Where
seen? These odd snails and slugs seen on some of our shores
with seagrasses and mangroves.
What are headshield slugs? Headshield
slugs belong to Phylum Mollusca and
Class Gastropoda. They belong to
group of sea slugs (Subclass Opistobranchia)
but most have retained shells as adults, although the shell may be
reduced or internal. There are 31 families of headshield slugs.
Features:
Most have shells that are indeed bubble-like; thin and round. While
some have shells large enough to contain the entire animal, in others,
the shell is reduced or internal. All have a well developed headshield,
used to plough beneath the sand. They have no tentacles. Tailed slugs
of the Family Aglajidae have a long, cylindrical body with a pair
of 'wings' (called parapodia) which fold over the centre of the body
as well as a pair of 'tails, one longer than the other. They have
tiny shells which are internal.
What do they eat? Many bubble
shell snails such as Bulla and Haminoea spp. are herbivores,
placidly munching on filamentous algae.
Some tailed slugs are carnivores and eat their prey whole, crushing
them with hard calcareous plates in the gizzard. Their prey include
other slugs, flatworms,
acoel flatworms
and polychaete worms.
Some have well developed structures to track down their prey by following
the prey's mucous trail. Others are herbivores.
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Order
Cephalaspidea recorded for Singapore
from
Tan Siong Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist
of The Molluscs of Singapore.
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Acteocina
capitata
Acteocina singaporensis
Cylichna bizona
Cylichna cylindracea |
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Family
Aglajidae (tailed slugs) |
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Family
Haminoeidae (bubble shell snails) |
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Atys
cylindrica
Atys naucum
Atys tortuosa
Haminoea sp.
(Mangrove bubble shell snail)
Haminoea galba
Haminoea tenera |
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Pyrunculus
species
Retusa pellyi
Volvulella acuminata |
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References
- Tan Siong
Kiat and Henrietta P. M. Woo, 2010 Preliminary
Checklist of The Molluscs of Singapore (pdf), Raffles
Museum of Biodiversity Research, National University of Singapore.
- Debelius,
Helmut, 2001. Nudibranchs
and Sea Snails: Indo-Pacific Field Guide
IKAN-Unterwasserachiv, Frankfurt. 321 pp.
- Wells, Fred
E. and Clayton W. Bryce. 2000. Slugs
of Western Australia: A guide to the species from the Indian to
West Pacific Oceans.
Western Australian Museum. 184 pp.
- Coleman,
Neville. 2008. Nudibranchs
Encyclopedia - Catalogue of Asia/Indo Pacific sea slugs.
Neville Coleman's World of Water, Australia. 415pp.
- Gosliner,
Terrence M., David W. Behrens and Gary C. Williams. 1996. Coral
Reef Animals of the Indo-Pacific: Animal life from Africa to Hawai’I
exclusive of the vertebrates
Sea Challengers. 314pp.
- Wee Y.C.
and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore.
National Council on the Environment. 163pp.
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