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Phylum Mollusca > Class Gastropoda > sea slugs > Order Cephalaspidea
Headshield snails and slugs
Order Cephalaspidea
updated Oct 2016
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.
 

Order Cephalaspidea recorded for Singapore
from Tan Siong Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist of The Molluscs of Singapore.
^from WORMS

  Family Acteonidae
  Acteon kirai=^Punctacteon kirai

Pupa nitidula
Pupa solidula
Pupa sulcata

  Family Aglajidae (tailed-slugs) with list of species recorded for Singapore.

  Family Bullidae
  Bulla ampulla

  Family Cylichnidae
  Acteocina capitata
Acteocina singaporensis

Cylichna bizona=^Mnestia bizona
Cylichna cylindracea

  Family Haminoeidae (bubble-shell snails) with list of species recorded for Singapore

  Family Hydatinidae=^Aplustridae (paper bubble snails) with list of species recorded for Singapore

  Family Philinidae
  Philine orientalis ('Attap chee' slug)

  Family Retusidae
  Pyrunculus sp.

Retusa pelly

  ^Family Rhizoridae
  Volvulella acuminata

  Family Ringiculidae
  Ringicula acuta
Ringicula folini
Ringicula grandinosa
Ringicula propinquans

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.
  • Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore. National Council on the Environment. 163pp.
  • 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 Hawaii exclusive of the vertebrates Sea Challengers. 314pp.
  • Kuiter, Rudie H and Helmut Debelius. 2009. World Atlas of Marine Fauna. IKAN-Unterwasserachiv. 723pp.
  • Coleman, Neville. 2008. Nudibranchs Encyclopedia - Catalogue of Asia/Indo Pacific sea slugs. Neville Coleman's World of Water, Australia. 415pp.
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