Singapore Wild Animals: Molluscs

Phylum Mollusca

The members of this phylum are typically called shellfish, but this phylum also includes the octopus, squids, cuttlefish, snails and slugs. Moreover, lobsters, crabs and shrimps are not molluscs, although they are sometimes also called shellfish. Generally, those with 2 external shells are called bivalves (Class Bivalves); those with a single external shell is called a gastropod (Class Gastropoda) and those without an external shell are called cephalopods (Class Cephalopoda). However, things are more complicated than that. E.g., gastropods which lack an external shell, like the slugs, as well as chitons which have a single shell, but are not gastropods.

There are more than 1200 species of molluscs in Singapore¹.

Class Bivalvia

Bivalves are so called because they have two shells enclosing the soft body. Typical members of this class are oysters, mussels, clams, cockles, etc.

Rock Oyster (Family Ostreidae) at Chek Jawa ©Tan KH: Stuck to rock. With Asian Green Mussels

Asian Green Mussels Perna viridis: Sungei Buloh ©Lau SY. Chek Jawa ©Tan KH

The invasive² Mytilopsis sallei at Sungei Serangoon ©Tan KH

Class Gastropoda

Gastropods has a single shell enclosing the soft body. Typical members of this class are snails, slugs, nudibranchs (sea slugs), etc.

Noble Volute Cymbiola nobilis at Changi ©Tan KH

Telescopium telescopium at Sungei Buloh ©Tan KH

Sungei Buloh. Lined Nerite Nerita articulata ©Tan KH. Lined Nerite with Black Chut-chut Cerithidea quadrata ©Lau SY

Sand collar (egg case) of Moonshell or Moon Snail (Family Naticidae) at Chek Jawa ©Tan KH

The introduced Giant African Snail Achatina fulica mating at Neo Tiew Lane 2, and a garden snail Subulina octona at Mattar Road ©Lau SY

Common Big-jawed Spider with eggs of introduced apple snail Pomacea sp. at Springleaf. Young Mayan Cichlid with apple snail at Jurong Lake ©Tan KH