Singapore Wild Animals: October 2012

Annelids

Phylum Annelida

Annelids are a phylum of segmented worms. Well known members of this phylum are the earthworms and leeches. The classification of this phylum and related phyla needs further research.

19 species of earthworms are found in Singapore.¹

Earthworms at Punggol Waterway Park ©Tan KH

Earthworm attacked by ants at Woodlands ©Tan KH

Less well known members of this phylum are the polychaete worms (Class Polychaeta)^2,3, which include the tubeworms. Tubeworms are common in the mudflats of Chek Jawa. They are so called because they build a breathing tube out of their underground burrow. Two main types can be easily distinguished. The one with the leaves or debris stuck to the breathing tube are the Diopatra, while the one without can be any of a wide range of polychaetes.

Moonshell egg case with 2 types of tubeworms at Chek Jawa ©Tan KH

References

1. Terrestrial earthworms (Oligochaeta) from Singapore
2. Checklist of polychaete species from Singapore waters (Annelida)
3. A Guide to Seashore Life by Dr Leo W H Tan and Peter K L Ng

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

Atopos sp. at Neo Tiew Lane 2. Yellow-shelled semi-slug Parmarion sp. at Dairy Farm ©Tan KH

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

Tropical Leatherleaf Laevicaulis alte (left) and Parmarion (right) at Neo Tiew Lane 2 ©Tan KH

Blinking Snail Quantula striata at Neo Tiew Lane 2 and Woodlands ©Tan KH

Unknown slug at Neo Tiew Lane 2 ©Tan KH

References

1. The invasive Caribbean bivalve Mytilopsis sallei (Dreissenidae) introduced to Singapore and Johor Bahru, Malaysia
2. A Preliminary Checklist of the Molluscs of Singapore

Flatworms

Phylum Platyhelminthes

This phylum includes all the colourful land planarian worms, parasitic tapeworms, flukes and other flatworms.

Land Planarian Worm (Bipalium sp.) at Rifle Range ©Eddy Lee

Land Planarian Worm (Bipalium sp.) at Neo Tiew Lane 2 ©Tan KH

Tapeworm at Sungei Buloh ©Danny Lau

Invasive New Guinea Flatworm (Platydemus manokwari) ©Lau SY

Reference:
New Guinea flatworm Platydemus manokwari in Singapore

Crabs

Singapore Crabs

True Crabs (Brachyurans)

Small crabs at Sungei Buloh ©Tan KH

Superfamily Dromioidea

Family Dromiidae (Burrowing Crabs)

Superfamily Calappoidea

Family Calappidae (Box Crabs)
Family Matutidae (Moon Crabs)

Superfamily Carpilioidea

Family Carpiliidae

Superfamily Corystoidea

Family Corystidae (Masked Burrowing Crabs)

Superfamily Dorippoidea

Family Dorippidae (Sponge Crabs)

Superfamily Eriphioidea

Family Menippidae (Stone Crab)
Family Oziidae (Forceps Crab)
Family Eriphiidae

Spotted-belly Forceps Crab (Ozius guttatus) at Chek Jawa ©Tan KH

Superfamily Leucosioidea

Family Leucosiidae (Pebble Crabs)

Superfamily Majoidea (Spider Crabs)

Family Majidae
Family Epialtidae
Family Inachidae (Velcro Crab, etc)

Superfamily Parthenopoidea

Family Parthenopidae (Elbow Crabs)

Superfamily Pilumnoidea

Family Pilumnidae (Hairy Crabs)

Superfamily Portunoidea

Family Portunidae (Swimming Crabs, Flower Crabs, Mud Crabs)

Flower Crabs (Portunus pelagicus) are one of the crabs commonly sold in marketplaces. They have a distinctive "flowery" pattern on their shell. They are a type of Swimming Crab (Family Portunidae), which also includes the Mud Crabs used for chilli and pepper crab.

Moulted shell at Chek Jawa ©Tan KH

Mud Crabs (genus Scylla) are the type of crabs found on our dining table. Fortunately, the local mud crabs are not as large as the Giant mud crab (S. serrata), which is the one commonly used for chilli and pepper crabs. They belong to the family Portunidae (the swimming crabs). Singapore has three species: Orange (S. olivacea), Green (S. paramamosain) and Purple Mud Crab (S. traquebarica). The Orange Mud Crab has orange claws, the Green Mud Crab has green and orange claws, and the Purple Mud Crab has purple claws.

Green Mud Crab ©Tan GC. Purple Mud Crab at Chek Jawa ©Tan KH

Orange Mud Crab at Sungei Buloh ©Tan KH

Superfamily Xanthoidea

Family Xanthidae

Superfamily Grapsoidea

Family Grapsidae

Metopograpsus sp. on Coney Island ©Tan KH

Family Plagusiidae
Family Sesarmidae (Sesarmine Crabs, Vinegar Crabs, etc)

Family Sesarmidae includes the tree-climbing crabs, which are commonly seen at Sungei Buloh.

Chek Jawa ©Sylvia Chua. Lorong Halus ©Lau SY

The most easily recognised are the large Vinegar Crabs (Episesarma sp.). The Violet Vinegar Crab (E. versicolor) has pale or violet claws. The Singapore Vinegar Crab (E. singaporense) and Pink-fingered Vinegar Crab (E. chentongense) both have red claws, but the granules on the claws are white in the former and red in the latter. The Pink-and-white-fingered Vinegar Crab (E. palawanense) has a pale dactyl (movable claw) and a red propus (unmovable claw). The Thai Vinegar Crab (E. mederi) has a violet dactyl and a red propus.

Singapore Vinegar Crab (E. singaporense) or Pink-fingered Vinegar Crab (E. chentongense)

Pink-and-white-fingered Vinegar Crab (E. palawanense)

Violet Vinegar Crab (E. versicolor)

Family Varunidae (Paddler Crabs, etc)

Superfamily Ocypodoidea (Stalk-eyed Crabs)

Family Camptandriidae
Family Dotillidae (Soldier Crabs, Sand Bubbler Crabs, etc)

Family Macrophthalmidae (Sentinel Crabs, etc)
Family Ocypodidae (Ghost Crabs and Fiddler Crabs)

Ghost Crabs (Genus Ocypode) belong to the same family (Family Ocypodidae) as the Fiddler Crabs (Genus Uca). They are so called because they are able to disappear quickly into their burrow when threatened. They are found on sandy coasts. Sometimes, they have one claw larger than the other, but the size difference is not as distinct as the fiddler crabs'. There are two species in Singapore - Horn-eyed Ghost Crabs (O. ceratophthalma) and Common Ghost Crab (O. cordimana).

Fiddler Crabs (Genus Uca) belong to the same family (Family Ocypodidae) as the Ghost Crabs (Genus Ocypode). The male is easily recognised by having a claw disproportionately larger than the other. The female has claws of the same size.

Porcelain Fiddler (U. annulipes)
U. dussumieri (probable)
U. forcipata
U. hesperiae (probable)
Rosy Fiddler (U. rosea)
Purple Fiddler (U. paradussumieri)
U. perplexa (probable)
U. rhizophorae
U. tetragonon (probable)
U. triangularis (probable)
Orange Fiddler (U. vocans)