bivalves text index | photo index
Phylum Mollusca > Class Bivalvia > Family Mytilidae
Horse mussel
Modiolus sp.
Family Mytilidae
updated May 2020
Where seen? This large angular brown mussel is usually only sometimes seen in small numbers in seagrass meadows. In 2019, however, they formed dense patches on large areas on Changi Beach. They were also seen in large clusters on Pulau Semakau South in 2020.

Features: 3-4cm long. The two-part shell is shiny brown, thin, fragile and smooth. The shell is rather triangular, the older part of the shell seems to have hairs. It lies on the ground, sometimes partially buried, and produces byssus threads to anchor to the ground. Usually among seagrasses.

What eats them: On Cyrene in 2020, small clusters of the mussel were seen. They were mostly dead (empty shells) and Reef murex snails appeared to be feeding on them.

Status and threats: According to Tan Koh Siang, in the 1970s, Modiolus metcalfi used to be common in sandy and muddy areas in the intertidal and subtidal estuarine areas such as Lim Chu Kang. They are rarely seen nowadays.

Pulau Sekudu, Jul 13

Pulau Sekudu, Jul 13

Dense carpet on the shore
Changi, Feb 19

Horse mussels on Singapore shores
On wildsingapore flickr

Horse mussels (Modiolus sp.)



  • 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.
  • Tan, K. S. & L. M. Chou, 2000. A Guide to the Common Seashells of Singapore. Singapore Science Centre. 160 pp.
links | references | about | email Ria
Spot errors? Have a question? Want to share your sightings? email Ria I'll be glad to hear from you!
wildfactsheets website©ria tan 2008