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Phylum Mollusca > Class Bivalvia > Family Mytilidae
Nest mussel
Arcuatula senhousia
Family Mytilidae
updated Oct 2016
Where seen? This tiny mussel is sometimes very common on our Northern shores, forming spongy carpets over vast areas of the shore near the low water mark, as well as on large boulders. It was previously called Muscuslita senhousia.

It is described as an opportunistic species characterised by fast growth and unique ability to colonise both hard and soft surfaces. On hard surfaces, it settles among other creatures that live there. On soft surfaces, the little mussels weave their byssal threads into an all-enclosing nest forming dense mats that can hold more than 2,000 individuals in one square metre. These mats rapidly change sandy bottoms into mud flats as they retain silt. Colonies fluctuate widely and unpredictably.

Features: 1-2cm long. The two-part shell is thin, fragile and smooth. These tiny mussels build communal 'nests' out of byssal threads incorporating sediments, bits of broken shells and other debris. Large areas can be covered in such 'nests', pockmarked with little slits, each housing one mussel. These can carpet rocks or soft bottoms. Sometimes, small Green mussels (Perna viridis) are seen growing among the tinier nest mussels.

Sometimes, Drills are seen grouped on a 'nest', possibly eating them? Several times, seagrasses that might be the Hairy spoon seagrass (Halophila decipiens) were seen growing on nest mussel beds.

Sometimes confused with Little black mussels (Xenostrobus sp.) which are also small, but black and while they may also produce a kind of 'nest', this is not as thick and spongy as the mats created by the Nest mussels.

Human uses: These mussels are considered pests where they establish themselves outside their natural range, e.g., in New Zealand and California. They probably arrived as larvae carried in the ballast water of ocean-going ships. In China and Thailand, they are an inexpensive food and also used to feed poultry, shrimp and fish.
 

These tiny mussels can form vast mats.
Chek Jawa, Aug 07


Pulau Sekudu, Jul 07

Mats coating boulders and the ground.
Pulau Sekudu, Dec 07

Changi, Jul 12

With small Green mussels growing among
the tinier nest mussels.

Pasir Ris, Feb 09

Photo shared by Loh Kok Sheng on his blog.

Nest mussels on Singapore shores

Photos of Nest mussels for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map

Links

References

www.flickr.com
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