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Loimia medusa (Savigny in Lamarck, 1818) 

Spaghetti-Worm or the Red-Spotted Worm

John McLaughlin (2014)


Fact Sheet



Brief Summary



Physical Description

General Body Plan

The Tentacles









Predatory Defense Mechanisms

Survival Mechanisms


Reproductive Characteristics

Reproductive Strategy

Case Study

Ecological Role


Secondary Production

Sediment Processing

Biogeographic Distribution

Life History

Larval Development

Building of Sandy Tube

Early Benthic Development

Conservation and Threats

References & Links

Building of Sandy Tube

At the point of development when the young L. medusa larva are ready to settle down they display an instinctive impulse to build. Naturally sand is the sediment of choice but if unavailable, they may collect hairs, faecal matter and other debris in order to construct tubes, using their tentacles to collect the sediment around them. This sediment is coated over with the exact ‘cement’ which is used to connect individual particles together. At the moment the animal comes to rest on its benthic substrate the larvae reaches forth its tentacles in a comprehensive search of its immediate neighbourhood. As these tentacles make contact with sand grains or other particles they are immediately seized and conveyed toward the mouth. Particles can be dragged toward the mouth, causing them to travel down the deep groove of the animals tentacles which allows L. medusa to convey more than one grain at a time for each tentacle, with several sliding down its groove one after another. All this time the buccal organ is working vigorously, and within just two to three seconds the particle, already coated in ‘cement’, is pushed into the desired position using the head and anterior of the body, the upper lip with a strong hold at all times. As the particle is released another fragment is immediately dealt with in identical fashion. Building in this manor the length of the sandy tube is rapidly constructed away from the mouth of the larval gelatinous case and is attached to whatever the substrate may be. Corresponding to the increased length of the sandy tube the larva gradually discards its transparent case until it is completely absent. Once the individual has constructed a suitable length of tube in a particular direction it will turn around and begin building from the other end. Unlike similar species, L. medusa displays very little selection with regard to the grains used, taking sediments in a range of sizes and composition. Astoundingly it takes just 30mins for a larva to construct a sandy tube about twice its own length, excluding tentacles. During this frantic building stage it is possible for some fragments to be accidently swallowed; however they quickly pass through the gut before being voided out the anus.