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Loimia medusa (Savigny in Lamarck, 1818) 

Spaghetti-Worm or the Red-Spotted Worm


John McLaughlin (2014)

 


Fact Sheet

Minimize

Summary


Brief Summary


Classification


Names


Physical Description


General Body Plan


The Tentacles


Colouration


Ecology


Habitats


Crypsis


Larvae


Behaviour


Overview


Feeding


Predatory Defense Mechanisms


Survival Mechanisms


Reproduction


Reproductive Characteristics


Reproductive Strategy


Case Study


Ecological Role


Overview


Secondary Production


Sediment Processing


Biogeographic Distribution


Life History


Larval Development


Building of Sandy Tube


Early Benthic Development


Conservation and Threats


References & Links

Predatory Defense Mechanisms



With regard to protecting the sensitive tentacles which are constantly at risk of predation in the pen water column, Loimia medusa has developed specific survival strategies. Each of the tentacles can be individually controlled and quickly retracted at any sight of disturbance. If, for any reason, one or several of the tentacles are broken off or eaten by predators, they will regenerate at only minor cost to the organism. In fact for organisms such as the blue-stripe butterfly fish spaghetti worm tentacles make up a large proportion of their diet (Waikiki Aquarium, 2013).



source:http://www.dafni.com/vermes/TN_Loimia%20medusa1.JPG


L. medusa spends a majority of its adult life safely hidden away within the tubes or burrows that they themselves construct. However, specific mass swarming events of this basically sessile polychaete within the free water column after disturbance events has been described as a behavioural flight reaction (W. Westheide, 2003). Within this reaction individuals of this species have been documented to demonstrate locomotory abilities rarely seen in this family of terrebelids, a behavioural and morphological adaption that aids in increasing the defensive capabilities of the species but also the dispersal and increased reproductive success of the organism. In response to natural observations, laboratory experiments were undertaken in which these animals were seen to swim through the vigorous movement of their bodies, or simply sank to the bottom of their enclosures. Regardless, in response to the absence of shelter or feeding material within the enclosures, resting animals once again began to move. Initially the individuals swim upward at an oblique angle, more or less vertically, before continually bumping against the water’s surface (W. Westheide, 2003). In the process of this movement the animal’s tentacles were retracted and left to hang down in two distinct groups. One on the right side of the anterior pole of the body and the other on the left, parallel to each other. In the act of retraction, the tentacles of L. medusa are seen to reduce to about a third of their initial size when the animal was resting. The locomotary swimming action itself was a result of continuous jerking contractions in timing with whole body twisting motions at such a pace that no regular pattern is attainable with the naked eye (W. Westheide, 2003). 
Throughout swimming the trunk of the animal does not move laterally nor does it move ventrally, but rather undergoes a complex three-dimensional, even helical movement that could more or less be described as wriggling. In fact this ‘wriggling’ motion has been observed in some individuals to endure for in excess of 30mins, and L. medusa could presumably maintain this behaviour in open water for hours without rest, in turn keeping their bodies below the water’s surface yet suspended within the water column (W. Westheide, 2003). 
Such behaviour would be particularly beneficial as a defence mechanism against this species numerous predators, i.e. cone shells, in which they could flee large distances into the water column before settling once again. In addition such behaviours are useful in increasing survival by giving these individuals the ability to leave specific micro-habitats in search of new shelter, food or entirely new ecosystems, a great dispersal method for a species which lives most of its life as a sessile organism. 


Classification

Minimize
Kingdom
Animalia
Phylum
Annelida
Class
Polychaeta
Order
Terebellida
Family
Terebellidae
Genus
Loimia

Synonyms

Terebella medusa (Savigny, 1822)

Common Names

medusa worm
spaghetti worm
Medusenwurm
Spaghetti-Wurm
Kingdom
Animalia
Phylum
Annelida
Class
Polychaeta
Order
Terebellida
Family
Terebellidae
Genus
Loimia
Species
medusa