Spaghetti worm (Eupolymnia crasscornis)
By Julian Lim
Dr. James B. Wood Editor
have a distinctive external anatomy that sets them apart from most
other polychaete families. One of their unusual features is that their
prostomium is represented by many extensile buccal tentacles (“palps”).
These tentacles are external to the organism’s burrow, and are used
primarily for food gathering. (Dales, 1955) They can grow to over a
meter in length in some terebellids (Ruppert et al., 2004) and usually
cannot be fully retracted into any coelomic space. Terebellids have an
inner and outer pair of lips below their mouths and a solitary lip
above. The ventral part of the anterior segment of their body possesses
well-developed mucous glands, and they have three pairs of branched
Internally, terebellids have a well-developed gut consisting of an oesophagus, fore-stomach, hind-stomach and intestine, and use enzymatic activity to carry out digestion. Like other polychaetes, they have closed circulatory systems with no specialized heart
rate is positively correlated with temperature ranging from 10°C
(50°F) to 20°C (68°F) in Eupolymnia nebulosa; this
is a good explanation as to why spawning in these species occurs during
the warmer months. Temperatures outside this range are not as conducive
for reproduction (Bhaud, 1988). Juvenile growth rate is also, as one
might expect, correlated with food availability. There is thus a
selection for smaller juveniles that will not engage in intra-species
competition when developing in the same area. Juvenile mortality for
species reared in captivity is low. In the wild, E. nebulosa
does not typically migrate very far during early development, this it
is important that larger individuals do not grow at the expense of
their smaller, genetically related counterparts. (Bhaud, 1988).
Terebellids as a
family are gonochoric, and generally have lecithotropic larvae (i.e.
larvae that are short-lived and survive by consuming yolk) that are
externally fertilized (McHugh, 1993). Specific data for the
reproduction of Eupolymnia crassicornis are not available.
Smith (1989) undertook an observational study of terebellid reproductive behavior in the laboratory, finding that egg production occurs exclusively at night, and follows an approximate lunar periodicity. Males do not necessarily wait for the presence of a female to emit sperm and females were observed to release eggs without males in the vicinity. It is not known (or discussed) whether this behavior is maladaptive, serves some unknown function, or was due to the unnatural laboratory conditions. However, all sperm and eggs were released in a 2-week window, following which both males and females abruptly terminated the ejection of gametes.
performed through peristaltic contractions within the burrow (Ruppert
et al., 2003). They are rapid and ‘purposeful’ in the case of Eupolymnia
nebulosa (Smith, 1989).
Slattery (2002) conducted an experiment on E. crassicornis in
Belize to test for the presence of deterrent chemicals in the species.
Bluehead wrasses and green clinging crabs both refused offerings of
tentacles from the worm as well as food pellets treated with worm
extract. This result was significant when compared to controls. The
authors subscribe to the theory that the extracts are produced by the
polychaetes as defense against predation, although a number of other
possibilities were also mentioned. For example, Pawlik (1992) reported
that Thelepus crispus, a terebellid residing in U.S. Pacific
waters, uses brominated-aromatic metabolites to protect the area around
its burrow from settling larvae. This strongly discourages competitors
from establishing themselves in a perimeter around the polychaete, thus
decreasing competition with the animal for nutrients. Other potential
functions of terebellid secondary metabolites are reviewed in an
article by Hay (1996).
Indeed, it is not always a certainty that metabolites produced by invertebrates are used for defense. Kicklighter et al. (2003) asserts that ecological function cannot be ascertained by metabolite chemical structure alone; many compounds assayed from invertebrates have little or no icthyodeterrent properties. Neither group of researchers was able to identify the active metabolite in Eupolymnia crassicornis.
Ecologically, the palatability of an organism was correlated with its vulnerability in the wild. Further research by Kicklighter et al. (2003) showed that the body of Eupolymnia crassicornis is palatable to fish (although they concurred with the finding that its tentacles are poisonous). Protected by its tube, it is not surprising that the epibenthic E. crassicornis should lack deterrent chemicals in its main frame.
It has been suggested that this chemical defense in Eupolymnia tentacles not only reduces predation but also enables the organism to forage over a wider area of sediment given that these are the only areas it has exposed during this time (Kicklighter et al., 2003). Interesting related studies have failed to find chemical deterrents in other members of this organism’s taxonomic group (e.g. Eupolymnia nebulosa (Goerke and Weber, 1991)) indicating that the feature is not a synapomorphy of the genus Eupolymnia. The authors suggest that evolution of the trait in E. crassicornis is a function of its tropical habitat, given that predation is a more significant problem for organisms in warmer climes.
(1988) investigated the tube-building and feeding activity in Eupolymnia
nebulosa. These two activities are antagonistic – that is, the
amount of time spent on one directly impacts the amount spent on the
other, since both employ the same body parts. It was found that E.
nebulosa demonstrated size selectivity in which particles they used
for what purpose: smaller particles were preferentially selected by the
organism to be ingested (for the epiphytes residing on them), and
larger particles were typically used to build its tube. This strategy
is presumably employed to maximize energy efficiency. Terebellid
tentacles do not have very strong adhesive properties, thus the
positive selection for more manageable particles for transportation to
As of this writing, this species is not commercially important.
There are no Bermudan laws governing this species
The casing of one of these worms was one of the more remarkable things we found during the causeway field trip (Annelid lab, MIZ week 3) . There was, unfortunately, no live specimen inside it. The tube was approximately 12 cm in length and was constructed of broken gastropod shells, gravel and other detritus. It was found at a depth of about half a meter (during low tide) in an intertidal sandy area.
Browsing through the recent research done on genus Eupolymnia, what was most striking to me was the uniqueness of the defense strategies of the Bermudan species. Producing noxious or lethal chemicals can be energetically expensive and divert resources away from an organism’s other functions. Given that E. crassicornis already has significant structural defenses (by way of its tube building), it is perhaps a little surprising that it should produce allelopathic substances as well. Moreover, the explanation (above) of the evolution of this trait by Kicklighter et al. (2003) is definitely inadequate, as specimens of E. nebulosa are readily found in Bahaman and other tropical waters. Further work needs to be done to elucidate the selective pressures for the development of chemical defense in E. crassicornis.
Furthermore, the chemistry of the deterrents in E. crassicornis has not yet been discovered; extracts of these substances degrade very quickly and have not been successfully analyzed. It would be interesting to know if the substances produced by the spaghetti worm have any secondary importance for the organism or commercial relevance to society.
Bhaud, M. (1988). Influence of temperature and food supply on development of Eupolymnia nebulosa (Montagu, 1818) (Polychatea: Terebellidae). J. Exp. Mar. Biol. Ecol. 118:103-113.
Dales, R.P. (1955). Feeding and digestion in Terebellids. J. Mar. Biol. Ass. U.K. 34: 55-79.
Gaston, G.R. and Slattery, M. (2002). Ecological fuinction of chemical deterrents in a tropical polychaete, Eupolymnia crassicornis (Annelida, Terebellidae), in Belize. Bulletin of Marine Science 70(3): 891-897.
Goerke, H. and Weber, K. (1991). Bromophenols in Lanice conchilega (Polychaeta, Terebellidae): the influence of sex, weight and season. Bulletin of Marine Science. 48: 517-523.
Grémare, A. (1988). Feeding, tube-building and particle-size selection in the terebellid polychaete Eupolmnia nebulosa. Marine Biology 97(2): 243-252.
Hay, M.E. (1996) Marine chemical ecology: what’s known and what’s next. J. Exp. Mar. Biol. Ecol. 200: 103-104.
Kicklighter, C.E., Kubanek, J., Barsby, T. and Hay, M.E. (2003). Palatability and defense of some infaunal worms: alkylpyrrole sulfamates as deterrents to fish feeding. Mar. Ecol. Prog. Ser. 263: 299-306.
McHugh, D. (1993). A comparative study of reproduction and development in the Polychaete family Terebellidae. Biol. Bulletin Mar. Biol. 185(2):153-167
Pawlik, J.R. (1992). Chemical ecology of the settlement of benthic marine invertebrates. Oceanogr. Mar. Biol. Ann. Rev. 30: 273-335.
Ruppert, E.E., Fox, R.S., Barnes, R.D. (2003). Invertebrate zoology: A functional evolutionary approach. 7th ed. Brooks/Cole – Thomson Learning, CA.
Smith, R.I. (1989). Observations on spawning behavior of Eupolymnia nebulosa and comparisons with Lanice conchilega (Annelida, Polychaeta, Terbellidae). Bulletin of Marine Science. 45(2): 406-414.
Sterrer, W. (1986) Marine Fauna and Flora of Bermuda: A Systematic Guide to the Identification of Marine Organisms. Wiley-Interscience, U.S.A.
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