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Bloodworms at the beach

The Scripps Coastal Reserve (SCR) includes a wide expanse of sandy beach. Although the surface of any beach is largely devoid of organisms there is a rich community of invertebrates hidden in the sand, mostly worms, molluscs, and crustacea. These animals provide important ecosystem services as they recycle nutrients and are the main prey for many species of shore birds.

At the SCR the most abundant animal is a polychaete worm, commonly called a bloodworm because of its knock-your-socks-off bright red color (due to hemoglobin). We have seen hundreds of individuals in a single 10 cm diameter core of sand. Despite their abundance, however, no one knew haw many species there were until recently. Recent research in the Rouse lab at SIO suggests that three species in the genus Thorocophelia exist at a beach in northern California, with each species more common in a different zone of the intertidal (Law, Dugan, and Rouse, 2013). At SCR, there did seem to be size differences in the upper and lower parts of the beach. In spring 2012 UCSD students tested the hypothesis that there are multiple species of bloodworm at the SCR. Ecology students collected from different parts of the intertidal. Molecular biology students extracted DNA, generated barcode data, and did a BLAST search. Our results showed that all of the bloodworms at the SCR belong to one species, Thorocophelia mucronata. We hypothesize that size difference are due to age or the quality of the habitat.

  • Law, C.J, K.M. Dorgan, and G.W. Rouse. 2013. Validation of three sympatric Thorocophelia species (Annelida: Opheliidae) from Dillon Beach, California using mitochondrial and nuclear DNA sequence data. Zootaxa 3608: 67-74.