Species Description: The orange fringed worm, Cirratulus grandis, is a small benthic polychaete. Like other worms belonging to the phylum Annelida, the orange body of C. grandis is divided into numerous segments. The majority of the worm is usually concealed within a borrow beneath the sediment, while long yellow to whitish feeding tentacles and gills attached to the anterior portion of the body are exposed on the sediment surface (Ruppert & Fox 1988). The feeding tentacles resemble the gills in appearance, except for the presence of a ciliated groove used to transport particles to the mouth (see 'Trophic Mode' below). In addition to the gills near the head, each segment of the body bears fine gill filaments that extend into the surrounding sediment for gas exchange. When disturbed, the worm retracts all exposed tentacles and gills into the burrow for protection.
Regional Occurrence & IRL Distribution: Little information is available concerning the distinct range and distribution of C. grandis. However, the species has been cited as occurring along the east coast of the United States, as far north as New England. In the IRL, the species ranges throughout the lagoon in muddy and sandy sediments.
Age, Size, Lifespan: The orange fringed worm grows to approximately 5 cm in length (Ruppert & Fox 1988). Little information is available concerning the growth rate or lifespan of the species.
Abundance: Abundances for C. grandis in IRL soft sediment habitats are unknown. However, the worms are known to be quite numerous in some locations within their range. One study on populations in Boston Harbor revealed worm densities up to 1,400 m-2 (Shull & Yasuda 2001).
Temperature & Salinity: While little information exists concerning the environmental tolerances of the orange fringed worm, its natural range suggests it prefers temperate to tropical marine and estuarine waters.
Trophic Mode: C. grandis is a selective deposit feeder, consuming organic particles found within the sediments. Extending its long tentacles out of the burrow in all directions, the worm collects particles and transfers them toward the mouth via ciliated grooves on each tentacle (Ruppert & Fox 1988). The organic material is digested and the inedible sediment is excreted at the bottom of the burrow. Studies have found that the orange fringed worm does discriminate when selecting sediments on which to feed, choosing particles ranging from 16 to 32 μm (Shull & Yasuda 2001).
Predators: Although information concerning predators of C. grandis is scarce, the rockworm is likely a prey item of several species of wading birds, larger invertebrates and bottom-feeding fishes.
Ecological Importance: Because of its infaunal lifestyle and deposit-feeding trophic mode, C. grandis is used as a test organism to study the concentrations and effects of various pollutants found within sediments in marine environments (Rust et al. 2004a, 2004b).
Like terrestrial earthworms and many other benthic marine invertebrates, C. grandis also helps to overturn and oxygenate sediment by mixing particles during burrowing and feeding activities (Shull & Yasuda 2001).
Ruppert, EE & RS Fox. 1988. Seashore Animals of the Southeast: A guide to common shallow-water invertebrates of the southeastern Atlantic coast. Univ. South Carolina Press. Columbia, SC. 429 pp.
Rust, AJ, Burgess, RM, Brownawell, BJ & AE McElroy. 2004a. Relationship between metabolism and bioaccumulation of benzo[a]pyrene in benthic invertebrates. Env. Toxic. Chem. 23: 2587-2593.
Rust, AJ, Burgess, RM, McElroy, AE, Cantwell, MG & BJ Brownawell. 2004b. Influence of soot carbon on the bioaccumulation of sediment-bound polycyclic aromatic hydrocarbons by marine benthic invertebrates: an interspecies comparison. Env. Tox. Chem. 23: 2594-2603.
Shull, DH & M Yasuda. 2001. Size-selective downward particle transport by cirratulid polychaetes. J. Mar. Res. 59: 453-473.