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The polychaete Capitella capitata. Photo courtesy Hans Hillewaert.

Species Name: Capitella capitata Fabricius, 1780
Common Name: None
Synonymy: Lumbricus capitatus Fabricius, 1780

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Animalia Annelida Polychaeta Capitellida Capitellidae Capitella

    The polychaete species typically referred to as Capitella capitata is actually comprised of a large group of unnamed sibling species with diverse life history and reproductive attributes (Grassle and Grassle 1976, Grassle, 1980, Petraitis 1985). Detailed examination reveals only slight morphological differences between species, even though life history and reproductive modes differ dramatically (Grassle and Grassle 1976).

    Species Description

    Capitella capitata is a small benthic polychaete belonging to Family Capitellidae. The body is flexible, slender, elongated, and usually blood red in color. The conical, shovel-shaped head and reduced parapodia with chetae in both rami are useful diagnostic features. There is a single genital pore between chaetigers eight and nine, surrounded by cross spines in males.

    Potentially Misidentified Species

    Capitella capitata is morphologically similar to a number of infaunal polychaetes, and positive identification to species level is generally beyond the scope of amateur naturalists.


    Regional Occurrence

    Capitella capitata is generally considered to be a cosmopolitan species in coastal marine and estuarine soft sediment systems. Grassle and Grassle (1976) used electrophoretic enzyme analysis to determine that the global population is actually made up of several genetically distinct (and apparently genetically isolated) sibling species whose distributions overlap such that local C. capitata populations actually consist of a number of co-occurring sibling species.

    IRL Distribution

    Capitella capitata occurs throughout the soft sediment communities of the IRL.


    Age, Size, Lifespan

    Capitella capitata is a small polychaete worm. Specimens may reach 10 cm, but more often they are around 2 cm.


    Infaunal polychaetes such as Capitella capitata can be extremely abundant, generally ranging between several hundred and several thousand individuals per square meter. Sears and Mueller (1989) report a peak seasonal numerical abundance of 22,000 individuals/m2 in a Galveston, TX, mixed-species assemblage consisting primarily of C. capitata, Streblospio benedicti, and Scoloplos foliosus. At other times during the study, abundance declined to a low of around 1,330 individuals/m2.


    Male Capitella species I are capable of developing as simultaneous hermaphrodites, and they do so at greater frequency when females are scarce within the population (Petraitis 1985). Hermaphroditism in Capitella has been hypothesized to be an adaptation to conditions of low faunal density. However, since females do not become hermaphroditic and hermaphrodites don't self-fertilize, Petraitis (1985) suggests hermaphroditism in Capitella is an adaptation to reduce mate competition in small local populations.

    Animals reach sexual maturity at about 4 months in temperate waters, and somewhat faster in warmer areas (Warren 1976, Qian and Chia 1994). In the laboratory, animals became mature in 31-48 days at temperatures ranging around 12.6-22°C (Tsutsumi and Kikuchi 1984). Female produces from 100-1,000 eggs.


    Somewhat similar to the polychaete Streblospio benedicti, Capitella capitata exhibits both pelagic and non-pelagic (direct-developing) larval development strategies (Henriksson 1969, Rosenberg 1976).

    Forbes and Calow (2002) indicate that the Type M and Type I sibling C. capitata species are lecithotrophic (briefly planktonic), while the Type S sibling species is direct-developing. Lecithotrophic larvae are brooded during part of their development within the adult burrow tube (Grassle and Grassle 1974)

    Planktonic-developing Capitella capitata transition over several hours to several days through two distinct free-swimming larval stages (trochophore, metatrochophore) before undergoing metamorphosis and settlement to the benthos as a crawling worm (Biggers and Laufer 1996). This process can be accelerated in the laboratory within the span of an hour or less by exposing larvae to methyl farnesoate which has been shown to be stimulatory to early postembryonic larval stages of crustaceans as well (Laufer and Biggers 2001).

    Dubilier (1988) demonstrated that newly hatched Capitella species I could be induced to settle onto organic-enriched sediments in as little as 30 minutes. The addition of sulphide to experimental sediments delayed settlement by several hours as larvae apparently tried to avoid settling into sulphide-rich areas. Presented alone, however, sulphide induced settlement, in keeping with earlier findings by Cuomo (1985) that sulphide is a positive settlement cue associated with areas of nutrient enrishment.

    Hannan (1981) used collection jars to sample water column availability of C. capitata larvae and demonstrated that larval availability does not determine observed benthic settlement patterns. The author suggested that larval substratum choice and environmental hydrodynamic processes must also be considered when predicting or interpreting recruitment patterns.



    Although it is now largely cosmopolitan in its distribution (excluded only from the tropics), Capitella capitata may have originated from cold marine environments. Wu et al. (1988) collected animals at sea water temperatures of -2° that harbored mature oocytes indicating reproductive activity even under these extreme conditions.


    Examination of NOAA NBI collection records indicate Capitella capitata have been collected from Florida waters ranging in salinity from 41.5 ppt to nearly fresh water.

    Dissolved Oxygen

    Capitella capitata exhibits a relatively high tolerance for sediment hypoxia, hydrogen sulphide concentration, and other sediment conditions avoided by many infauna (Henriksson 1969). Forbes and Lopez (1990) experimentally demonstrated that reduced oxygen concentrations (pO2 = 20 mm Hg or less) led to decreased C. capitata growth rates and cessation of burrowing and feeding activity even when an abundance of food was provided. The authors hypothesize that animals rely solely on anaerobic metabolism once this threshold is crossed. Magnum and van Winkle (1973) similarly observed that C. capitata oxygen uptake ceased when pO2 fell to between 0-34 mm Hg. The fact that experimental worms lost body mass under these conditions supports the contention that full aerobic metabolism cannot be sustained at very low ambient oxygen conditions despite a very high affinity of C. capitata hemoglobin for oxygen. The critical pO2 threshold is higher for larger worms.


    Dense Capitella capitata populations are frequently located in areas with greatly elevated organic content, even though eutrophic sediments are often anoxic and highly sulfidic (Tenore 1977, Warren 1977, Tenore and Chesney 1985a, Bridges et al. 1994).

    Concentrations of more than 300 individuals/m2 were found to occur in a self-sustaining population in proximity to a south Australian lead-zinc smelting facility (Ward and Hutchings 1996).


    Trophic Mode

    Capitella capitata is a deposit-feeding detrital consumer (Henriksson 1969, Levin et al. 1996). Individuals feed by everting a papillose sac-like proboscis to gather detrital deposits. Feeding is primarily non-selective, but gut contents usually include significant algal material, suggesting that some selection may occur (Fauchald and Jumars 1979).

    Tenore and Hanson (1980) demonstrated that detrital materials from different sources were of unequal nutritional value to C. capitata, with decay-resistant Spartina detritus being less available than periphyton or macroalgal detritus. Nutritional value of all types of detritus increased with aging, suggesting that microbial enrichment is an important aspect of benthic detrital energetics.


    Capitella capitata thrive in the absence of intraspecific competition as early colonizers to benthic habitat patches that have been disturbed or otherwise defaunated as a result of environmental stress (Grassle and Grassle 1974, McCall 1977).

    While space may at times be a limiting factor, some experimental evidence exists suggesting that dietary resources are generally not limiting in most infaunal estuarine habitats (Wilson 1990, Bridges 1996).


    An array of benthic fish and invertebrate predators rely on infaunal polychaetes as a seasonally variable dietary resource (Marsh and Tenore 1990). Nelson and Capone (1990) experimentally demonstrated that specific predators impact various infaunal polychaete populations differently, depending on predator foraging strategy and prey species-specific distribution depth.


    Capitella capitata is a component of a great many marine soft sediment communities, including vegetated and unvegetated benthic habitats as well as those with elevated nutrient loads or excess levels of other types of pollutants. It resides within mucus-lined burrows within the substratum (Henriksson 1969, Rosenberg 1976, Forbes and Lopez 1990). NOAA NBI ollections have revealed the presence of this species at depths ranging from inertidal to 57 m.

    This polychaete is a prototypical 'r-adapted' species, i.e., an opportunistic species with high growth, reproduction, and mortality rates. As with most such opportunistic species, C. capitata populations often show variable densities, including pronounced seasonal shifts in abundance (McCall 1977). Rapid growth and reproduction during periods of high food availability appear to push localized populations above carrying capacity, resulting in rapid population declines when resources become scarce and the needs of the population cannot be met. (Chesney and Tenore 1985a, b).


    Special Status


    Economic/Ecological Importance

    A large amount of trophic energy is transferred from Capitella capitata and other infaunal detritivores to benthic consumer levels (Marsh and Tenore 1990). Additionally, Capitella capitata is commonly employed as a pollution indicator species in environmental assessment studies (Reish 1957, Henriksson 1969).


    Biggers WJ and H Laufer. 1996. Detection of juvenile hormone-active compounds by larvae of the marine annelid Capitella sp. I. Archives of Insect Biochemistry and Physiology 32:475-484.

    Bridges TS, Levin LA, Cabrera D, and G Plaia. 1994. Effects of sediment amended with sewage, algae, or hydrocarbons on growth and reproduction in two opportunistic polychaetes. Journal of Experimental Marine Biology and Ecology 77:99-119.

    Bridges TS. 1996. Effects of organic additions to sediment, and maternal age and size, on patterns of offspring investment and performance in two opportunistic deposit-feeding polychaetes. Marine Biology 125:345-357.

    Chesney EJ and KR Tenore. 1985a. Oscillations of laboratory populations of the polychaete Capitella capitata (type I): Their cause and implications for natural populations. Marine Ecology Progress Series 20:289-296.

    Chesney EJ and KR Tenore. 1985b. Effects of predation and disturbance on the population growth and dynamics of the polychaete Capitella capitata (type I). Marine Biology 85:77-82.

    Cuomo MC. 1985. Sulphide as a larval settlement cue for Capitella sp I Biogeochemistry. Vol.1(2): pp. 169-181.

    Dublilier N. 1988. Hv2S: A Settlement cue or a toxic substance for Capitella sp. I larvae? Biological Bulletin, Vol. 174(1) pp. 30-38.

    Fauchald K and PA Jumars. 1979. The diet of worms: A study of polychaete feeding guilds. Oceanography and Marine Biology Annual Review 17:193-284.

    Forbes VE and P Calow. 2002. Population growth rate as a basis for ecological risk assessment of toxic chemicals. Philosophical Transactions: Biological Sciences, Vol. 357 (1425), Population Growth Rate: Determining Factors and Role in Population Regulation. pp. 1299-1306.

    Forbes TL and GR Lopez. 1990. The effect of food concentration, body size, and environmental oxygen tension on the growth of the deposit-feeding polychaete, Capitella species 1. Limnology and Oceanography, Vol. 35 (7) pp. 1535-1544.

    Grassle JF and JP Grassle. 1974. Opportunistic life histories and genetic systems in marine benthic polychaetes. Marine Research, 32:253-284.

    Grassle JF and JP Grassle. 1976. Sibling species in the marine pollution indicator Capitella. Science 192: 567-569.

    Grassle JP. 1980. Polychaete sibling species. Pp. 25-32 in Aquatic Oligochaete Biology, RO Brinkhurst and DG Cook, eds. Plenum Press, New York.

    Hannan CA. 1981. Polychaete larval settlement: Correspondence of patterns in suspended jar collectors and in the adjacent natural habitat in Monterey Bay, California. Limnology and Oceanography, Vol. 26(1) pp. 159-171.

    Henriksson R. 1969. Influence of pollution on the bottom fauna of the sound (Oresund). Oikos, Vol. 20(2) pp. 507-523.

    Laufer H and WJ Biggers. 2001. Unifying concepts learned from methyl farnesoate for invertebrate reproduction and post-embryonic development. American Zoologist 41:442-457.

    Levin L, Caswell H, Bridges T, DiBacco C, Cabrera D, and G Plaia. 1996. Demographic responses of estuarine polychaetes to pollutants: Life table response experiments. Ecological Applications, Vol. 6(4) pp. 1295-1313.

    Magnum CP and W van Winkle. 1973. Response of aquatic invertebrates to declining oxygen conditions. American Zoologist 13:529-541.

    McCall PL. 1977. Community patterns and adaptive strategies of the infaunal benthos of Long Island Sound. Marine Research 35:221-266.

    Nelson WG and MA Capone. 1990. Experimental studies of predation on polychaetes associated with seagrass beds. Estuaries, Vol. 13(1) pp. 51-58.

    NOAA National Benthic Inventory (NBI). Undated. Capitella capitata collection information. Available online.

    Petraitis P. 1985. Females inhibit males' propensity to develop into simultaneous hermaphrodites in Capitella species I (Polychaeta). Biological Bulletin, Vol. 168(3) pp. 395-402.

    Qian PY and FS Chia. 1994. In situ measurement of recruitment, mortality, growth, and fecundity of Capitella sp. (Annelida: Polychaeta). Marine Ecology Progress Series 111:53-62.

    Reish DJ. 1957. The relationship of the polychaetous annelid Capitella capitata (Fabricius), to waste discharges of biological origin. United States Public Health Services. 208: 195-200.

    Rosenberg R. 1976. Benthic faunal dynamics during succession following pollution abatement in a Swedish estuary. Oikos, Vol. 27(3) pp. 414-427.

    Sears NE and AJ Mueller. 1989. A survey of the polychaetes of Bolivar Flats and Big Reef, Galveston, Texas. The Southwestern Naturalist 34:150-154.

    Tenore KR. 1977 Growth of Capitella capitata cultured on various levels of derlved from different sources. Limnology and Oceanography 22:936-941.

    Tenore K and RB Hanson. 1980. Availability of detritus of different types and ages to a polychaete macroconsumer, Capitella capitata. Limnology and Oceanography, Vol. 25(3) pp. 553-558.

    Tenore KR amd EJ Chesney, Jr. 1985. The effects of interaction of rate of food supply and population density on the bioenergetics of the opportunistic polychaete, Capitella capitata (type I ). Limnology and Oceanography 30:1188-1195.

    Tsutsumi H and T Kikuchi. 1984.Study of the life history of Capitella capitata (Polychaeta: Capitellidae) in Amakusa, South Japan including a comparison with other geographical regions. Marine Biology 80:315-321.

    Ward TJ, and PA Hutchings PA. 1996. Effects of trace metals on infaunal species composition in polluted intertidal and subtidal marine sediment near a lead smelter, Spencer Gulf, South Australia. Marine Ecology Progress Series 135:123-135.

    Warren LM. 1977. The ecology of Capitella capitata in British waters. Journal of the Marine Biological Association of the United Kingdom 57:151-159.

    Wilson WH. 1990. Competition and predation in marine soft-sediment communities. Annual Review of Ecology and Systematics 21:221-241.

    Wu B, Qian P, and S Zhang S. 1988. Morphology, reproduction, ecology and isoenzyme electrophoresis of Capitella complex in Qingdao. Acta Oceanol Sinica 7: 442-458.

Report by: J. Masterson, Smithsonian Marine Station
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Page last updated: October 1, 2008

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