Tubularia crocea
pink-hearted hydroid
(Also: pink-mouthed clustered hydroid)

Tubularia crocea, also known as Ectopleura crocea in the scientific community, is commonly referred to as the pink-hearted hydroid, or the pink-mouthed clustered hydroid. It lives mainly in the northwest Atlantic ocean, including the area around New England, though it can be found from New Brunswick to Florida. In the Chesapeake Bay, Tubularia crocea is limited to the mouth of the bay and is most prevalent in the summer(WDFW 2001; Lippson 1984; Collins 1981 )

Tubularia crocea grows profusely on rocks and boat docks. It does not, however, live in the intertidal zone, so it's not very likely that one would find Tubularia crocea in this area though this invertebrate prefers a habitat consisting of gravel or sand (Animal Species in the Tillies Basin Area 2001).

Hydroids are small (each about 400 micrometers in size), colonial animals that grow on rocks and seaweed and appear as "bushy growths." The hydroids appear as tufts of long and tangled stems. Individually, each hydroid has a stem-like feature, the pedicel, and a flower-like feature, the hydranth. Each hydranth has one row of tentacles around the central mouth and one proximal row, consisting of 16-25 shorter tentacles. Tubularia crocea has gray stalks and pink hydranths, thus leading to its common names of "pink-hearted hydroid" or "pink-mouthed clustered hydroid," (Coelenterata 2001; Organisms of the Woods Hole Region 2001; Collins,Henry Jr. 1981).

Tubularia crocea is a colonial invertebrate that groups itself together with other invertebrates of the same species in order to form dense colonies. It anchors itself onto rocks or boatdocks in order to maintain stability and avoid being washed away with the current. Tubularia crocea are also very sensitive to increases in temperature (Coelenterata 2001).

The strength of the stinging power of Tubularia crocea's tentacles paralyzes its prey and then the tentacles draw the food into the invertebrates' mouths. The food supply of Tubularia crocea consists of zooplankton, phytoplankton and small detritus (CCS - Stellwagen Bank - Other Invertebrates (non-plankton));Animal Species in the Tilles Basin Area, 2001).

Tubularia crocea considered a nuisance species since it was introduced into the Atlantic environment approximately twenty years ago. (It was first found in the San Juan Islands in the 1930's but not discovered in the areas it inhabits now until the 1980's). Though most non-native species are unable to form self-sustaining colonies, if they do establish themselves, they can greatly affect the flora and the fauna of the ecosystem. Non-Indigenous Species (NIS) can bring disease and parasites to economically valuable native species and therefore adversely affect the economy. They also can compete for food with the native species or even use the native species as a food source, thus greatly altering the ecosystem (Mills 1998; Non-Indigenous Aquatic Nuisance Species (ANS),1998).

Tubularia crocea feeds on zooplankton, phytoplankton and small detritus, thus helping to avoid build-up in the environment. Also, it is a food source for nudibranchs, echinoderms, and other fish that humans regularly consume, including cod, haddock and flounder (Animal Species in the Tillies Basin Area 2001).

Very little information was found on conservation of this species since it is not of threatened or endangered status. However, efforts are made to keep environmental conditions under control in order to maximize biodiversity.

In experimental studies, the larvae of Tubularia crocea was observed to determine the importance of active and passive processes during its settlement. It was hypothesized that the larvae would have preferences of settlement based on topographic heterogeneity, that substratum complexity would modify these preferences and that behavior of the larvae on or close to the substratum mediates these preferences. All three hypotheses were found to be true. T. crocea larvae chose the most complex kind of panels and, for the most part, settled on surfaces that were the most exposed (Marine Ecology Progress Series 1996).