Phylum: Cnidaria Ectopleura crocea Class: Hydrozoa, Hydroidolina Order: Anthoathecata, Aplanulata A tubular hydroid Family: Tubulariidae Taxonomy: Ectopleura crocea was original- manubrium is a pale yellow-orange. The or- ly described by Agassiz, 1862 as Parypha ganism’s dominant color comes from the pink crocea, though it was soon after classified to red hydranths (Ricketts et al. 1985). as Tubularia crocea (Allman 1871). The pri- Body: mary synonyms are T. crocea and Pinauay Pedicel: The hydrocaulus is un- crocea (Mills et al. 2007). There has been branched, crooked, and covered with fine much debate about the appropriate genus "hairs" (diatoms). The stiff perisarc extends to for this species, but Ectopleura crocea is the base of the hydranth (Mills et al. 2007). now generally accepted (van der Land et al. Hydranth: The hydranth lacks a 2001; Schuchert 2015). Additional syno- theca. The manubrium is surrounded by a nyms include Tubularia ralphi, T. gracilis, T. whorl of tentacles, is simple, and circular (Fig. australis, and T. warreni (Schuchert 2010). 3). Gonaphore: The gonophores each Description contain an abortive medusae, or gonomedu- General Morphology: The only form of E. sae. They are in clusters on stalks (racemes) crocea is the large, colonial polyp. Each pol- between the two whorls of tentacles (Fig. 3). yp has a stem (hydrocaulus) covered in a Within the gonophores develop the planulae rigid perisarc and an athecate hydranth with larvae, which leave the gonophore but remain a mouth (manubrium), stomach, tentacles, in close association with the polyp (Kozloff and gonophores (Figs. 1, 2). 1983). Female gonophores have short distal Medusa: The medusa is not free-swimming crests (Mills et al. 2007), with 4-8 flattened (Ricketts et al. 1985); though it is biologically bladelike tentacles at the apical end (Kozloff similar to other free-swimming hydromedu- 1987). Male gonophores lack tentacles (Mills sa, it is entirely retained in the tissue of the and Strathmann 1987). gonophore (Kozloff 1983). Tentacles: Tentacles are fili- Cnidae: form (thread-like), simple, and in two whorls (oral and aboral, Mills et al. 2007). The proxi- Polyp: mal, or aboral, whorl consists of long, extend- Size: The colony grows in large ed feeding tentacles at the base of the hy- bushy clusters up to 15 cm (Ricketts et al. dranth, while the distal, or oral, whorl has 1985). Stems grow to 2 cm long, and short tentacles usually contracted around "flowers" (the hydranth) are up to 1 cm when mouth (Figs. 2, 3). There are similar numbers extended. The genus Ectopleura contains of distal and proximal tentacles (Kozloff species that are considered the largest athe- 1987). Older specimens have more tentacles cate hydroids (Kozloff 1974). than young ones; juveniles will have only 10 Color: The hydrocaulus is white to proximal tentacles. light tan, the feeding tentacles (proximal and distal) are transparent white, the gono- Possible Misidentifications phores are light pink and dark coral, and the The family Tubulariidae is composed of A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Piazzola, C.D. 2015. Ectopleura crocea. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. hydroids with a thick perisarc and stolons to the Pacific via ship bottoms (Mills et al. (ground-level shoots connecting branches). 2007). It has been found on both sides of the Species in this family have at least two ten- Atlantic and from the Gulf of Alaska to south- tacle whorls and gonophores between the ern California, and thrives in northern temper- oral and aboral whorls. The medusae in this ate oceans (Ricketts et al. 1985). family can be either free-swimming or re- Local Distribution: This species is common tained, have four radial canals, a simple in Oregon and California estuaries, and mouth, and few tentacles. Divisions of the seems to be a more northern species. In the family into its genera are based on presence Coos Estuary, it has been found in South of stolons, texture of the stem, origin of the Slough, Charleston, and Fossil Point. perisarc, and morphology of the medusa Habitat: One of the most prominent fouling stage (Schuchert 2012). organisms, E. crocea is often found on under- The genus Ectopleura is composed of sides of floating docks, boat bottoms, and hydroids with only two tentacle whorls, one wharf pilings (Ricketts et al. 1985, Mills et al. oral and one aboral. The perisarc originates 2007). It thrives in cold water with good move- below the connection between the hydranth ment. In the lab, it is not bothered by strong and stem, and ends at the base of the hy- light (Mackie 1966). It is one of the inverte- dranth. The stem is a hollow tube with 0-5 brate organisms most resistant to poisons, ridges. Stolons are present. The medusae such as copper (Barnes in Pyefinch and can be free-swimming or retained Downing 1949). It lives in the low intertidal (Schuchert 2012). and down to 40 m (Mills et al. 2007), and is The other common local species of always attached to solid substratum rather Ectopleura, E. marina, is a small, solitary than mud or sand (Kozloff 1987). athecate (without a cup-like theca) hydroid Salinity: Collected at 30. of the outer coast. Its stalk is usually about 2.5 cm long, it has fewer distal tentacles Temperature: Specimens respond badly to than proximal ones, and it is less showy warm water in the lab and will lose hydranths. than E. crocea, as it does not occur in Regression occurs with summer temperatures clumps as the latter does. While E. crocea (Mackie 1966). Ectopleura crocea is usually branches extensively from its base, E. mari- found at temperatures above 18°C, but can na does not (Kozloff 1983). be kept in laboratories at 14° C (Mills and Other athecate hydroids often have some capitate (knobbed) tentacles as Strathmann 1987). adults, i.e. Cladonema, Hydrocoryne. Of Tidal Level: Low intertidal; subtidal to 40m those with only threadlike tentacles, some (Haderlie et al. 1980) like Hydractinia and Eudendrium have only a Associates: On floating docks, the colonial single whorl of tentacles, not two whorls as Ectopleura crocea and its substrate constitute in Ectopleura crocea. Others, such as Turri- topsis and Clava have tentacles in scattered a rich microecosystem. Some of the most patterns rather than in whorls (Rees and common epibionts are suctorian protozoans, Hand 1975). diatoms (especially in fall, darkening stems) The species Ectopleura larynx looks (Pyefinch and Downing 1949), caprellid and similar to E. crocea, but is not found in Ore- tube-building amphipods, isopods, copepods, gon. and mussels. Ectopleura crocea has, howev- Ecological Information er, become a nuisance to mussel-growing aq- Range: The type locality is Boston Harbor uaculturists. The hydroid will foul on juvenile (Agassiz 1862). This species is native to the mussels, restricting their growth by impeding northern Atlantic Ocean, and was introduced their ability to filter water and by competing for A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] food. Additionally, E. crocea will eat incom- association with the polyp (Kozloff 1983) and ing mussel larvae, which decrease settle- metamorphose into the actinulae (Fig. 5). ment rates in commercial mussel facilities Actinulae are mobile, crawling larvae shaped (Fitridge and Keough 2013, Fitridge 2011). A like little polyps with the characteristic whorls pycnogonid, Anoplodactylus erectus, is par- of tentacles (Kozloff 1983). To develop into asitic in the digestive tract of Ectopleura cro- the adult polyp form, the actinulae moves cea in southern California, distending the away from its “parent” polyp and settles on polyps abnormally (Ricketts et al. 1985, the nearby substratum (Kozloff 1983). There Rees and Russell 1937). Some amphipods is no swimming stage. One polyp can produce (Stenothoe) are immune to E. crocea’s nem- over 100 gonomedusae (not simultaneously) atocysts (Mackie 1966). The colonies also (Miller 1976). Gonomedusae most distal on provide a habitat for the egg masses of the racemes (stalks) mature soonest (Mackie some benthic opisthobranchs (Mills et al. 1966). Mature male gonomedusae are white, 2007). while immature have a red stripe. The mecha- Abundance: Colonies can be quite dense nism for spawning and larvae release is not under the right conditions of water and cur- known (Miller 1976), but possibly could be rents. In ideal conditions, actinulae are re- due to a change in light intensity and water leased August-October and February-March speed (Pyefinch and Downing 1949). In one (Elkhorn Slough, CA), and, in less favorable area, only one species of Ectopleura will be environments, August-November (Mills and sexually active at a time (Miller 1976). Strathmann 1987). In warmer waters the Larva: Actinula larvae are the larval stage; species shows a seasonal pattern of high these larvae attach to substrate and become abundance during cool months and low a new polyp. They can have up to 10 capitate abundance during warm; it has also been (knobbed) tentacles containing nematocysts; decreasing in abundance since about 1980, visible inside are the manubrium and distal likely due to increasing ocean temperatures tentacle buds (Fig. 5). In E. larnyx, tentacles (Mediterranean Sea) (Di Camillo et al. can vary from 6 to 13, though most have 10 2013).