BIOTIC

BIOTIC Species Information for Cordylophora caspia
All Taxonomy Biology Distribution Reproduction

Researched by	Dr Harvey Tyler-Walters & Paolo Pizzolla	Data supplied by	MarLIN
Refereed by	This information is not refereed.
General Biology
Growth form	Turf	Feeding method	Passive suspension feeder Predator
Mobility/Movement	Permanent attachment	Environmental position	Epibenthic Epifaunal Epilithic Epiphytic Epizoic
Typical food types	Small zooplankton, small crustacea, oligochaetes, insect larvae and probably detritus.	Habit	Attached
Bioturbator	Not relevant	Flexibility	High (>45 degrees)
Fragility	Fragile	Size	Small-medium(3-10cm)
Height	Up to 10 cm	Growth Rate	ca 0.05-0.1 mm/hr
Adult dispersal potential	See additional information	Dependency	Independent
Sociability	Colonial
Toxic/Poisonous?	No
General Biology Additional Information	Growth form Growth form is highly variable in Cordylophora caspia. The colony of consists of a mass of stolons (hydrorhizae) growing across the surface of the substratum. Growth is apical, with side stolons arising at right angles. Upright hydrocauli bear apical polyps (hydranths), and side branches at 45° (Fulton, 1961).The degree of branching, length and spacing of hydrocauli, cell size, size and shape of polyps and the number and length of tentacles vary with environmental conditions (Fulton, 1962; Kinne, 1970, 1971; Arndt, 1989). For example, colonies have short, polyps that grow directly from the hydrorhiza at 0.5psu; more elongate polyps with longer tentacles and multiply branched uprights at 15psu, but smaller polyps and less branched uprights at 30psu than at 15psu (see Kinne 1970, 1971 for review; Arndt, 1989, Gili & Hughes, 1995). Gaulin et al. (1986) noted that predation by the nudibranch Tenellia fuscata resulted in denser colonies. Growth rates Growth rates are variable depending on environmental or laboratory conditions. Growth in number of polyps is exponential, the colonies doubling in polyp number every 2-4 days, although growth rate can very as much as two-fold even under standard conditions (Fulton, 1961, 1962). In addition, although old colonies could reach as much as 2000 polyps in size growth rates decreased with age (Fulton, 1962). Fulton (1961) reported that uprights grew at 0.05mm/hr while stolons extension rates vary from 0.1mm/hr (Fulton, 1961) to 2-3mm³/day (Chester et al., 2000). Fulton (1962) reported that growth rates varied with temperature, salinity, ionic composition, oxygen tension and feeding rate (see sensitivity). Seasonal changes Cordylophora caspia dies back in late autumn and over-winters as dormant stolons and resting stages (menonts) inside the remnants of the uprights (see Roos, 1979 for figure, Arndt, 1989, Jormalainen et al. 1994). Arndt (1989) reported that colonies died back in autumn when the temperature fell to about 10 °C only to germinate in spring when the temperature exceeded 5 °C. Roos (1979) reported that colonies died back in October and new polyps budded again in early spring in the Netherlands. In the Baltic Sea growth was maximal in spring, uprights reaching maximal height at the peak of sexual reproduction in July, with a decline after sexual reproduction, and subsequent growth in August (Jormalainen et al., 1994). However, in one year, Jormalainen et al (1994) noted that the colonies regressed to the dormant condition after sexual reproduction then started growing again by mid August. Feeding Hydroids are passive carnivores that capture prey that swim into, or are brought into contact with their tentacles by currents. Prey are then killed or stunned by the nematocysts born on the tentacles and swallowed. Diet varies but is likely to include small zooplankton (e.g. nauplii, copepods), small crustacea, chironomid larvae, detritus and oligochaetes, but may include a wide variety of other organisms such as the larvae or small adults of numerous groups (see Gili & Hughes, 1995).
Biology References	Barnes, 1994, Hincks, 1868, Allman, 1871-1872, Gili & Hughes, 1995, Arndt, 1989, Arndt, 1984, Kinne, 1970, Kinne, 1971, Fulton, 1961, Fulton, 1962, Chester et al., 2000, Roos, 1979, Jormalainen et al. 1994), Gaulin et al., 1986,