BIOTIC Species Information for Cordylophora caspia
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Researched byDr Harvey Tyler-Walters & Paolo Pizzolla Data supplied byMarLIN
Refereed byThis information is not refereed.
General Biology
Growth formTurf
Feeding methodPassive suspension feeder
Mobility/MovementPermanent attachment
Environmental positionEpibenthic
Typical food typesSmall zooplankton, small crustacea, oligochaetes, insect larvae and probably detritus. HabitAttached
BioturbatorNot relevant FlexibilityHigh (>45 degrees)
FragilityFragile SizeSmall-medium(3-10cm)
HeightUp to 10 cm Growth Rateca 0.05-0.1 mm/hr
Adult dispersal potentialSee additional information DependencyIndependent
General Biology Additional InformationGrowth 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.

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,
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