Preliminary experiments with Bryozoa in a simple apparatus for producing continuous water currents
- D. Jebram1
© Biologischen Anstalt Helgoland 1970
1. An improved type of bubble-pump and an apparatus for producing continuous water currents, designed especially for utilization of planktonic food, are described.
2. The operation of the apparatus is easy; current speeds can be regulated from 0 to about 1/2 m/sec.
3. The apparatus can be used for experiments on small animals and plants, especially sessile and hemisessile forms.
4. BryozoansFarrella repens, Conopeum seurati, andC. reticulum, exposed to water currents at 15° C, exhibited no preferred growth direction relative to the current direction.
5. In fast currentsFarrella repens andElectra monostachys covered their substratum densely with zooids.
6. In slow currentsElectra monostachys andE. pilosa revealed positive rheotropic growth responses.
7. Slow water currents appear to stimulateElectra pilosa to form erect colony parts.
8. Water currents probably influence the development of ball-formed colonies inElectra pilosa formaerecta. The ball-form may be the result of an interaction between retarding effects of strong water currents at the periphery and stimulating effects of slow water currents in the interior parts of the ball.