The Response of Protodrilus symbioticus (Giard) (Archiannelida) to Light
1966; Wiley; Volume: 35; Issue: 1 Linguagem: Inglês
10.2307/2689
ISSN1365-2656
Autores Tópico(s)Isotope Analysis in Ecology
ResumoInterstitial animals would, in general, be expected to avoid high light intensities, but surprisingly few experiments have been carried out to analyse their response to light. The interstitial archiannelids Nerilla antennata Schmidt (Goodrich 1912) and Trilobodrilus heideri Remane (Boaden 1963) have been shown to be strongly negative to light, accumulating in shaded areas. Nerilla exhibits a negative photokinesis, moving away from regions of high light intensity, whilst Trilobodrilus turns at random at the boundary until it faces the shaded area into which it proceeds, a behaviour pattern referred to as klinokinesis by Fraenkel & Gunn (1940) and as phobotaxis by Pfeffer (1904). The archiannelid Protodrilus symbioticus, measuring 2 mm in length and 70 ,u in breadth, occurs locally in large numbers. It is easily removed from sand samples (Gray 1965) and is a convenient animal to study in the laboratory. It was therefore chosen as a suitable interstitial form in which to study the response to a light/shade boundary and to a light gradient. Although Swedmark (1954), who described the morphology in detail, stated that P. symbioticus had no obvious light receptors, Boaden (1963) believed that light played an important part in controlling the distribution of this species as with other interstitial animals.
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