The Orientation of Barnacles to Water Currents
1957; Wiley; Volume: 26; Issue: 1 Linguagem: Inglês
10.2307/1788
ISSN1365-2656
Autores Tópico(s)Crustacean biology and ecology
ResumoInvestigations have shown that barnacle larvae select suitable sites in relation to (a) depth (Hutchins 1952), (b) illumination (Pomerat & Reiner 1942, McDougall 1943, Gregg 1945, Weiss 1947, Barnes, Crisp & Powell 1951), (c) surface contour (Crisp & Barnes 1954), and texture (Moore & Kitching 1939, Pope 1945, Gregg 1948, Pyefinch 1948, 1950), (d) the presence of previously settled individuals of the same species (Knight-Jones & Stevenson 1950, Knight-Jones 1953), or of related species (Knight-Jones 1955) and (e) the velocity gradient of currents at the surface of the substratum (Crisp 1955). If the current flow relative to the substratum is too great, the cyprids fail to attach (Smith 1946, Korringa 1948). In addition to selecting a particular site, they orientate at settlement to surface contour and light (Barnes, Crisp & Powell 1951) and possibly also to water movement (Crisp 1955). Orientation along grooves (rugotropism) has been investigated by Crisp & Barnes (1954) who showed that it was a sensitive reaction invoked by contact with irregularities in the surface. Rugotropism was shown to override other orientation responses. In spite of statements to the contrary by Visscher (1928) the conclusion that cypris larvae orientate positively to light at settlement appears inescapable. Hiro (1939), McDougall (1943), and Pyefinch (1948) all recorded positive responses, and Barnes, Crisp & Powell (1951) showed a positive orientation to light in Balanus balanoides and B. crenatus while in Elminius modestus the proportion of individuals orientating towards the light could be correlated with the proportion of illumination falling in a given sector. They suggested that orientation to light might possibly have survival value since it would bring the eyes of the adult into the direct path of the incident light; nevertheless they thought it probable that this reaction might be non-functional, a continuation of the positive reaction to light shown throughout the planktonic phase. Knight-Jones & Crisp (1953) made observations of cypris larvae of B. balanoides during the setting process
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