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SIPHON SIZE AND DEPTH IN BENTHIC BIVALVES
WINTER SUMMER Fig. 9. Mya arenaria. Burymg depth (cm ± SB)
of three si/e classes as a function of siphon
weight in w inter i left panel: n = 246)and in summei
iriglu panel; n = 321).
300 400 500 200 300 400 500
siphon weight (mg)
siphon
width
20 30 40 50
size (mm)
siphon width = 0.23x sized-!"
r»0.99 n=166
60 70 80
Fig. 10. Mya arenaria. Width of the siphon (mm ± SE) as a function
of shell size.
104
thus larger individuals use mine siphon weighl per tinit
length.
Discussion
Burying depth and shell size
The depth/size relation of Mya (Fig. 2) corresponds
with the qualitative descriptions given for the German
and Danish Wadden Sea (Thamdrup 1935. Linke
1939. Kiihl 1951. 1981) and with the data from California
(Vassallo 1971) and ihe eastern eoasi of North
America (Blundon & Kennedy 1982b).
Quantitative data of the burying depth of Cerastoderma
were not found in the literature, but descriptions
given by Thamdrup (1935). Linke (1939), Baggerman
(1953). Kristensen (1957). Jackson & James (1979)
correspond with Fig. 3.
Reading & McGrorty (1978) and Ratcliffe et al.
(1981) measured the depth of Macoma on the English
East Coast. They used the 'slice technique', bul when
a correction is made (see Materials and Methods), their
depth/size relationship agrees with the depth measurements
on Schiermonnikoog. the Dutch Wadden Sea
(Hulscher 1973) and with our data: they found spal
(< 4 mm) in the upper one cm during the whole year,
whereas the large Macoma (8 to 15 mm) burrowed at I
lo 3 cm in summer and at c. 4 cm in winter. Macoma