SCATOLOGICAL STUDIES O F THE BIVdLVIA (MOLLrSCA)
333
velocity of the cloacal current. In an actively feeding oyster the ribbon
is maintained in a horizontal position along the axis of the current, but
being heavier than the sea water it sinks down to the bottom as soon
as the cloacal current slows down or ceases. Large masses of fecal ribbons accumulate on the bottom a short distance from the opening of
the cloaca. The ribbon remains intact for 2 to 3 days until it is disintegrated through decomposition and mechanical disturbance. The
appearance of the fecal masses of the oyster is typical and can be
recognized by their shape. It was shown by Moore (1931) that specific
identification of fecal pellets can be made for a number of marine
invertebrates. Fecal ribbons of oysters contain many live cells-diatoms, dinoflagellates, yeast, and others which are not killed by the
gastric and intestinal juices and can be recultured.” (Galtsoff, 1964,
p. 228, Figs. 205, 207).
“ Freshly deposited oyster feces consist of short green or brown
segments from about 1 to 5 mm long. In cross section, they are thickened filaments about 1 mm across with recurved edges and a low
median longitudinal ridge. Under certain laboratory conditions, production of fecal ribbons was continuous, but production of short segments was most frequent. Pseudofeces were similar in color but were
ejected as clumps loosely aggregated with mucus and occasionally as a
continuous string without definite form.” (Haven and Morales-Alamo,
1966, p. 493.) (Pellet-type 111-lOa).
55. Saxostrea echinata (Quoy and Gaimard) (Pl. 4-42)
“Pellets of the present species are ribbon-shaped, and carry a
modicum of mucus. Both lateral edges of the ribbon are thickened and
slightly turn dorsalwards, and the dorsal side is fairly raised along the
median line to form a low dorso-median ridge, while the opposite ventral side is flattened and unsculptured. Pellets are coarse in texture,
soft and friable in consistency and dark green in colour. They are
formed of rather coarse materials containing numerous larval shells of
some lamellibranch. For an animal with shell 5.8 cm long and 2.0 cm
wide, ribbons are 1.27 mm in width on an average ” (Arakawa, 1965,
p. 17, P1. V, Fig. 47.) (Pellet-type 111-10u.)
Spondylidae
56. Spondylus harbatus Rve
face sculpturing (Pellet-type ‘1111-10).
Locality : Shirahama, Wakayama, Japan.
This species sheds pellets consisting of a film!: ribbon with no sur-
333
velocity of the cloacal current. In an actively feeding oyster the ribbon
is maintained in a horizontal position along the axis of the current, but
being heavier than the sea water it sinks down to the bottom as soon
as the cloacal current slows down or ceases. Large masses of fecal ribbons accumulate on the bottom a short distance from the opening of
the cloaca. The ribbon remains intact for 2 to 3 days until it is disintegrated through decomposition and mechanical disturbance. The
appearance of the fecal masses of the oyster is typical and can be
recognized by their shape. It was shown by Moore (1931) that specific
identification of fecal pellets can be made for a number of marine
invertebrates. Fecal ribbons of oysters contain many live cells-diatoms, dinoflagellates, yeast, and others which are not killed by the
gastric and intestinal juices and can be recultured.” (Galtsoff, 1964,
p. 228, Figs. 205, 207).
“ Freshly deposited oyster feces consist of short green or brown
segments from about 1 to 5 mm long. In cross section, they are thickened filaments about 1 mm across with recurved edges and a low
median longitudinal ridge. Under certain laboratory conditions, production of fecal ribbons was continuous, but production of short segments was most frequent. Pseudofeces were similar in color but were
ejected as clumps loosely aggregated with mucus and occasionally as a
continuous string without definite form.” (Haven and Morales-Alamo,
1966, p. 493.) (Pellet-type 111-lOa).
55. Saxostrea echinata (Quoy and Gaimard) (Pl. 4-42)
“Pellets of the present species are ribbon-shaped, and carry a
modicum of mucus. Both lateral edges of the ribbon are thickened and
slightly turn dorsalwards, and the dorsal side is fairly raised along the
median line to form a low dorso-median ridge, while the opposite ventral side is flattened and unsculptured. Pellets are coarse in texture,
soft and friable in consistency and dark green in colour. They are
formed of rather coarse materials containing numerous larval shells of
some lamellibranch. For an animal with shell 5.8 cm long and 2.0 cm
wide, ribbons are 1.27 mm in width on an average ” (Arakawa, 1965,
p. 17, P1. V, Fig. 47.) (Pellet-type 111-10u.)
Spondylidae
56. Spondylus harbatus Rve
face sculpturing (Pellet-type ‘1111-10).
Locality : Shirahama, Wakayama, Japan.
This species sheds pellets consisting of a film!: ribbon with no sur-