Switching Between Deposit and Suspension Feeding in Coastal Zoobenthos
77
Dinophilids. These tiny, interstitial polychaetes are also, as an alternative to
deposit feeding, capable of catching suspended particles with a ciliary mucoid
mechanism that enables them to feed on bacteria, protozoans, unicellular
algae, diatoms, and organic debris (Fauchald and Jumars 1979).
Nereids. Nereids are common in shallow water and all species have jawed
eversible pharynges. With few exceptions they are all omnivorous (Fauchald
and Jumars 1979) (Fig. 4.1g), but only one species, Nereis diversicolor, seems
capable of suspension feeding with the aid of a mucus net-bag suspended
within its tube (Riisgard 1991; Riisgard et al. 1992, 1996b; Vedel and Riisgard
1993). The importance of suspension feeding in N. diversicolor may vary from
one population to the next, and the habit may perhaps be entirely missing in
some populations, see detailed account in 'Example I' (Sect. 4.2).
Oweniids. The only oweniid so far investigated seems to be Owenia fusiformis which has a shallow, lobed tentacular crown. This worm is capable both
of suspension feeding and surface deposit feeding. During deposit feeding,
the lips are used to pick up particles directly. Quantitative investigations
comparing time devoted to each mode are still lacking (Fauchald and Jumars
1979).
Sabellids. A suspension-feeding habit is the most important one in this
family (Riisgard and Ivarsson 1990). In addition, Manayunkia aestuarina is
also capable of feeding by turning over and touching the substratum with its
tentacular crown in a form of surface deposit feeding (Fig. 4.1h). The method
may be of primary importance in freshwater and brackish water sabellids
(Fauchald and Jumars 1979).
Spionids. Spionids are generally considered to be surface deposit feeders,
using their ciliated palps to select food particles from the sediment surface
(Dauer 1991, 1994; Dauer and Ewing 1991). However, certain species can
switch from deposit to suspension feeding by catching plankton on the palps
when the water current velocity and/or the concentration of suspended
material becomes sufficiently high (Fig. 4.1 c) (Self and Jumars 1978; Dauer et
al. 1981; Shimeta and Jumars 1991; Qian and Chia 1997; Shimeta and Koehl
1997; Williams and Mcdermott 1997); some examples are Polydora cornuta
(Dauer et al. 1981), Boccardia polybranchia (Qian and Chia 1997), Scolelepis
squamata (Dauer 1983), Spiophanes bombyx (Dauer et al. 1981), Spio setosa
(Dauer et al. 1981), Marenzelleria viridis (Dauer 1997), and Paraprionospio
pinnata (Dauer 1985).
Pygospio elegans is the most versatile of the spionids studied to date. It can
filter by building a mucus net within its tube, it can catch plankton with the
77
Dinophilids. These tiny, interstitial polychaetes are also, as an alternative to
deposit feeding, capable of catching suspended particles with a ciliary mucoid
mechanism that enables them to feed on bacteria, protozoans, unicellular
algae, diatoms, and organic debris (Fauchald and Jumars 1979).
Nereids. Nereids are common in shallow water and all species have jawed
eversible pharynges. With few exceptions they are all omnivorous (Fauchald
and Jumars 1979) (Fig. 4.1g), but only one species, Nereis diversicolor, seems
capable of suspension feeding with the aid of a mucus net-bag suspended
within its tube (Riisgard 1991; Riisgard et al. 1992, 1996b; Vedel and Riisgard
1993). The importance of suspension feeding in N. diversicolor may vary from
one population to the next, and the habit may perhaps be entirely missing in
some populations, see detailed account in 'Example I' (Sect. 4.2).
Oweniids. The only oweniid so far investigated seems to be Owenia fusiformis which has a shallow, lobed tentacular crown. This worm is capable both
of suspension feeding and surface deposit feeding. During deposit feeding,
the lips are used to pick up particles directly. Quantitative investigations
comparing time devoted to each mode are still lacking (Fauchald and Jumars
1979).
Sabellids. A suspension-feeding habit is the most important one in this
family (Riisgard and Ivarsson 1990). In addition, Manayunkia aestuarina is
also capable of feeding by turning over and touching the substratum with its
tentacular crown in a form of surface deposit feeding (Fig. 4.1h). The method
may be of primary importance in freshwater and brackish water sabellids
(Fauchald and Jumars 1979).
Spionids. Spionids are generally considered to be surface deposit feeders,
using their ciliated palps to select food particles from the sediment surface
(Dauer 1991, 1994; Dauer and Ewing 1991). However, certain species can
switch from deposit to suspension feeding by catching plankton on the palps
when the water current velocity and/or the concentration of suspended
material becomes sufficiently high (Fig. 4.1 c) (Self and Jumars 1978; Dauer et
al. 1981; Shimeta and Jumars 1991; Qian and Chia 1997; Shimeta and Koehl
1997; Williams and Mcdermott 1997); some examples are Polydora cornuta
(Dauer et al. 1981), Boccardia polybranchia (Qian and Chia 1997), Scolelepis
squamata (Dauer 1983), Spiophanes bombyx (Dauer et al. 1981), Spio setosa
(Dauer et al. 1981), Marenzelleria viridis (Dauer 1997), and Paraprionospio
pinnata (Dauer 1985).
Pygospio elegans is the most versatile of the spionids studied to date. It can
filter by building a mucus net within its tube, it can catch plankton with the