prostomium


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prostomium

(prō-stō′mē-əm)
n. pl. prosto·mia (-mē-ə)
The anterior portion of the head of an annelid worm, situated in front of the mouth.

pro·sto′mi·al (-əl) adj.

prostomium

that part of the head of some annelids and molluscs which lies in front of the mouth.
References in periodicals archive ?
a) Dorsal view, b) detail of dorsal view, c) dorsal view of prostomium and first four segments, GOL: globular ocular lobes, CMA: ceratophore of the median antenna, EL: elytrophores, d) neuropodium of segment 5, NB: neurosetae bidentate, NBwET: neurosetae bidentate with one extra tooth, e) parapodium from segment 5, PCGP: parapodium covered with globular papillae, CI: ventral cirrus, f) elytrum from segment 2, g) dorsal cirrus from segment 3.
Prostomium trapezoidal, with three antennae, paired palps, and a pair of red eyes.
websteri showed variation in palp pigmentation pattern, the shape of the anterior edge of the prostomium, the shape of the major spines on chaetiger 5, and shape of the pygidium (Table III).
Other authors (Ewing, 1984; Read, 2000) have suggested that the first segment posterior to the prostomium, or peristomium, is dorsally subdivided, and includes two segments, a position that we agree with, due to the fact that in C.
Remarks: This species is recognized by the absence of a caruncle (fleshy outgrowth of the nuchal organs in the prostomium) and neurochaetae with simple hooks (Yanez-Rivera, 2009).
During metamorphosis, the once-planktonic larva's body elongates, trochal cilia are shed, the prostomium elongates, and capillary setae protrude (Biggers et al., 2012).
Prostomium with a medium antenna originated from the middle zone of the eye pair (Fig.
n.]: Prostomium transverse, short, longitudinally striated; dorsal setae of anterior body region single, ventral setae doubled, no setae in posterior body region; ventral tuberculum single.
The specific name naso is a noun derived from the Latin word nasus (nose) and the Roman personal name Naso, emphasizing the nose-like prostomium of this worm.
Morphologically, it is characterized by a blunt prostomium forming a hood over its mouth.
The operculum (Figure 1a) is a thick muscular plate which forms the anterodorsal surface of the (fused) prostomium and peristomium.
Antennae and peristomial cirri are articulated; the antennae have teardrop shaped distal segments and the 3 to 4-segmented peristomial cirri reach to the middle of the prostomium. Branchiae are pectinate and begin at setiger 3, they are longer than the articulated dorsal cirri.