Its peristomium measures the same as its succeeding segments, and is bilobed, forming two anterior wings that cover the prostomium dorsally.
12.
The prostomium and peristomium can be variously fused, either completely distinct, or comprising a joint structure of a peristomial ring and a tentacular crown.
13.
The head consists of a Prostomium ( part of the mouth ) and a peristomium ( area around the mouth ) and carries paired appendages ( palps, antennae and cirri ).
14.
The consists of a prostomium ( a section for the mouth opening ) and a peristomium ( section around the mouth ) and has paired appendages ( palps, cirri and antennae ).
15.
The head consists of a prostomium ( part of the mouth's opening ) and a peristomium ( area around the mouth ) and utilized paired appendages ( palps, antennae and cirri ).
16.
The suborder name " Symphyta " derives from the Greek word " symphyton ", meaning " grown together ", referring to the group's distinctive lack of a wasp waist between prostomium and peristomium.
17.
The segments develop one at a time from a growth zone just ahead of the pygidium, so that an annelid's youngest segment is just in front of the growth zone while the peristomium is the oldest.
18.
The mouth of polychaetes is located on the peristomium, the segment behind the prostomium, and varies in form depending on their diets, since the group includes predators, herbivores, filter feeders, scavengers, and parasites.
19.
They are similar in appearance to Hesionidae, with a peristomium often with two pairs of tentacular cirri ( with 1 pair or 0 in some species ), reduced or absent notopodia, and a lack of pharyngeal jaws.
