Prostomium
Encyclopedia
Prostomium is the first body segment in annelid
worms. It is in front of (but does not include) the mouth, being usually a small shelf- or lip-like extension over the dorsal side of the mouth. It sometimes bears antennae
and eyes. It often functions like a kind of overlip when the animal is feeding. The shape and composition of prostomium are important for annelid systematics.
The prostomium often also has appendages such as palps and tentacle
s or cirri. Some polychaetes have a posterior extension with sensory function on it, called caruncle. Another kind or sensory organ called nuchal organ (or a variety of it, the nuchal epaulette) is a ciliated pit or groove at the posterior end of the prostomium .
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
worms. It is in front of (but does not include) the mouth, being usually a small shelf- or lip-like extension over the dorsal side of the mouth. It sometimes bears antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
and eyes. It often functions like a kind of overlip when the animal is feeding. The shape and composition of prostomium are important for annelid systematics.
The prostomium often also has appendages such as palps and tentacle
Tentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s or cirri. Some polychaetes have a posterior extension with sensory function on it, called caruncle. Another kind or sensory organ called nuchal organ (or a variety of it, the nuchal epaulette) is a ciliated pit or groove at the posterior end of the prostomium .