Nephtyidae is a taxonomic family of worms. They are commonly referred to as catworms.

Characteristics

Nephtyidae are pale, clearly segmented polychaetes with a small pentagonal prostomium

Prostomium

Prostomium is the first body segment in annelid worms. It is in front of 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...

with two pairs of small antennae. Their segments are little differentiated and have a rectangular cross-section.

Nephtyids are active predators, with a strong muscular proboscis, armed with two well developed jaws.

They can dig relatively fast through sandy sediments. They can also swim with sinuous movements.