Freshwater paddleworms (Namanereis)

Taxonomic group

Nereidae: Namanereis

Diagnostic features

Namanereis tiritiae is our only truly freshwater polychaete (paddleworm). The polychaetes are annelids (segmented worms) and they are characterised by their fleshy “paddles” (parapodia) on each body segment. Namanereis has a long white body, but they are fragile and can be difficult to collect intact. Antennae, palps, a proboscis and jaws may be visible when the head is magnified.

[Namanereis]. Image: Stephen Moore Image — Namanereis. Image: Stephen Moore

[Namanereis] head with extended proboscis. Image: Stephen Moore Image — Namanereis head with extended proboscis. Image: Stephen Moore

Typical habitats

Namanereis are found only in specific parts of the North Island; our records are from unshaded sandy-gravelly streams in the Manawatu and Hawkes Bay regions.

Feeding

They are primarily deposit feeders, collecting fine organic matter from bottom sediments.

Indicator value

Hard bottom: unassigned
Soft bottom: unassigned; general paddleworm value 6.7

The tolerance values (ranging from 0 to 10) give an indication of which are the sensitive taxa (values of 8 or more) and which are the tolerant taxa (values of 3 or less). For more information see: Indicator species

Namanereis is too rarely recorded to be a useful water quality indicator. This genus has not been assigned tolerance values but the Class Polychaeta (paddleworms) has a soft bottom tolerance value of 6.7 (no hard bottom value has been assigned).