Capitella capitata (Fabricius, 1780)

Synonyms:
Lumbricus capitatus Fabricius, 1780
Lumbricus litoralis Johnston, 1827
Saenuris barbata Grube, 1860
Capitella capitata McIntosh, 1915

Distinguishing characteristics
Thorax with 9 chaetigers.
First 6-7 segments with capillary chaetae only.
Male with 4 genital hooks arranged in a diagonal cross mid-dorsally between chaetigers 8 and 9.

Species description
Body long, cylindrical, rather fragile, narrowing at each end, broader anteriorly, lacking any appendages, 100 segments. Prostomium conical, as long as broad. Thorax with 9 chaetigers. First 6-7 segments with capillary chaetae only, 7th segment with both capillary chaetae and hooks and segment 8-9 and following segments with hooks only. A single genital pore opens mid-dorsally between chaetigers 8 and 9, in the female an oval swelling, in the male in the middle of four stout chaetae (genital hooks) arranged in a diagonal cross. Pygidium without cirri.

Size
Up to 120 mm for 100 segments.

Color
Alive life red-brown to purple.
In alcohol red-brown to transparent.

Habitat
From eulittoral down to 1000 m deep. In muddy sand or rich mud and under stones. Often indicates pollutes conditions.

Mobility
Mobile.

Feeding
Carnivore.
Surface deposit feeder.

Life cycle

Distribution
Cosmopolitan.