Scolelepis squamata is a slender, bluish-green worm with a maximum length of about 14 cm (5.5 in) and over two hundred segments when fully grown.

The prostomium (head) is diamond-shaped and has four eyes, arranged in a trapezoid fashion, two long slender palps, and no central antenna.

The dorsal lobes of the parapodia are long and thin and are fused to the gills for half their length.

Examination of the contents of the gut showed sediment particles, faecal pellets of other animals and a variety of embryos, larvae and juvenile prey.

[4] On the south coast of Britain, this worm breeds between March and July; sperm and eggs are released into the sea where fertilisation takes place, and the larvae are planktonic for about five weeks before settling on the seabed and developing into juvenile worms.