Most worms are hidden from view beneath rocks and in sediment. There are, however, some worms that live in tubes which may be encountered by the beachcomber. These sedentary worms have numerous feeding tentacles which they use to catch food suspended in the water.

Coiled tube worm and Keel worm Spirobis spirobis (Linnaeus) and Pomatoceros triqueter (Linnaeus)

The coiled tube worm and the keel worm live in chalky tubes and capture food suspended in the water using their crown of tentacles.

Both worm species have both male and female sex organs but cross fertilization between individuals still occurs. Sperm from one animal is washed into the tube of another. The fertilized eggs are then kept within the tube until the larvae hatch out. The larvae of the coiled tube worm only remain in the open water for a few hours before they settle on seaweeds in the local vicinity. The keel worm’s larvae may drift in the open water for up to two months before settling on rocks on the shore. Both species of worm live for about one and a half years.

Large numbers of coiled tube worms may be found on the serrated wrack (Fucus serratus). The spiral shape of their tubes allow the worms to withstand the flexing of seaweed fronds.

• Habitat

  • Found on rocks on the lower shore. Found on the lower shore on wracks.

• Key Identification Features

  • White calcareous tube.

  • Tiny crown of tentacles.

  • Curvy tube with a ridge running along the upper surface (Keel worm). Tightly coiled tube (Coiled tube worm).

  • Tube up to 3 cm in length (Keel worm). Tube up to 3 mm in diameter (Coiled tube worm).

Honeycomb worms Sabellaria alveolata (Linnaeus)

These worms build impressive honeycomb-like structures out of sand. Living in colonies, each worm binds together sand to form a tube. The interlocking tubes sometimes form huge reefs on rocks and boulders. When the tide is out, the worm blocks the tube entrance with its bristly head to prevent itself from drying out. When the tide is in, the worm uses its tentacles to catch food suspended in the water.

Honeycomb worms are found on the south-west and west coasts. Particularly spectacular colonies are found at Duckpool, north of Bude, Cornwall and at Hele Rock Bay, near Otterton, Devon.

It is important that the unusual reefs of the honeycomb worm are treated with care. Despite their solid appearance they are very fragile.

• Habitat

  • Found on the lower shore on rocks close to sand.

• Key Identification Features

  • Tube made of sand grains, often forming huge brown honeycomb-like structures.

  • Worm reddish-brown.

  • Body of worm up to 4 cm in length.

Peacock worm Sabella pavonina (Savigny)

Out of the water, all that can be seen of this animal is its tube made of mud and sand. Once immersed in water, the worm expands its fan of feathery tentacles. The peacock worm uses its beautiful crown of tentacles to catch particles suspended in the water. Small particles are drawn towards its mouth for food. Large particles, however, are rejected, while medium sized particles are mixed with mucus and added to the tube. The worm’s tentacles disappear in a flash down into the tube if the worm is disturbed.

There are both male and female peacock worms. Eggs and sperm are released into the open water where fertilization takes place. The eggs then develop into larvae and are dispersed in the currents before settling on rocks.

• Habitat

  • Found on soft sediment on the low shore in shallow water.

• Key Identification Features

  • Crown of tentacles striped purple, brown or red.

  • Worm in a tough, membranous tube.

  • Tube up to 5 cm in length.