Various different colours have been described. Almost all except blue. Exact information on the colours link below. This anemone can change the colour of its tentacles, the larger one adopting a brown and cream combination resembling the colours of the bird called the Jenny Wren Troglodytes troglodytes.

Colours Link

Photograph showing the longitudinal lines which are less pronounced than in 
Sagartiogeton undatus.

Similar species:   Sagartia ornata.  Sagartia elegans.

Breeding: 

Habitually viviparous, although this is rarely recorded (I have never seen it). The method of the anemone developing within the body cavity is not confirmed. Research into similar viviparity in Actinia equina seems to indicate reproduction is asexual. 

Habitat:

This anemones buries about 10 to 50 mm down underneath the sand but attached to a rock. The anemone stretches its column up so that the oral disc and spread of tentacles are level with the sand surface. If disturbed the anemone can disappear completely beneath the sand. A large population can be present but invisible. The column has to be adaptable to squeeze between the rocks, which can be embedded close together in the sand. 

Link to a picture of a typical intertidal habitat.
 

Sagartia troglodytes with the tentacles retracted underneath a rock, with a drooping goblet appearance.
 

This sea anemone can be abundant on suitable shores exposed by low spring tides (e.g. Worthing, Sussex). However, these shores are often depositing shores in the spring and summer, when the anemone may actually migrate towards the shore as the sand is deposited, and grow larger under the mussel beds on the pier supports. However, during the winter gales the sand is often scoured away leaving just the rocks behind with very little sand. In these circumstances the anemone can demonstrate a variety of unusual shapes (including the goblet shape), because the column lacks the sand support it needs. This can also be seen when all but the very smallest of this species of anemone attaches itself to the underneath of rocks. 

This anemone appears to be intolerant of temperatures in excess of 25ºC. 

Behaviour:

Usually this anemone is medium/strongly adherent and can only be detached from a rock with great care.

The small spider crab has a fascination with all sea anemones
 
 

Food:

Proportionately large crustaceans, including small crabs. Mostly caprellids, amphipods. 

Range:

All British coasts. Norway - Mediterranean (probably only in the north and west). 

Additional Notes:
Supplementary Information 1
Supplementary Information 2 

Information wanted: Please send any records of this sea anemone, with location, date, who discovered it, how it was identified, prevalence, common name and any other details to 
Shorewatch Project EMail Glaucus@hotmail.com. 
All messages will receive a reply. 

Shorewatch Project