Burrowing in the Antarctic anemone, Halcampoides sp., from Signy Island, Antarctica.
Antarctic anemones of the genus Halcampoides inhabit low intertidal and shallow subtidal zones. They readily burrow into soft sediments following disturbance. The process of re-burying was recorded using time-lapse video in the aquarium of the British Antarctic Survey with specimens of a species collected from the shallow sublittoral (<1 m depth) at Signy Island. Penetration of the sediment takes place by a similar mechanism to that employed by burrowing anemones such as Peachia hastata from lower latitudes. Penetration initially is brought about by peristaltic contractions that involve only the modified base, or physa. Later, as the column becomes buried, the peristaltic contractions start in the upper part of the scapus and pass down the column before extending the physa. At this stage penetration is aided by contractions of the longitudinal muscles that draw the column down into the sediment. At 0 degrees C the frequency of initiation of peristaltic contractions down the column, and of contractions of the longitudinal muscles are on average >1.6 and >4.0 times slower, respectively, compared with those of Peachia hastata from Scotland, recorded at approximately 11-14 degrees C. Q(10) values calculated from these data are in the range 1.4-3.0, and thus provide little evidence supporting any evolutionary acclimation of the processes involved in burrowing has occurred in Halcampoides from the Antarctic, although the data are limited.
Ansell
AD
Scottish Association for Marine Science, P.O. Box 3, PA34 4AD, Argyll, Oban, UK
Peck
LS