Physical Description

Aulactinia veratra is commonly found in intertidal zones, along the coast of Australia and New Zealand, adhering to and between rocks with a well developed pedal disc. The vivid green coloration of this animal has earned it the common name 'Green snakelock anemone' (Figures 1-3). During low tide, when the animal is immersed, the tentacles are retracted and the column appears black (Figure 4). Brown and red forms are known but are less common.


Figure 1: Aulactinia veratra adhered to two boulders in a rock pool at Point Carwtwright (QLD).



Figure 2: Aulactinia veratra adhered to a hard substrate buried beneath sand (Point Cartwright, QLD). The oral disc is partially covered with sand.


Figure 3: Aulactinia veratra adhered to the underside of a boulder lining a rock pool. The columns of the two individuals on the right are adorned with sand and shell grit.

The columns of A. veratra collected from WA, VIC,NSW and New Zealand have been recorded as averaging 20mm in height (Edmands & Fautin, 1991). Mature specimens observed in situ in the intertidal zone of Point Cartwritght (QLD) frequently exceeded this, and were more inline with measurements made by Fautin et al. (2008) of specimens collected from QLD, NSW and TAS, whose columns were up to 60mm when expanded. A. veratra has a stout, streamlined bodyplan, even more so when the tentacles and trunk are contracted. This should be expected from an animal living in an environment where strong flow velocities are encountered (Koehl, 1977)_.


Figure 4: Two retracted individuals at low tide. (Point Cartwright, QLD)

Longitudinal rows of verrucae, adhesive sucker-like warts, are found along the length of the column. Individuals observed in situ had their columns adorned with sand and shell grit (Figures 3, 5-7). This may be a mechanism to prevent desiccation, or as protection against predators during low tide. They may also function in reducing drag forces produced by tidal waves, as proposed by Koehl (1977) for the intertidal anemone Anthopleura xanthogrammica.


Figure 5: Aulactinia veratra at low tide. Coarse sand and shell grit is adhered to the column by verrucae. (Point Cartwright, QLD)


Figure 6: Aulactinia veratra at low tide. Coarse sand and shell grit is adhered to the column by verrucae. (Point Cartwright, QLD)


Figure 7: Aulactinia veratra at low tide. Coarse sand and shell grit is adhered to the column by verrucae. (Point Cartwright, QLD)

The oral disc of A. veratra bears regularly arrayed tentacles around the outer margin, with the mouth at the centre. Tentacles are conical, blunt tipped and the same colour as the column (Edmands & Fautin,1991). Various numbers of tentacles have been reported, ranging from 24 to 124 (Edmands & Fautin, 1991).