Candelabrum australe

Contracted hydroid cap-like in appearance, the gonophore bearing blastostyle region forming a decorative circular basal rim and the body a tapering crown.

Hydrorhiza comprising numerous short stolons covered by perisarc radiating from below the base of the hydranth but obscured by the living animal; stolons terminating in small circular disks firmly attached to the algal thallus; hydrorhiza entirely covered by a thin greyish layer of mucus.

Body not extending into the blastostyle region. Body tentacles capitate, globular, numbering about 1500 (Briggs 1928), crowded together on the contracted hydranth but separated when body expanded; tentacles borne on stout transparent peduncles and richly armed with nematocysts.

Blastostyles crowded on lower body, bearing clusters of 6–10 apically flattened tentacles on stout peduncles; tentacles armed with 100s of large nematocysts.

Hydranth bisexual, gonophores fixed sporosacs, male and female gonophores borne separately on stout branched blastostyles among clusters of tentacles; blastostyles comprising numerous developing and mature gonophores;

Mature gonophores of both sexes spherical, c. 1 mm in diameter with a flattened circular apical cap. Larvae may be visible inside mature female gonophores. Actinula larvae flattened, typically lobate but variable in shape, capable of slow, barely perceptible movement.

Colour: The living hydroid is dark orange in colour showing paler longitudinal bands when the body is extended; mature female gonophores paler yellow; apices of the blastostyle tentacles and the apical cap of mature gonophores with a dark brown granular band.

The tapering body of the hydranth is remarkably extensile and prehensile, extending rapidly from 2–6 cm, sweeping back and forth over the algal substrate somewhat reminiscent of an elephant’s trunk. It is highly sensitive to stimulus, contracting rapidly when touched.

Temperate southern Pacific: Australia and New Zealand.

Subtidal, on algae, particularly kelp Ecklonia radiata.