Tidepool or Small Brown or Mudflat Anemone (Sea Anemones of New Zealand)

Tidepool or Small Brown or Mudflat Anemone

Anthopleura aureoradiata

Description ²

Common
Habitat
In hollows on mudstone or on shells, such as cockles, or stones on mudflats or tidal pools. In rocky intertidal and mudflats.

Column
Brown, yellow, and white. Brown column widening towards the top, up to 40mm high. Covered with small pale yellow or grey verrucae bumps in lines from top to bottom, prominent at the top margin. Has a groove with 24 marginal spherules at the base of the tentacles. Broods internally.

Oral disc
Brown or grey with slit mouth. With yellow mark on the peristome. 12 to 18mm diameter.

Tentacles
Up to 72 tentacles in 4 whorls, brown, mottled with irregular patches of silvery white, all about the same length. The tentacles are blunt and appear to have hollow tips.

Distribution
Throughout NZ and in South Australia.

An edited version of Transactions and Proceedings of the Royal Society of New Zealand 1868-1961, Art. XXXIV, Volume 41, 1908, pp367-369:
Notes on a New Zealand Actinian, Bunodes aureoradiata
By F. G. A. Stuckey, M.A. :

Specific Character.—Yellow radii in 6 groups of 3.

Pedal-disc. slightly wider than the column; the edge undulate to correspond with the vertical rows of warts. On each undulation are 2 or sometimes 3 perforations, through which, when irritated, the animal projects nematocysts torpedo-fashion, and in such a manner as at first sight to suggest feeble acontia.

Column.—Cylindrical. In full expansion it is higher than the breadth. The lower half is light or yellowish-brown, upper half greenish-brown. There are 24 vertical rows of warts or verrucæ: near the bottom of the column these become mere markings; they increase in size as they ascend the column, culminating in a row of 24 white beads at the bases of the outer whorl of tentacles.

Tentacles.—Conical and gently tapering. Pore at tip. Colour bronze-green, like that of the oral disc. The tentacles are very sensitive, and completely and quickly retractile; they number 48, and are arranged in 4 whorls, the formula being 6 + 6 + 12 + 24 = 48.

Oral Disc. The “mouth” is borne on a prominent peristome surrounded by a broken circle of yellow, from which extend 6 groups, each consisting of 3 radiating yellow lines with a shorter yellow line between each 2 groups. These yellow radii correspond to the first 3 whorls of tentacles, the tentacles of the 4th whorl being set opposite to the interspaces.

Æsophagus.—The colour is greyish-white. Each side of the œsophagus is thrown into 2 large lobes. Outgrowths of the mesoglœa, with corresponding foldings of the ectodermal lining of the œsophagus, give a much folded appearance, which in cross-sections somewhat resembles an exaggerated starfish.

Dimensions.—Oral disc 12 mm. wide in a good specimen. Height in full expansion rather more than 12 mm. The longest tentacles are about 8 mm.

Locality and Habits. The animal lives between tide-marks, almost completely buried in sand and mud. The presence of the zooxanthellæ probably enables it to adopt this habit.

An edited version of Actiniaria of New Zealand Part 1, 1951.
A check-list of recorded and new species a review of the literature and a key to the commoner forms
by G. Parry, M.Sc :

The column is straight and pillar-like, a little narrower at the base, widening towards the tentacles. The lines of mesenterial insertion down the column are shown as white lines. The brown colour of this anemone is probably due, at least in part, to the presence of the symbiotic zooanthellae.
The surface of it is covered with verrucae, arranged in longitudinal rows, their size diminishing from top to bottom. These verrucae sometimes attach pieces of detritus to the column, but this is not common. The verrucae tend to form compound structures just below the top of the column. The verrucae pale yellow, or grey.
There is a collar carrying 24, rather prominent, marginal spherules (less in smaller specimens, and +/- one or two fully grown ones). Marginal spherules are white,

The tentacles are in 4 cycles, 6, 6, 24, 36. A large specimen has about 70 tentacles. The different cycles are all much of the same size. The tentacles are brown, mottled with irregular patches of silvery white.

The oral disc is wide and flat, the tentacles always being held well out from the disc in expanded specimens. The peristome is small and the mouth slit-like. The colour is very constant, a combination of brown and yellow and white. The basis of Stuckey's specific name—' 6 yellow radii in groups of three ', are 6 yellow marks on the peristome. Beyond this there is a ring of 6 M's, and beyond this again, a ring of 6 W s . All this is on a pattern of brown. The upper part of the column is brown, fading to a cream at the base.

Extremely abundant, found in mud-flats of estuaries, and the shallow intertidal pools, throughout New Zealand;

Tuatara: Volume 6, Issue 2, December 1956
Seafloor Animals from the Region of Portobello Marine Biological Station, Otago Harbour
By Patricia M. Ralph and J. C. Yaldwyn

Venus shell anemone. A small, 12 to 18 mm high, brown and yellow anemone frequently epizooic with the Venus shell Austrovenus stutchburyi; column straight and pillar-like when fully extended, a little narrower at the base, widening upwards to the tentacles; surface covered with small adhesive yellow or grey warts, the upper part of the column brown in colour, fading to cream at the base; tentacles simple, brown mottled with irregular patches of silvery white; the colour of the animal rarely varies. Found throughout New Zealand.

References ²

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