Acropora spathulata is the iconic Australian Staghorn Coral | Reef Builders

Acropora spathulata is the iconic Australian Staghorn Coral | Reef Builders


Last week, we reported about probably the most popular staghorn coral from Australia, Acropora microclados, a.k.a the Strawberry Shortcake. This time, we will tell you about another iconic Australian staghorn coral, Acropora spathulata.

A problematic species?

First of all, having seen quite a few different specimen in their natural habitat, one thing struck me; It’s one of a hell of a colorful species! Unfortunately, the spathulata Acro is very hard to find in aquarium colonies that are as colorful as their reef counterparts.

An adaptive species:

Having toured with Ultra Coral Australia and guru coral spotter Nic Dos Santos, I’ve seen quite a large sampling of different reef habitat along the Great Barrier Reef. We discovered that Acropora spathulata is a very adaptive species, and is found in quite a multitude of diverse reef habitats, from inshore turbid shallow reef, to deeper crystal clear water offshore reefs.

Glowing on an inshore reef flat, almost exposed at low tide. With light intensity as high as it could be!

Having said that, there is a place where they are more common and their color is a lot more intense and this place is inshore reef flats. This part of the reef is very shallow, partially emerged at low tide, so in super shallow water, and thus very high light exposure. We haven’t taken a PAR meter on this part of the reef, but we assume that the light intensity is as high as it could be.

The maximum light intensity found on this reef is probably one of the reason, most aquarist can’t really reach the full color potential of Acropora spathulata, they just can’t give them enough light – a quantity of light that would burn many other species of corals, including a lot of other Acropora species.

A close up of the common purple Acropora spathulata on a shallow turbid inshore reef

This is also the part of the reef, where the tidal water passes through. The corals on the shallow inshore reef are ‘run over’ all day long by tides to the point that we can only access this part of the reef, at slack tide. So in addition to the stratospheric light intensity, the water flow is also as intense as it can be. And with good flow, usually comes extremely good water quality, with high pH, high oxygen level, and quite low nutrients.

Particularities of Acropora spathulata:

Acropora spathulata is a very close twin of Acropora millepora, just in a thicker form, which is why both species were confused for a long time. The particularity of these two is to have this chain-mail, compacted, scale-like radial corallites with prominent lower lips while axial corallite tips are much bigger and tubular.

Specialized colony shape?

Colonies of A. spathulata are corymbose (pillow-shaped), with short, thick vertical branchlets growing out of a horizontal base. This colony form is a very good adaptation to filter out particles out of a laminar flow – the side horizontal branches create turbulence in the water layer, that push particle to settle in the tentacle rich center of the colony. When the tide gets low, the colonies literally bathe in a soup of plankton since the shape of the colony is a perfect food trap.

The conclusion is that this species is built and adapted to the most extreme conditions of the reef. Spathulata prefers the highest light and flow, but also a good reasonable feeding so it should be placed in the highest position, as close as possible to the lights, with good water flow going over it. Probably that a little bit of nutrients is not too bad, if the light and flow are super high but if you succeed in giving it what it needs, you’ll be rewarded with one of the most beautiful staghorn coral colonies. 

a rapidly expanding branch of A. spathulata


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