The Beaded Anemone, Heteractis aurora is also known as the Aurora anemone or Beaded Sand Anemone . They obtain their name from the swellings on the tentacles which give the impression of strings of beads. They are not that common on the East African coast and are never seen in great densities, but in some areas there are many of them.
The beaded anemone has an oral disc which grows up to 25 centimeters in width. There are distinctive gaps in the tentacles and they tend to have a large gap between those around the mouth and those on the circumference. They are far flatter than for example the Magnificent anemone and the Bubble Anemones. The oral disc has alternating light and dark lines that radiate outwards.
The tentacles themselves also have alternating colors between the swellings which accentuates the impression of a string of beads. Their colours vary from a light brown to a darker brown and green colour. Underwater some specimens appear to be a purple blue color but when one puts bright light on them they are a brown colour.
BEADED ANEMONE IN THE WILD
The Beaded anemone prefers sandy areas rather than being on the reef its self and is more common on rubble areas and even on sandy areas. Very occasionaly one sees one on the reef itself in a crevice. On the Tanzanian coast they are found from 1 meter to at least 25 meters. They will occasionally have a single clownfish in them and seven species of clownfish have been recorded in them across their range. We have never seen the Skunk clown, Amphiprion akallopisos in them , but it is not uncommon to see a single young Allards Clownfish, Amphiprion Allardi in them as can be seen in the image lower down. On rare occasions one will see an adult Allard’s Clownfish in the Beaded Anemone as pictured below.
Also on rare occasions one sees the Domino Damselfish, Dascyllus trimaculatus in them. They are known as nursery anemones and the young clownfish seem to start off with them until they can find another more suitable anemone and a partner.
In all probability this is because when the anemone is fully extended there are large gaps in the tentacles and the clownfish prefer more consistent tentacles for protection. Additionally the Beaded Anemone tends to sit very flat on the substrate whereas the other shorter tentacled anemones such as Carpet anemones usually have folds in them for the Clownfish to shelter in.
Only very seldomly does one find a Porcelain Anemone Crab, Neopetrolisthes maculatus in a Beaded Anemone and usually if there is, then there is a single specimen whereas there is usually a pair in the other species of anemone that they inhabit.
Beaded anemones are very quick to retract into the sand or rubble if they believe they are under threat.
The Beaded Anemone is widespread throughout the tropical and subtropical waters of the Indo Pacific, from the east coasts of Africa to the Red sea, Across to Japan and south to Australia.
As with other anemones the Beaded anemone forms symbiotic relationships with single celled algae. The anemone benefits from the algae’s photosynthesis, namely oxygen and food in the form of glycerol, glucose and alanine. The algae in turn obtain protection against herbivores from the anemones stinging cells and good exposure to light.
They also use their venomous cells or nematocysts in the tentacles to sting and capture prey such as small fish and planktonic matter. Additionally they obtain some nutrition from a commensal relationship with clown fish which sometimes reside in the anemones tentacles.
Beaded anemones can reproduce asexually by budding or splitting and by sexual reproduction. In sexual reproduction males release sperm into the water, which stimulates females to release eggs into the water. Fertilization occurs when the two meet. Anemones eject eggs and sperm through the mouth. The fertilized eggs then develop into planula’s which settle and grow into a single polyp. Because they tend to be isolated one quite often sees a Beaded anemone that has split by asexual reproduction. With other more communual anemones such as the Magnificent Anenome this is more difficult to pickup.
Due to their habit of moving around an aquarium anemones can be difficult to keep and seldom situate themselves exactly where you want them. They can ambulate several feet per day and often head for the area of maximum water movement and light. The Bubble tip anemone which is captive bred is probably what most people should be looking at because it is easy to keep and is aesthetically the best looking,
Many unscrupulous dealers dye anemones before putting them out into the market and any unusually brightly colored anemone should be avoided. The Beaded Anemone is not the ideal choice for Clownfish as they prefer other anemone species. Because of this they are not everyone’s first choice for their tank. Nevertheless they are an unusual feature and some people may enjoy them. They prefer deep sand with rubble and once settled will make an interesting feature.
If one dives in the same area consistently, Beaded Anemones often move around considerable distances and sometimes leave an area completely. Probably they are floating off and being carried off by tidal movements but this is speculation.
As with corals, beaded anemone drop their algae when conditions are unfavorable. Usually in the wild they reabsorb them when the conditions become more favorable. This was witnessed on the Tanzanian coast in 2016 when water tempratures were in excessof 32 C for a prolonged period of time. Most if not all of the anemones seem to have survived.
BEADED ANEMONE CLASSIFICATION
The Reef Guide fishes, corals, nudibranchs & other invertebrates: East and South Coasts of Southern Africa by Dennis King & Valda Fraser
Assistance from Joe Rowland