Heteractis magnifica

Heteractis magnifica is found only in the tropical regions of the Indo-Pacific Ocean. Occurring from the Red Sea to Samoa, H. magnifica lives in marine waters of South East Asia, Northern Australia, and the Western Pacific Regions. From Australia, the range of H. magnifica extends all the way to the Ryukyu Islands. (Allen and Fautin, 1992; "Animal-World", 1998; Guck, 2004)

Heteractis magnifica is found in marine reefs ranging from 1 to 50 meters deep. It prefers warm waters ranging from 24 degrees C to 32 degrees C. This species resides in clear waters with a strong current. Abundance and colonial or solitary behavior correlates with depth; those that are closer to the surface are solitary and smaller, while those that are deeper tend to form colonies. Animals found to the leeward of the prevailing swell of the water tend to be in denser populations than those in more exposed marine locations. ("Animal-World", 1998; Brolund, et al., 2004; Guck, 2004; Richardson, et al., 1996)

Heteractis magnifica has the basic morphology of most anemones, living its entire life in the polyp form (looking like a cylindrical column with tentacles). This species has a sticky foot on a pedal disc, and an oral disc which contains the mouth and surrounding tentacles. Heteractis magnifica is the second largest in size of all sea anemones. The oral disc reaches 1 m in diameter or can be as small as 1.25 cm. Typically H. magnifica is between 300 and 500 mm in diameter. The foot, which is used to anchor the animal to various hard surfaces, is also larger than most anemones. The oral disc of an anemone is a flat to slightly curved structure with a mouth in the center, used for both feeding and producing waste. The oral disc can be yellow, brown, or green and is often slightly elevated so that the mouth protrudes out. (Allen and Fautin, 1992; "Animal-World", 1998; Guck, 2004; Horton, 1997)

Many tentacles surround the oral disc; these are located within 20 to 30 mm of the mouth. The lower part of the tentacles closest to the mouth is the same color as the oral disc (usually shades of brown), but the distal portion of each tentacle can vary in color. Tentacles can range in color from red, pink, purple, orange, and green, but are most commonly tannish. Tentacles are about 75 mm long, and some are branched. Heteractis magnifica has characteristic swollen or bulb-like tips on the finger shaped tentacles. Within these tips are cnidocytes, which contain many nematocysts, structures for delivering toxins use in capturing food and defense. (Allen and Fautin, 1992; "Animal-World", 1998; Guck, 2004)

Adult and baby magnificent anemones are very similar in physical appearance. Magnificent anemones lack skeletons and can grow large when nutrient levels are high, but they can shrink when nutrients are scarce. Members of this species can also look like a ball if they contract their tentacles so that only a tuft of tentacles, if any, remain visible. (Guck, 2004)

When anemones reproduce sexually, their fertilized eggs develop into a planula larvae which settles on the ocean floor and develops into a polyp. When anemones reproduce asexually, they form new anemones directly from the parent as an exact replica. ("Animal-World", 1998; Guck, 2004)

There are no data on mating systems in Heteractis magnifica. (Guck, 2004)

Heteractis magnifca can reproduce sexually or asexually. In sexual reproduction, the male releases his sperm first to stimulate the female to release her eggs. This external fertilization leads to the development of a ciliated planula larvae. Asexual reproduction can occur by budding, binary fission, or pedal laceration (when part of the pedal disc breaks off to form a new anemone). Most asexual reproduction occurs in the winter. The presence of the symbiotic clown fish Amphiprion chrysopterus can increase the amount of asexual reproduction and general growth. Anemones found with two A. chrysopterus species had faster fission rates than those without this symbiotic species. (Guck, 2004; Holbrook and Schmitt, 2004)

There is no parental involvement in the sexual or asexual reproduction process.

The longevity of Heteractis magnifica in the wild is unknown, but estimated that some of these anemones are hundreds of years old. In captivity, the longest lifespan is 80 years. ("Animal-World", 1998; Guck, 2004)

Heteractis magnifica can be either solitary or colonial. Solitary animals tend to cluster together once they reach a specific size. Some small animals cluster together resembling one large animal, but it is said that these smaller individuals are likely clones. The magnificent anemone is motile when trying to re-position itself to obtain more sunlight. This species moves by creeping on its basal disc, or by letting the tide carry it. Members of this species tend to stay sedentary for most of their lives. Anemones can be semi-aggressive and sting other anemones that invade their space. ("Heteractis magnifica (Family Stichodactylidae)", 2007; "Animal-World", 1998; Brolund, et al., 2004; Guck, 2004)

If H. magnifica is attacked, it produces a chemical that is released into the water to warn other anemones that a predator is in the area. The anemone then contracts its tentacles into a ball form for protection. (Mrvos, 2003)

Heteractis magnifica has no ears, eyes, or centralized nervous system. This anemone has nerves in the body wall that are able to communicate with other parts of the body and sense the environment around it. The species possesses three separate nerve "nets" that determine contraction of tentacles in response to the environment. The TCNN and SS1 pathways represent the fast and slow responses of tentacles to mechanical stimulation (for TCNN) and chemical stimulation for the SS1 pathway. Both nerve nets excite the ectodermal muscles via the stimulation of the multipolar nerve net that expands the body of the anemone. The SS1 nerve net, also called the ectodermal slow system, seems to also be responsible for the pre-feeding response (opening of the mouth), and the escape response. (McFarlane and Lawn, 1991; McFarlane, 1984; Mrvos, 2003)

Heteractis magnifica is carnivorous, feeding on small fish, shrimp, isopods, amphipods, mussels, sea urchins, and plankton. This species also absorbs sulfur, nitrogen, and other essential nutrients for growth from the waste of the symbiotic clownfish that live within the tentacles of the anemone. The clownfish also occasionally carries chunks of food to its host.

The anemones use their stinging nematocysts to capture prey that touch them, and then bring them in to the oral disc to digest. They also contain symbiotic algae that produce glucose as a product of photosynthesis, which the magnificent anemone uses. ("Animal-World", 1998; Guck, 2004; Horton, 1997)

Anemones have stinging cells called nematocysts that keep away most predators. The protein toxins that are released are ichthyotoxic; if marine or freshwater fish are exposed to .5 micrograms/mL of the toxin, they die within 2 hours. (Mebs, 1994)

Magnificent sea anemones are hosts to many symbiotic clownfish, which chase away any nibbling predators, especially bristle worms. The clownfish are immune to the nematocysts and gain protection from the anemones' stinging tentacles. ("Animal-World", 1998; Guck, 2004)

Magnificent sea anemones are prey on fish and invertebrates.

Heteractis magnifica are hosts to many types of clownfish that are resistant to the toxins produced by the anemone. This mutualism benefits both animals, because the clownfish chase away predators of the anemone and bring the anemone food, while gaining protection within the tentacles of the anemone for themselves and their young. Some shrimp also live beneath the oral disc of the anemone, but are not resistant to the toxins. They clean the underside of the magnificent anemone. ("Animal-World", 1998; Guck, 2004)

Heteractis magnifica is the most photographed species of anemone and is popular as an aquarium pet. ("Animal-World", 1998)

A new protein "hmGFP" was cloned from the tentacles of H. magnifica. The properties of this protein were homologous to that of the green fluorescent protein (GFP), and it has shown promising possibilities in biotechnology research. (Tu, et al., 2003)

Other than its capacity to sting, Heteractis magnifica has no adverse effects on humans. (Horton, 1997)

Heteractis magnifica is not listed on the IUCN Red List, CITES appendices, or the US Endangered Species Act list.