Balanophyllia elegans , colloquially known as orange cup coral or jewel coral, is an anthozoan of the family Dendrophylliidae. The scientific name of the species derives from the Greek ‘balanos‘, meaning acorn, and ‘phyllia‘, meaning leaf, while ‘elegans‘ in Latin translates as elegant, referring to the shape and striking appearance of this coral. Balanophyllia elegans is found in the waters of the Pacific Ocean, mainly on the west coast of North America, from southern Alaska to Baja California. It inhabits intertidal and shallow subtidal zones (<10 meters), specially in rocky areas where they adhere to hard surfaces.
Balanophyllia elegans is a solitary coral, which means that it does not form colonies like other corals. It generally measures between 1 and 2.5 centimeters in diameter, although it can sometimes reach 3 cm. Its structure is composed of a cup-shaped calcareous calyx that gives it its colloquial name. It has a bright coloration that varies from yellow to deep orange, although some variations may show reddish or brownish tones. This vibrant coloration is one of its most distinctive features and sets it apart from similar species, such as Balanophyllia regia, which tends to be duller in color and less symmetrical in shape. The walls of its calyx are relatively thick and covered with small radial septa that help to identify it. Unlike many other coral species, Balanophyllia elegans does not have zooxanthellae algae in its tissues, which means that it does not rely on photosynthesis for energy.
The feeding habits of Balanophyllia elegans are primarily carnivorous. This coral feeds by capturing small planktonic organisms such as copepods, crustacean larvae and other microinvertebrates that pass close to its tentacles. The coral’s tentacles are covered with stinging cells called cnidocytes, which paralyze the prey on contact. Once captured, the prey is transported to the oral disc, where it is ingested and digested. Because it does not contain symbiotic algae in its tissue, it is completely dependent on the capture of these live prey to obtain its food, which makes it more active during nighttime hours when plankton is more abundant.
Balanophyllia elegans reproduces both sexually and asexually. Sexual reproduction generally occurs during the spring and summer months when water temperatures are warmer. This coral is gonochoric, so individuals are either male or female. Fertilization is internal, and the resulting planktotrophic larvae, known as planulae, are released into the water where they swim freely before settling on a suitable substrate to develop a new individual. Asexual reproduction occurs by budding, where the coral produces small shoots that eventually separate from the main individual to form new corals.
A curious fact about Balanophyllia elegans is its ability to tolerate variable environmental conditions, such as changes in salinity and water temperature, which allows it to survive in intertidal zones where other corals would not be able to thrive. In addition, due to its ability to reproduce both sexually and asexually, this species can quickly adapt to changes in its environment, which contributes to its wide distribution along the Pacific coast.
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