Net Fire Coral

Millepora dichotoma, commonly known as the net fire coral, is a hydrozoan species characterized by a colony of polyps with a calcareous skeleton. This colonial hermatypic coral forms colonies that can reach up to 60 cm in width, with clumps of colonies spanning several meters. Initially, they develop as encrusting corals that adhere to hard substrates and later evolve into different growth forms, including lace-like, leaf-like blades, and box-work structures. The specific growth form of Millepora dichotoma is influenced by factors such as depth, location, and water turbidity. Lace-like structures tend to thrive in deeper, less turbulent waters, while box-work forms are better suited for harsher environments.

As with other hermatypic corals, the metabolic processes of fire corals rely on zooxanthellae. These symbiotic organisms provide vibrant colors to Millepora dichotoma, support their structural growth, and aid in nutrient cycling. Being part of the cnidaria phylum, these corals possess nematocysts, which contain venom that can be fatal to many organisms. However, there have been no recorded fatalities in humans. Nonetheless, contact with Millepora dichotoma can cause extremely painful sensations, burn-like wounds, and skin irritation that can persist for up to two weeks.

Millepora dichotoma can be found in various regions, including the Republic of 🇲🇺 Mauritius, the 🌊 Red Sea, and the Indo-West Pacific. These benthic-dwelling corals are typically found at depths ranging from 0.2 to 3 meters.

As carnivorous suspension feeders, Millepora dichotoma's polyps capture plankton and detritus from the surrounding waters and process their intake in their gastrovascular cavity.

Reproduction in Millepora dichotoma takes place between April and May, although the presence of gametes may continue into June. Synchronized release of gametes facilitates external fertilization, with male gametes being broadcast slightly before females release their eggs to increase the chances of successful reproduction. Multiple distinct periods of gamete release occur during the multi-month reproduction period. Fertilized gametes disperse with currents and eventually settle on the seafloor, where they establish new colonies or contribute to existing ones. After the planktonic stage, the polyps settle, adhere to hard substrates, establish symbiotic relationships with zooxanthellae, and develop calcareous skeletons.

Currently, Millepora dichotoma is not at risk of extinction. However, human activities pose threats to their well-being. Damage can occur due to human interaction such as walking, snorkeling, and diving around these corals. Fragmentation of colonies can lead to structural changes, transitioning from more delicate forms, like lace-like structures, to thicker and less fragile forms, such as box-work ones. Areas with human-induced nutrient additions have observed lower numbers of Millepora dichotoma over extended periods. Similar to other coral species supported by symbiotic zooxanthellae, Millepora dichotoma exhibits bleaching events in response to rising ocean temperatures.