Net Fire Coral

Overview

The Net Fire Coral (Millepora dichotoma) is a colonial hydrozoan that forms complex, calcified structures on tropical reefs. Despite its coral-like appearance, it is more closely related to hydras and possesses powerful stinging cells that can cause painful, burn-like reactions in humans.

Distribution & habitat

This species is primarily found in the Red Sea and across the tropical Indo-Pacific region. It typically inhabits coral reefs, where it attaches to hard substrates. Its growth form is highly influenced by local environmental conditions, such as water depth and turbulence; it may develop into delicate, lace-like structures in calmer, deeper waters or more robust, box-work formations in high-energy environments.

Appearance

Colonies often begin as encrusting layers before developing into intricate, branching, or leaf-like blades. They are typically brown, beige, or yellowish in color, often featuring distinct white tips on their branches. The surface is covered in tiny pores: larger gastropores house feeding polyps, while smaller dactylopores contain the defensive, stinging polyps.

Biology & behavior

Millepora dichotoma relies on a symbiotic relationship with zooxanthellae, which provide nutrients through photosynthesis and contribute to the colony's vibrant coloration. It is also a carnivore, using its specialized polyps to capture plankton and small prey from the water column. The species is capable of both sexual reproduction, involving the release of planktonic medusae, and asexual reproduction through the regeneration of broken fragments.