Bearded Fireworm – Hermodice carunculata

The Bearded Fireworm, also known simply as Fireworm, is a species in the class of the Polychaete. Caution should be exercised when diving. When the bristles of Hermodice carunculata penetrate into the skin they cause a burning pain that can last for days.


The Bearded Fireworm has an elongated body that can have more than 100 segments. The segments are clearly delineated by light streaks. The front can be identified by the prostomium, which has an intense yellowish to orange colour and resembles the gills. It is located on the four front segments.

The colouring of Hermodice carunculata ranges from greenish, brownish to reddish.

On the sides of the segments there are tufts of bristles alternately projecting upwards and sideways. Red-orange excesses can be seen on the bristles. These are the gills.

The Fireworm reaches a maximum length of 35cm.

Habitat and Distribution

Hermodice carunculata lives on rocky ground, corals and sea grass meadows, in depths up to 50m. When diving in the Canary Islands, it is very common, so there is no dive without it.

It has also been assumed that its spread extends across the Caribbean, the Gulf of Mexico, the Red Sea, the Indo-Pacific, the Mediterranean Sea, the coasts of West Africa to the Canary Islands. According to a study from 2011, however, morphological differences between the specimens of the Caribbean, the Mediterranean and those in the eastern Atlantic were discovered. This means that there are probably different subspecies.


The Bearded Fireworm lives solitary. It is both day and night active.

Hermodice carunculata is an active hunter who feeds on crustaceans, Anthozoa and echinoderms. In addition, one can observe from time to time how groups of Fireworms feed on carrion.


The Bearded Fireworm can reproduce both sexually and asexually. Asexual reproduction occurs when individuals undergo fragmentation and decompose the body into one or more parts that regenerate to form head, tail, or both, and grow into new individuals.

The most famous feature of the Fireworm is the bioluminescence during sexual activity. The spawning is usually 2-5 days after full moon.

Special Features

bearded fireworm Hermodice fluorescence carunculata diving canary islands canaries atlantic ocean
Fluorescent Fireworm (Hermodice carunculata)

Hermodice carunculata carries a bacterium that causes coral bleaching in the case of stony corals. When the bacterium is transferred to the coral, white spots are formed on the coral, spreading out over three weeks, completely fading and killing the coral. Temperatures of less than 20 degrees, the bacterium only protrudes in the body of the Fireworm.

Furthermore, the Bearded Fireworm is one of the strongest fluorescent species I have seen so far.

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