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Bristle Worm Facts (Segmented Worms)

[Kingdom: Animalia] [Phylum: Annelida] [Family: Polychaeta (marine annelid worms)]

The bearded fireworm (Hermodice carunculata) is one of the typical segmented Polychaetes that live around rocky outcrops or sandy substrate on the ocean floor.

This segment describes the main characteristics of the bristle worm species, including what they eat, and how this hairy sea worm invertebrate reproduces.

Bearded Fire Worm Habitat and Distribution

Hermodice carunculata is superabundant in the Mediterranean Sea and in most regions of the tropical Atlantic Ocean, especially:

Pro Tip: You're almost guaranteed to see a bearded fireworm if you go scuba diving in Europe, particularly around the coastlines of Italy.

Most marine annelid species can cope with the rigours of intertidal, saltwater environments. For example, they live around the shallow rock crevices or Posidonia oceanica that grows near the shorelines of most Mediterranean dive sites.

Some bristle worms can survive on wet driftwood as it floats and moves with ocean currents, and various kinds of artificial reef structures (e.g. rubble deposits, harbour infrastructures) at depths approaching forty metres (around 130 feet).

Hermodice Carunculata Characteristics

Being a nocturnal creature means they are seldom seen in daylight (unless you disturb their habitat). The average size of a bearded fireworm's elongated body is fifteen centimetres (6 inches). But, the largest fire worms can grow to thirty centimetres long (12 inches).

In general, annelid morphology is a combination of a head, up to 150 segments (containing their internal organs), an anus, and a single nuchal organ (used in mating and for food detection).

Here's the thing:

Each segment of a bristle worm's body contains twin appendages (parapodia), covered with bristles or tufts (called setae), common features in marine invertebrates.

The largest fire worms tend to have reddish brown, green, or dark grey colouring. Whereas, smaller specimens are usually bright pink with white, pearly flecks for extra camouflage.

What Do Fireworms Eat?

Being nocturnal creatures and a heterotrophic species means annelids need to find food for nourishment. Even so, many of the Polychaete species vary in their actual feeding habits.

Some are natural predators that eat flatworms, small crustaceans, and mollusks. Whereas, others are scavengers that feed on dead or decaying organisms on the ocean floor. In general, the big orange fireworm (H. carunculata) is a meat scavenger.

Bearded Fireworm Facts (Hermodice carunculata)In fact, this voracious predator will feed on, or siphon, almost anything that dies near its habitat.


Their preferred diet is dead or decaying fish (detritus matter), often bigger than they are, and small clams.

Some annelid worms are filter-feeders that eat plankton and most of the different species of zooplankton

Bearded Fireworm Sting

To some, it looks like a pinky-brown, furry sea caterpillar worm (or even a centipede). But, this saltwater fireworm with hairy spikes is one of the animals that are dangerous to humans - especially careless swimmers.

You should avoid touching bearded fire worm bristles. Their white tufts contain a formidable venom which can burn human skin. Plus, they are as sharp and brittle as porcupine quills, albeit much smaller.

This is the important part:

These burning worms puff out their bristles to deter threats or any perceived danger. Despite not being particularly aggressive towards scuba divers, the best advice is not to touch them, especially with bare hands!

Surprisingly, some are capable of piercing human skin. But, you should find pierced or stuck bristles relatively easy to remove and peel away from your skin using strong sticky tape, for example.

Interesting Fact: The largest fireworms have the largest bristles, and in fact they also have jaws with which they can bite. Other dangerous segmented bristle worm species include the red-tipped fireworm (Chloeia viridisis) and the golden fireworm (Chloeia flava).

Why are Bearded Fireworms Called Fire Worms?

You should not be surprised to learn that the bearded fireworm is so-called because of the burning venom from its stinging hairs. If it stings you, the area will feel like it is on fire and usually lasts for several hours.

In fact, severe symptoms of bearded fireworm sting are rare. But, it is not uncommon to suffer with skin irritation, along with:

The hollow spiny hairs snap away from the animal quite easily and they get stuck to human skin. Moreover, they release a neurotoxin which creates the sting and flaming sensation.

Bristle Worm Sting Treatment

First aid for stings from bearded fireworms means first removing the spines from the injured area. Be mindful that the hairs are minutely small and almost transparent.

If you have a scuba diving first aid kit with tweezers, you may be able to remove them individually. Otherwise, use sticky tape to strip them from the skin - similar to skin waxing.

Vinegar, hydro-cortisone cream, or rubbing alcohol may help to reduce the burning sensation. You might also use a topical antibiotic if you suspect infection.

Taking ibuprofen (as directed by the manufacturer) should help to reduce the pain. But, if the wound deteriorates, you should consult a medical expert knowledgeable in marine life and fish spine injuries.

How Do Fire Worms Reproduce?

For the most part, Polychaetes reproduce via asexual reproduction. They divide into two or more pieces to produce a completely new individual. Even so, the parent will remain as a complete organism.

A similar regeneration mechanism also applies if the organism suffers severe damage. For example, some species are able to regenerate from a single segment - even if their head is cut off.

Pro Tip: Marine annelids and polychaetes are pivotal contributors to the food chains in the oceans because these burrowing worms recycle detritus organic material and help to aerate sediment and substrate.

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