Bristle worms
Polychaeta
Earthworm relatives that sometimes resemble flowers
Bristle worms are a large group of amazing creatures that belong to the Annelid phylum – the same phylum that our most common earthworms belong to. The vast majority of bristle worms live in the sea, some species are attached to the bottom, and some are free-swimming in the water. Some of those that live on the bottom live in tubes and look like flowers, with coloured tentacles. They range in length, from less than a millimetre to several metres long, depending on the species. The body is divided into several different segments, each with bristles. The bristles are used to help the worm move.
Bristle worms are found in every ocean on earth. A few species live in freshwater or in humid environments on land. In total, there are more than 10,000 species of bristle worms, divided into 24 orders. In Swedish waters there are some 500 species, most of which live along the west coast.
A group of beautiful bristle worms called christmas tree worms, living in coral reefs.
Photo: Nick-Hobgood-CC-BY-SA
An illustration of different species of bristle worms, by the biologist and artist Ernst Haeckel in the early 1900's.
The sand worm is common in Sweden, and lives buried in the sand. It eats tiny organic matter among the grains of sand, and poops out the sand remains - creating these piles you can find along sandy shorelines.
Photo: Auguste-Le-Roux-CC-BY
A tropical bristle worm with long, dense bristles.
Photo: Philippe-Bourjon-CC-BY-SA
This bristle worm species can be found on many places on Earth. It builds tubes of sand and mud to live in.
Photo: Thomas-Valdemarsen-CC-BY-SA
The giant beard worm can grow up to 3 meters in height. It lives in colonies, in the extreme environments close to hydrothermal vents, with hot water and high contents of sulfide.
This bristle worm lives in deep seabeds, eating bacteria from the surface of methane ice.
The sandcastle worm lives in colonies and builds tubes of sand, creating durable reefs.
Bristle worms in the Hyalinoecia genus, builds transparent tubes that looks like straws. The worm brings its tube when it crawls on the sea floor.
Photo: Rickard-Zerpe-CC-BY
The sea mouse is a hairy bristle worm living on sandy sea floors.
Photo: MichaelMaggs-CC-BY-SA
Some species of bristle worms reproduce by budding, where they let go of pieces of themselves which grow into fertile, free-living individuals of the same worm. The fertile forms are called epitokes.
Photo: Megan-McCuller-CC-BY-SA
Sphaerodoropsis philippi is a species of bristle worm, with round, knob-shaped outgrowths. The photo shows a female carrying eggs.
Photo: Arne-Nygren-Sjöfartsmuseet-Akvariet-Göteborg-CC-BY-SA
Turning its mouth inside out
Bristle worms come in many different shapes and forms. They are partly adapted to their different habitats, and partly to the way they eat. Some species are predators and have developed eyes. Others are scavengers or herbivores, or filter food from the water.
Some species of bristle worms have a crown of tentacles with which they both capture food and breathe. Other species have so-called palps, which are used to identify food particles. There are species of bristle worms that turn their mouths inside out in order to catch prey.
A tube-dwelling bristle worm with its tentacles sticking out of its tube.
Photo: Victor-Micallef-CC-BY-SA
The sandcastle worm's tentacles sticking out of the sand tube.
Photo: Fred-Hayes-CC-BY-SA
A bristle worm species from the north Atlantic ocean, with small tentacles.
Photo: Hans-Hillewaert-CC-BY-SA
The Orange thread-gilled worm's long, spaghetti-like tentacles.
Photo: Peter-Southwood-CC-BY-SA
The gossamer worm lives swimming in the free water, sending out a yellow light.
Photo: uwe-kils-CC-BY-SA
Acanthicolepis asperrima belongs to a group of bristle worms with scales on their backs.
Photo: Arne-Nygren-Sjöfartsmuseet-Akvariet-Göteborg-CC-BY-SA
This short, compressed worm is called mud owl, and lives in muddy seabeds with its head pointing down.
Photo: Andrea-Bonifazi-CC-BY-SA
May cause injury to people
Stepping on a bristle worm so that the bristles penetrate the skin can cause severe pain. However, the bristles are not venomous. But there are a few species of bristle worms that can bite and inject a venom. Although, you have to be allergic for the venom to be dangerous. Around the islands of Samoa and Fiji, there is a species of bristle worm that is caught and eaten as a delicacy.
The fireworm has venomous bristles, which can be very painful if they get under your skin.
Close-up on the bristles of at bristle worm.
Photo: Auckland-Museum-Collections-CC-BY
The bobbit worm is a ferocious predator that lives buried in the sand, waiting to drag down any passing prey.
Photo: Rickard-Zerpe-CC-BY-SA
A bristle worm with strong, sharp jaws.
Photo: Alexander-Semenov-CC-BY.
The palolo worm is a species of bristle worm, eaten as a delicacy in Southeast Asia and the Pacific Islands.
Photo: Joko-Pamungkas-CC-BY
This large worm is called the gaebul, which is eaten in South Korea and China.