HomeSea Life CreaturesMarine AnimalsInvertebrates › Annelid Worms

Marine Annelids Facts and Characteristics

[Kingdom: Animalia] [Clade: Bilateria] [Superphylum: Lophotrochozoa] [Phylum: Annelida]

The broad phylum Annelida contains around 22,000 different species. The group includes several thousand marine annelids (segmented worms) that live in various aquatic environments.

This segment describes the main characteristics of annelida, including what they eat and how they reproduce, with a list of the most common annelid species (soft-bodied marine worms).

Five Key Characteristics of Phylum Annelida

Besides their segmentation (known as metamerism in zoology), almost all polychaete worms share several traits, such as:

Despite several revisions, most research refers to Annelida subdivisions as being Polychaetes (marine organisms), oligochaetes (e.g. earthworms), and certain species of leeches.

Polychaetes are bristle worms that live in various types of oceanic environments. There are about twelve thousand (12,000) Polychaete species still in existence.

Here's the thing:

By and large, basic annelid morphology is a combination of a head, multiple segments (that contain their internal organs), an anus located at the end of the digestive tract (gut), and a single nuchal organ (used in mating and for food detection).

Most polychaetes (poly meaning many and chaetae meaning hair) also have a pair of unjointed lateral outgrowths (parapodia) on each segment - limbs used for locomotion.

What Do Annelids 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. Others are filter-feeders that eat plankton and most of the different species of zooplankton.

How Do Annelids 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.

Annelid Worms Species List

Alitta Succinea

Alvinella Pompejana

Bearded Fireworm

The bearded fireworm (Hermodice carunculata) is a fascinating creature that looks like a pinky-brown furry caterpillar (pictured below).

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

Bobbit Worm

Christmas Tree Worm

Christmas tree worms are sedentary tube-building polychaetes of the phylum annelida, and live on large stony brain corals and Porites compressa (finger coral).

This segment contains facts and information about Spirobranchus giganteus, including where they thrive best, what they eat, and how these invertebrate tube-dwellers breed and reproduce.

Cirratulus Cirratus


Eurythoe Complanata

Feather Duster Worms

In general, feather duster worms (Sabellidae) are comparatively large segmented sedentary marine tube worms. Its common name of 'feather duster' refers to its giant size fan-like coloured crown tentacles situated on each side of its head.

Hypania Invalida

Parchment Tube Worm

Polydora Ciliata


Streblospio Gynobranchiata

Divers also enjoyed reading about...