Annelids

Phylum Annelida

The phylum Annelida includes earthworms, polychaete worms, oligochaetes, and leeches.  Worms in this phylum are primarily characterized by having segmented bodies (some worms have more conspicuous segments than others).  Except for leeches, all annelids also have hair-like projections, called setae, coming from their body.  The worms we will address here are all marine annelids, and are either in the class polychaeta or oligochaeta.

Polychaeta – A polychaete is a worm that has many setae projecting off of its body (“poly” meaning many).  Most segments on a polychaete have parapodia, or paddle-like feet, which are used for movement and other functions such as pumping water through burrows.  The picture below is an example of parapodia on a polychaete with setae protruding coming from them.

Parapodia

Oligochaeta – An oligochaete is a worm that has fewer and simpler setae projecting out of the body wall.  Earthworms are terrestrial oligochaetes.  Estuarine oligochaetes are much smaller and generally less than a centimeter long.  A high power microscope is often needed to look at the setae of an oligochaete in order to identify it.

Clam worm O

Alitta succinea

Characteristics:

Polychaete; head has four large eyes, four pairs of tentacles, and one pair of long palps

Characteristics:

Polychaete; head has four large eyes, four pairs of tentacles, and one pair of long palps

Range:

Atlantic and Pacific coasts of the U.S.

Size:

Up to 1.5in (3.5cm) in length

Habitat:

Estuaries, tidal creeks, marsh platform, sand and mud

Fun Fact:

Worms in this family are highly preferred and sought after by shorebirds

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Fan worm H

Hydroides dianthus

Characteristics:
Polychaete; lives in calcium carbonate tube; tentacles protrude for feeding; tube closes with an operculum

Characteristics:
Polychaete; lives in calcium carbonate tube; tentacles protrude for feeding; tube closes with an operculum
Range:
Atlantic coast of the U.S., south through the West Indies
Size:
Less than 0.5in (1cm) in length
Habitat:
Hard surface in estuaries, such as oyster reefs
Fun Fact:
Known as a fouling organism because of its ability to cover hard surfaces, especially oysters
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Capitellidae D

Characteristics:
A polychaete family; bodies tapered at end; loosely coiled; shorter setae, need microscope to identify to species level

Characteristics:
A polychaete family; bodies tapered at end; loosely coiled; shorter setae, need microscope to identify to species level
Range:
Atlantic and Pacific coasts of the U.S., the Gulf of Mexico
Size:
Less than 0.5in (1cm) in length
Habitat:
Estuarine flats, marsh platform, tidal creek bottoms
Fun Fact:
Will reproduce during times of environmental stress
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Monopylephorus rubroniveus D

Characteristics:
Oligochaete; body with numerous segments similar to earthworm; red gut and white coelomocytes (cells)

Characteristics:
Oligochaete; body with numerous segments similar to earthworm; red gut and white coelomocytes (cells)
Range:
Atlantic and Pacific coasts of the U.S.
Size:
Less than 0.5in (1cm) in length
Habitat:
Salt marsh, tidal creeks, primarily intertidal
Fun Fact:
Very tolerant of stress and pollution, found in areas with high levels of contaminants and hypoxia; candy cane appearance
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Plumed worm C

Diopatra cuprea

Characteristics:
Polychaete; lives in tube with items attached to it; five antennae; body with branchiae (like gills) behind the head

Characteristics:
Polychaete; lives in tube with items attached to it; five antennae; body with branchiae (like gills) behind the head
Range:
Atlantic coast of the U.S., and the Gulf of Mexico
Size:
Up to 5in (12cm) in length
Habitat:
Mud and sand flats, primarily intertidal
Fun Fact:
Decorated tube (pictured above) is home for other small animals and plants which are sometimes eaten by the worm
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Streblospio benedicti H

Characteristics:
Polychaete; head with four eyes and four tentacles; red-brown body; each segment with small parapodia

Characteristics:
Polychaete; head with four eyes and four tentacles; red-brown body; each segment with small parapodia
Range:
Atlantic and Pacific coasts of the U.S.
Size:
Less than 0.5in (1cm) in length
Habitat:
Estuaries, tidal creeks, marsh platform
Fun Fact:
Feeding typically happens by the tentacles sweeping the surface of the mud to capture fine particles and detritus
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