TankBud

Coco worm

Protula bispiralis

Also known as Hard Tube Coco Worm, Hard-Tube Feather Duster, Red Fan Worm

SaltwaterInvertebrate

Coco worm (Protula bispiralis)
Seascapeza · CC BY-SA 3.0

Care at a glance

Temperature
75–81°F
24–27°C
pH
8.1–8.4
Adult size
5.1 in
13 cm
Minimum tank
20 gal
75 L
Temperament
Peaceful
Social behavior
Solitary
Swim level
Bottom
Diet
Filter feeder
Difficulty
Medium
Breeding
No record
Rarity
Rare
Reef safe
Reef safe
Family
Serpulidae
Origin
Indo-West Pacific reefs

Overview

The coco worm is a peaceful filter feeder for a reef tank, but it is demanding to keep. Most sources rate it for intermediate to experienced keepers rather than beginners.

Did you know

A young coco worm starts out with a simple, two-lobed crown. It develops the tight spiral of up to 80 radioles per side only as it matures. The coiled fan sold under this name is just an adult wearing a more elaborate version of every juvenile's crown.

Caring for the coco worm

A coco worm needs a well-established tank of at least 20 gal (75 L), with a rock and gravel substrate. It needs strong, stable water circulation to deliver its food. Never lift it out of the water upside down or let its tube drain dry, and keep handling to an absolute minimum.

Keep the water at 75 to 81°F (24 to 27°C) and a pH of 8.1 to 8.4. Hold calcium, alkalinity and magnesium at reef-tank levels, because it draws heavily on calcium and alkalinity to extend its tube. A coco worm that cannot build tube fast enough will stall and decline.

The coco worm is a filter feeder, so feed it fresh or preserved phytoplankton every other day at minimum. Release the food into the current rather than squirting it onto the crown, which will just make the worm retract.

It is peaceful and reef safe with corals, fish and other invertebrates. Watch for coral banded shrimp, arrow crabs, wrasses, angelfish and butterflyfish, which may pick at the exposed crown.

Good to know

Protula bispiralis is a tube-building polychaete in the family Serpulidae, distinct from the leathery-tubed feather dusters of the family Sabellidae. It secretes a hard, white, calcareous tube up to 20 cm long, rather than a soft one of mud and mucus. Its adult crown forms a tight spiral of three whorls. Unlike many calcareous tube worms, it has no operculum, the hard plug some relatives use to seal the tube opening. That lack is part of why it is so sensitive to rough handling and to being lifted from the water.

In the wild

Coco worms live on current-swept reef slopes and rubble zones across the Indo-West Pacific. They cement their tubes to rock or dead coral.

Common questions

What size tank does a coco worm need?

A coco worm needs at least 20 gal (75 L). It spends most of its time in the bottom.

What temperature and pH does a coco worm need?

A coco worm is comfortable at 75–81°F (24–27°C) with a pH of 8.1–8.4.

What does a coco worm eat?

A coco worm is a filter feeder. Feed it fresh or preserved phytoplankton at least every other day, released into the current.

How big does a coco worm get?

An adult coco worm reaches about 5.1 in (13 cm).

Related species