Spaghetti worms

One aspect of the aquarium hobby that keeps me interested, even after all these years, is the fantastic array of marine life that can and will end up in your tank over time. Every time we place a new coral, fish, live food, or even piece of live rock in the tank, there is a chance we’ve introduced a new invertebrate–or a food source for an invertebrate that has been otherwise laying low.

One of the most mysterious of these hitchhiking invertebrates you may find in your aquarium is the spaghetti worm.

What is a spaghetti worm?

The spaghetti worm is a segmented polychaete relative of the bristle worm and feather duster worm often found in reef tank aquariums. These worms live inside a hard, cylindrical tube that they make, and they get their name from the long, stringy feeding tentacles that extend beyond the tube to catch food particles.

DietOmnivore (whatever they can catch, including detritus)
Size5-6 in. or 12.7-15.2 cm fully grown
Body structureFleshy, translucent, and mucus-like tentacles and a body that is hidden in a hard, tubular shell
Mean of reproductionSexual reproduction and swarming
FoodDetritus, plankton, diatoms, etc.
PredatorsPolychaete-eating fish, crabs, or other invertebrates
Dangerous or problematic?No

What is the Spaghetti worm’s natural habitat?

Spaghetti worms are commonly found in the Atlantic Ocean, from Northern Brazil, Central America up through the Florida Keys. They are generally found in sandy regions and live at that transitions between the reef rock and sandbeds.

Once introduced to an aquarium, you may see Spaghetti worms on the sandy substrate, rocks, or even on the aquarium glass.

What do Spaghetti worms eat and how?

Spaghetti worms use their long, filamentous feeding tentacles to catch and feed upon floating organisms in the water column, including plankton, diatoms, and even detritus. Of course, in your home aquarium, they will also eat any commercial foods they capture.

Spaghetti worms are segmented worms, like bristleworms. But unlike bristleworms, the Spaghetti worm has specialized feeding tentacles that help it catch and eat food right from the water column. The tentacles have grooves that are lined with hair-like structures called cilia. These cilia help spaghetti worms collect and move food towards their mouth, which is generally hidden inside the tube.

When particles are captured that are too large for the cilia to move on their own, the polychaete worm can use the larger tentacle-like an arm to drag the particle towards the mouth.

How do they get in your reef tank?

The most common way for Spaghetti worms to be introduced into your saltwater tank is when you add live rock, live sand, or coral to your tank that has one or more worms or larvae in it. Generally speaking, this process is considered to be accidental. However, when the feeding tentacles are retracted within the tube, it can be hard to see them.

This is commonly and casually referred to as ‘hitchhiking’ by the aquarium community. The practice of adding live rock actually encourages this sort of proliferation of micro and macro fauna; although copepods, amphipods, and coralline algae are generally the more sought-after species, while spaghetti worms bristle worms and aiptasia anemones are more commonly considered hitchhiking pests.

Aquacultured rocks ‘made’ in pest-free environments is now becoming much more popular due to efforts to preserve our reefs and prevent the introduction of unwanted invertebrates into our tanks.

Learn more about Live Rock Hitchhikers here.

Are they good or bad for a reef tank?

Spaghetti worms remove food particles from the water column that, if left unconsumed, would contribute to the harmful production of ammonia, which is a beneficial service for a reef tank. However, if they are located close to corals or other sensitive invertebrates, the constant presence of the feeding tentacles may stress and damage those corals. Therefore, their existence in a reef tank is neither good nor bad. It sort of depends on the context.

The presence of a plague-proportion number of spaghetti worms is potentially an indication that overfeeding the tank is a primary problem, as is also the case when bristle worms become problematic.

In addition to any objective valuation of their merit or harm, many people simply don’t like the look of them. They may choose to try to remove or eliminate them from the tank, even when there is no apparent detrimental issue.

How do you get rid of spaghetti worms?

There are three primary ways to get rid of spaghetti worms:

  1. Physically remove them from the rock or sand by digging them out or chipping off the rock they are attached to, with a hammer and chisel. A screwdriver can work as a chisel if you don’t have one. Most reef rock is easily broken up that way
  2. Dousing them with a super-concentrated solution of calcium hydroxide…aka. kalkwasser…aka. Joe’s Juice (marketed specifically aiptasia and majano anemone removal) is another way to rid your tank of the pest AND give it a boost of stony coral-forming calcium. Just be careful not to drip the paste on anything you don’t want to chemically burn–which means you should be sure to shut off your pumps, too.
  3. Introduce a natrual spaghetti worm predator into your tank and let them take care of business naturally (and get a little healthier while they do it).

What eats Spaghetti worms?

The Spaghetti worm is not a particularly exotic creature, nor do they need a predator with a selective palate to eliminate them. They are a segmented polychaete worm, so the animals that eat other polychaete worms will generally also eat Spaghetti worms. Reef safe wrasses, like the Six-line wrasse or Melanurus wrasse, Sand-sifting fishes like the Diamond Goby, Arrow crabs, and Sand-sifting starfish will likely get the job done, too.

Just keep in mind that if you’re using a biological method to control a biological pest, the solution is natural, perhaps enjoyable to watch, but is often times maddeningly inefficient and/or slow. The animals may take their time. You never know.

Conclusion

The Spaghetti Worm is a mysterious and cryptic invertebrate that may find its way into your tank. If it does, don’t worry right away. They don’t usually cause problems unless they are too close to a sensitive coral. Then, hopefully, you’ll enjoy seeing the miracle of life and competition on a reef in your very own saltwater tank. But if they aren’t your cup of tea, there are options you can employ to evict your unwelcome housemate.

After reading all this, are you worried about them? Or ready to observe and handle if you have to? Please leave a comment and let me know what you think.

What to read next

Check out these other important articles to gain a better perspective on all the invertebrates in a saltwater aquarium

Reef safe starfish

Reef safe shrimp

Clean up crew

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