Aquatic Worms Facts & Information Guide 2023 (Limnodrilus hoffmeisteri)

Aquatic worms, otherwise known as red worms, look much like common earthworms. Their bodies are about two inches long and are segmented, typical for other Oligochaeta members. Although aquatic worms have an average appearance and typically aren’t given a second look, Limnodrilus hoffmeisteri have the ability to make their environment a place where organisms thrive to the best of their potential – the ultimate ecosystem peacekeepers!

Additionally, Lomnidrilus hoffmeisteri able to redistribute sediment, minerals, beneficial bacteria, and oxygen throughout the topmost layers of soil and parts of the water table, as well as directly aiding in denitrification, meaning that they provide critical and invaluable ecosystem services where they’re present. Worms are often misunderstood and viewed negatively, but they truly are critical parts of every ecosystem, be it aquatic or terrestrial. Without them, organic materials would simply build up and soils and water would become toxic.

For something so small, these critters are quite adaptive! Each individual section of their body works independently and can form cysts, if portions of their body are above the waterline, to keep themselves moist and comfortable.

These worms bring a purpose and a little something special to your pond’s ecosystem. Their ability to feed off of organic matter and to keep the soil moving and aerated while they reside in the bottom of your aquatic area make them the perfect pond house guest!

What Do Aquatic Worms Look Like?

Aquatic worms, like most oligochaetes, have long, segmented, tubular bodies that are without limbs or heads. Even though they don’t have heads, they still have a brain and a nervous system that runs throughout their body to control movement through peristalsis. Their body length is typically 25-40 mm long and divided into 55-95 segments, with each segment being able to regenerate when separated from the body.

L. hoffmeisteri looks red at a glance due to the hemoglobin which carries oxygen around throughout the body of the worm. This is why they’re often dubbed as the “red worm.” However, these aquatic worms are different than the red bloodworms that can be found in pond filters. The hemoglobin in L. hoffmeisteri travels throughout the body of the worm through aortic arches; five of these arches work together to keep the blood circulated. These organisms do not have lungs as we do or gills like fish; instead, they breathe through their skin via gas exchange.

Did you know that these aquatic worms can see? They don’t “see” in the same way that we do, because they don’t have eyes; instead, they have simple photoreceptors that help them distinguish between light and dark! They tend to avoid bright light due to the sensitivity of the photoreceptors and typically stay buried in the coarse particles of the soil or sediment, inhabiting darker spaces. This is very similar to the standard Oligochaeta member as they are often found farther underground or at least completely below the soil surface level.

Aquatic Worm Habitats – Where Do They Live?

Aquatic worms can live in a wide variety of habitats, but don’t fare well in completely oxygen-deficient environments. They also have a unique ability to stay alive in saltwater biomes, unlike other aquatic worms who typically stay in freshwater areas.

L. hoffmeisteri thrive in sediments where microorganisms tend to reside, making them benthic dwellers. These worms stay buried under the surface of coarse particles in the bottoms of lakes, ponds, and groundwater with only their tail exposed. These worms are highly adaptable and some have the ability to survive up to 14 days without moisture at times of severe drought.

Although these organisms are not currently at risk of extinction, their freshwater biomes are being threatened due to modification, fragmentation, and destruction of their habitat, as well as invasive species, environmental pollution, and climate change. Freshwater biomes make up 20% of the Earth and it is important that we do what we can to protect them, both for these critically important organisms and for our own survival.

What Do Aquatic Worms Eat? (Aquatic Worm Diet)

Bon appétit! Microorganisms and other organic materials are on the menu for this species of aquatic worm. You can find these organisms in the sediment on the bottom of most aquatic environments. As these creatures eat and migrate throughout the water body, they keep the sediment moving around in the aquatic system, providing more oxygen to the other inhabitants.

On the flip side, Limnodrilus hoffmeisteri find themselves on the tragic end of the food chain where they are food for pretty much anything! With their soft, fleshy bodies and their slower movements, fish and crustaceans take the dominant stance. As such, aquatic worms not only help to move about nutrients and oxygen in the environment, they also serve as a valuable food source for many other creatures.

Are Aquatic Worms Dangerous or Poisonous?

Aquatic worms are not dangerous or poisonous, and in fact provide some pretty critical services to your pond and anywhere else they’re found! These include breaking down organic matter, helping to disperse sediment, beneficial bacteria, dissolved oxygen, and minerals that in turn aids in healthy water quality and makes these things more readily available to plants, and providing a valuable food source for fish, turtles, newts, waterfowl, and other aquatic or semi-aquatic animals.

There has been one known reported case of a man in China whose nasal cavity became infected with small L. hoffmeisteri. The worms were eradicated without complication, but the medical study notes that this infection likely occurred after bathing or swimming in water during the period in which aquatic worms lay eggs. These eggs can float about the water; because of this, it’s exceptionally important that those who work in, bathe in, or swim in fresh or marine water or are pond hobbyists making regular contact with the water and substrate  wash themselves off thoroughly after making contact with the water, particularly if they touched the substrate at the bottom, in the event that eggs got on the skin and could be transferred elsewhere.

This is a very rare occurrence, and easy to avoid by taking appropriate measures. If infection does occur, these worms are easy to kill with proper medical treatment.

The Life Cycle of Aquatic Worms

Aquatic worms are the jack of all trades in the mating realm! They can reproduce both asexually and sexually, which makes reproduction a little more convenient – this is a particular boon considering they are readily eaten by so many other organisms. Aquatic worms are hermaphroditic, meaning that they can utilize both male and female parts or select one or the other to proceed with the mating process.

In terms of asexual reproduction, these organisms will undergo aspects of transverse fission such as budding or fragmentation, by which they detach portions of their own body that then become new worms. By partaking in this style of reproduction, the population can grow starting with fewer individuals and with a shorter development time, and without the risks of genetic mutation that are typically present when small populations must mate and potentially inbreed. The ideal time frame for reproduction to occur for aquatic worms is during the warmer months when food is easier to locate.

With sexual reproduction, the aquatic worm can select to act as the male component or the female component. With reproductive organs for both sexes in segments 10 and 11, it really is just up to the worm for which role they choose to take on. If sexual reproduction occurs, the organism will grow and develop based on the conditions of the environment in which they were created – if conditions are ideal, then growth will speed up and vice versa.

The life span of Limnodrilus hoffmeisteri is between one and two years, which will vary based on the environment they reside in. In very healthy environments, they have been known to live up to 3 years.

How to Attract Aquatic Worms to Ponds – Are They Beneficial?

Aquatic worms are amazing creatures to have in your pond! By having them around, your pond will be well aerated with oxygen for any plants and animals that you have in the aquatic environment. This is interesting (and extremely helpful) because they can survive on very little oxygen. When you have something that helps creates more oxygen out of lower oxygen environments, you open up other realms of possibility for a plethora of flora and fauna! Additionally, aquatic worms help to distribute beneficial bacteria that may otherwise remain trapped in soil sediment, thus helping to improve water quality.

In order to attract aquatic worms to your pond, be sure to keep a layer of sediment and mud in the bottom of your pond to allow them to thrive and feed appropriately. Aquatic worms prefer shallower water a few feet or less in depth, so having a shallow pond margin will ensure their survival.

As an added bonus, providing shallow margins and a rich layer of rich mud to attract aquatic worms is likely to also attract things like newts and turtles, which will in turn feed on the worms and prevent them from becoming too numerous while providing other valuable ecosystem benefits. This may be of particular interest to you if you’re looking to establish or improve upon a wildlife pond!