The second part of our series on clean up crew (CUC) for the biactive habitat opens with a focus on our somewhat slimier friends – worms! There are an astonishing variety of worms on the planet, and they all have their own ecological niches and functions. The number of species commercially available, however, is somewhat smaller – thankfully!
So what sort of worms should we be adding to our habitats, and what benefits do they bring?
The sort of worm often found in your garden after a rainy night, and the sort that blackbirds are usually hunting in leaf litter! Large bodied, the Lumbricus and associated species make great reptile and amphibian food, but don’t usually thrive at the higher temperatures of a terrarium habitat. In a more temperate setup or in an extensive outdoor habitat they will probably do well, but not great for an indoor setup.
Of most use in the terrarium are the compost worms, which make their home in warm, damp rotting vegetation and other detritus, converting it all into a nice rich mulm that plants love. In the terrarium, this means that they make a meal of shed skin, faeces, leaf litter, surplus food – in fact, anything that decomposes is grist to their mill. Some people are concerned that these worms (sometimes called tiger worms) are toxic; certainly, when stressed they can exude a foul tasting substance that makes most predators spit them out rather than eat them. As they eat rotting as opposed to already rotted (and thus fairly inert) material, this exudate can be quite nasty depending on what particular items they have been feeding on; in the confines of a terrarium, however, everything is pretty innocuous and unlikely to cause a problem.
The two species you are most likely to come across are Eisenia fetida, which is the one most usually called the tiger worm and the one that has the nasty taste, and Dendrobaena veneta. Both are originally found in Europe, but their adaptability has made them an invasive organism across various areas of the globe. As they feed on rotting vegetation they are most usually found in the top few layers of soil, searching for anything organic to turn into a meal. They lay eggs in the deeper layers of substrate, and once their numbers build up they are quite capable of processing even quite large deposits left behind by snakes and lizards.
White worms (Enchytraeus albidus)
Popular as a cultured fish food, these are tiny, thread-like worms that like it warm, reproduce freely and help to break down waste products in the terrarium. Although they resemble nematodes, they are actually segmented like tiny earthworms. They don’t like too much heat and avoid light completely, but will live in the higher layers of your substrate and reproduce readily.
Grindal worms (Enchytraeus buchholzi)
Another one usually cultured to feed fish, they are a smaller version of the white worm. Their use in the bioactive terrarium lies in the fact that they can tolerate higher temperatures and more variable humidity than their (fractionally) larger cousin. In the wild they can be found in wet meadows and disturbed roadsides, but are easily cultured at home and can be regularly added to process biological waste.
Mealworms (Tenebrio molitor)
More suited to an arid setup, mealworms are notorious for their ability to eat absolutely anything. A pest of grain stores that is now found worldwide, mealworms are the larvae of a darkling beetle that are more usually sold as a reptile and bird food source.