How do Blackworm reproduce?
F. Mattier"Among the aquatic invertebrates offered at Aquazolla, I have a strong affection for the Blackworm."
Food that fish love (some even call it the "caviar" of fish!), this pretty worm has its own interest in itself. I personally have an aquarium without fish, which is entirely dedicated to it.
The Blackworm is related to our well-known earthworm. Let's say it's a cousin.
His scientific name is Lumbriculus variegatus and it is strictly aquatic.
"Its color is brown-red, but the magnifying glass that sits next to any good aquarium of critters actually reveals a much more complicated anatomy than just a simple 'brown spaghetti'!"
One can then very easily see its "blood" system pulsing like a heart, and a fascinating translucent body, always in internal movement.
In nature, besides serving as food for fish, the Blackworm lives partially buried in the substrate. Head down, it lets its posterior dance in the water, with which it breathes.
"At the slightest alert, he completely sinks into the sand or mud."
It is precisely in the substrate that it finds the organic waste on which it feeds. Like its distant terrestrial cousin, it does not feed directly on the decomposing matter, but rather on the microorganisms that they host.
It is therefore a detritivore, in that it participates in the decomposition of organic "waste."
But it is about its mode of reproduction that this already fascinating worm becomes even more so.
Indeed, its sexual organs have been identified in the laboratory. Its sexual reproduction is therefore perfectly possible.
And yet, although it has been studied in depth for decades in laboratories around the world, no one has ever witnessed a single mating!
'Sexual reproduction is therefore theoretically possible, it may sometimes occur in nature... but no one has ever had proof of it.'
Because, on a daily basis, this worm reproduces by dividing.
It is sometimes said that the earthworm produces two individuals when it is cut. This is absolutely false, only one part survives. So it is just a legend.
But, for the Blackworm, it’s true.
"At certain stages of its life, a part of its body becomes fragile, and it splits in two at the slightest movement of the substrate. The wound, which has been prepared, is then slight, and the two pieces each give rise to a new individual."
When you raise Blackworms in sand like I do, it is enough to gently stir the sand they live in from time to time to softly induce this break and hasten the multiplication of individuals.
And this without sex!
This worm is so fascinating that it has its place in a "creepy-crawly" aquarium, with no fish to make a meal of it!