Researchers Discovered the Self Defense Mechanism of Water Fleas Against Animals and Carnivorous Plants

The masters of adaptability are water fleas. Researchers from the Technical University of Darmstadt, Albert-Ludwigs-Universität Freiburg, and Ruhr-Universität Bochum (RUB) have shown that they can protect themselves mostly against carnivorous plants but also against mammals.

Self-defense of water fleas

(Photo : Nicole Geri/Unsplash)

They demonstrated that when the aquatic plant Utricularia is present, water fleas travel more slowly and grow lateral spines (bladderworts).

Both defenses appear to make it more challenging for the carnivorous plant to capture them in its trap.

The research team, led by Dr. Sebastian Kruppert, Dr. Martin Horstmann, and Professor Ralph Tollrian from RUB, along with Dr. Simon Poppinga from the Technical University of Darmstadt and Dr.

Thomas Speck from the Freiburg Botanical Garden describes their findings in the International Journal of Molecular Sciences, which will be available online on June 9, 2022.

It was simple to grow the clonal line with the label "04". The researchers gave it the moniker S04 due of its closeness to the Schalke 04 football stadium.

In the lab, the researcher initially divided S04 and the aquatic plant using a tiny grid.

In this way, they made sure the animals couldn't consume the plant or come in contact with it directly, but they could still detect the predator's presence thanks to chemical messages.

Under those circumstances, water fleas developed longer appendages on their carapace and were smaller.

These behavioral modifications and physical changes were successful. The scientists evaluated how frequently animals that had been exposed to the herb vs those that had grown up without it were eaten.

The latter was actually consumed less frequently. Sebastian Kruppert comes to the conclusion that "this suggests that the activatable adaptations are essentially defenses against the plant.

According to Martin Horstmann, "We infer that the appendages allowed the water fleas to grow broader than the width of the suction trap openings," as per ScienceDaily.

Since the water fleas with defenses are also thinner, the water stream may presumably flow through them more readily.

The traps are of varying sizes, but at least the smaller traps can no longer eat the critters.

Water fleas

Any member of the class Branchiopoda, a broad group of around 450 species of crustaceans found worldwide, is a water flea, as per Britannica.

Although a few variants can be found in coastal areas, the majority are found in freshwater habitats.

The most well-known genus is Daphnia, which is common in ponds and streams in North America and Europe.

The average length of a water flea is between 0.2 and 3.0 millimeters (0.01 and 0.12 inches), making it a minuscule creature.

A bivalve carapace covering all or nearly all of the trunk and abdomen is attached to a distinct head that bears antennae.

The predatory giant Leptodora, whose carapace is reduced to a tiny brood sac and grows as long as 18 mm, is an exception.

The majority of species move through the water by making strong strokes with their antennae; in certain species, the repeated strokes create a distinctive hopping and sinking motion.

With the exception of a few predatory varieties, water fleas consume minute organic matter particles that they filter from the water using specialized thoracic limbs.

Fish consume them after that. For instance, practically all commercial fish in the Great Lakes of North America feed certain water fleas as their main source of nutrition.