Although trematodes are often too small to be seen with the naked eye, they live very interesting lives. These worm parasites feed on various animals in order to develop and reproduce, which biologists metaphorically call “hosts.” This is why they always use snails as an intermediate host, while their ultimate host varies from frog to human.
This complex life cycle entails risks. If trematodes do not find a specific host, reproduction will not occur. Therefore, these parasites have developed tricks to increase the chance of success. leucochloridium paradoxum, For example, cares In unfortunate amber snails there is an amazing sight: their eyes begin to pulsate. This shimmering movement proves irresistible to the birds, the next host. The bird eats the infected snail – to the benefit of our parasite, which can continue its life cycle.
Deformed frog
We see a similar story with Ribeiroia-parasite. Hundreds of larvae of this parasite emerge from an infected snail after the horn every day in search of unsuspecting tadpoles. The parasite burrows its way through the skin and disrupts development: the tadpole grows into a multi-legged frog. The result is a mutilated frog as a defenseless victim of a heron, the parasite’s next host. Like pulsating eyes, this deformity increases the chance of the next victim becoming infected – perhaps these parasites are the world’s best puppeteers?
Gyrodactylus salaris He steals the show in a different way. Instead of manipulating the host, it hacks into its reproductive process. Offspring are produced within 24 hours because they are born pregnant and therefore give birth immediately after birth (to a pregnant daughter). So when researchers open a worm, they find another worm inside, with another worm inside. Doesn’t this remind you of Russian matryoshka dolls? The European salmon knew this. Since the appearance of this parasite in Norway in 1970, salmon populations have completely collapsed. Millions of euros have already been spent to eradicate this parasite by treating rivers with the heavy toxin rotenone. However, the parasite continues to spread, including through humans. So fishermen should chemically disinfect their fishing rods, or…put them in a sauna for an hour. Fortunately, there is no shortage of saunas in the Far North.
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