Vandmændene = "the water men"? weird.
Ay, I was expecting 'mermaid'.
I was expecting mermen.
To be fair, "the fish of jelly" isn't much less weird, lol.
Det er hvad det er :-)
Maybe it's like 'man of war'
Just came to the comments section because I was sure someone had probably found it weird, too :)
Hvor mange gange som helst jeg lytter til audioen, jeg hører vand i stedet af vandet :^\
Why this sentence rejects the singular form?
Assuming you mean "The jellyfish is..." then it's because the Danish can only mean the plural. If it were singular then it would be "Vandmanden".
If you meant it the other way around, then it's because of the "are" in the English sentence which means it has to be plural.
So the singular in danish is "Vandmanden"?
And I look up and the plural form of jellyfish in english is jellyfish, this plus your explanation about the plural/singular form in danish explains things for me.
Can this not also be "The jellyfish swim in the water" ?
Yes. Because this is referring to the plural - it says 'the jellyfish [do] swim in the water' (as in, they do). I reported it.
If we had put 'the jellyfish swims in the water', I could understand it being marked wrong, but not without the 's'.