Translation:Are there many animals swimming in the North Sea?
Does the Dutch "dieren" have any implication of land animals? because in English fish are not generally referred to as animals (it's not wrong, it just sounds weird), so I translated this as "creatures" and was marked wrong.
Fish are animals. If an animal lives in the water that does not mean that it is no longer an animal.
Just like animals dieren does not distinguish between those that live on the land and those that live in the water.
Creatures would generally best be translated to wezens in Dutch.