Do animals have desires? Is it even possible to actually ask such a question? I mean... duh
I'd like to say something though. Plants can stretch their roots deeper down the ground in search for water. Let's say there's an underground body of water, a plant could dig the roots deep enough to access that water. Would that count as desire? Neh, plants have no brains, and wouldn't be able to have emotions. They're like machines. They do stuff, but they don't have the desire to. They're just programed to do it (through DNA). The same would go for jellyfish, I guess. They don't have hearts, brains or nerve systems... they just are.
What makes us different from other animals? Well, we're smarter than they are, and we're the dominant species on earth. You don't mess with humanity.
The animals that are most like humans are worth more. Because we can connect with our own kind easier than with... bugs, for examples. Therefore, species that resembles human beings in whatever way will always be considered more important than other.