I agree that it should be better written. I assure you that this slug is 100% animal. The fact that it can use chloroplasts doesn't change its kingdom. It made for an interesting title, but it also made for a false title. It's like when people call macroalgae a plant. It annoys me. I assure you macroalgae is from the kingdom Protista and if you disagree, well then you're wrong.
"This is the first time that multicellar animals have been able to produce chlorophyll," Pierce told LiveScience.