YOU SAID:
The hippocampus is jumping on the bus
INTO JAPANESE
海馬がバスに飛び乗っている
BACK INTO ENGLISH
The hippocampus is jumping on the bus.
INTO JAPANESE
海馬はバスに飛び乗っています。
BACK INTO ENGLISH
The hippocampus is jumping on the bus.
That didn't even make that much sense in English.