Sea animals are 'les animaux marins' in French.
sea vixon
A sea otter is 'une loutre de mer' in French.
Ocean in French is "Ocean, or you can use Sea in French "Mer". .
"aucuns animaux"
sea shells are coquillages in French. For the purpose of a meal, they are called 'fruits de mer' on the menu.
mammifères marins
mer verte
Une hippocampe
monstre marin
"zoo animals" is "animaux du zoo" or "animaux du parc zoologique" in French.
A sea nymph is 'une nymphe de l'océan / une nymphe marine' in French.
"un animal, des animaux"