What animals are potentially approvable by ethics committee for animal studies?

All animals are potentially approvable including Homo sapiens sapiens; however, the nature of the experiment and the reason of the experiment are going to be scrutinized. Doing science for the sake of science will get even an earthworm study revoked. Doing anything with medical or life improvement potential goes over well. Good experimental design and a sound hypothesis will determine what is not approved after that it goes in ethics (benefit of study vs harm or discomfort to organism etc etc)