The use of bioweapons is prohibited by international law.

The study of nekton is an important part of marine biology.

My biological clock is disrupted, and I've been having sleepless nights.

Invasive species can have a major impact on the natural environment.

The American continent is where diverse cultures and nature coexist.

My dream is to live in the United States of America someday.

The whooping crane is an endangered species, and it is difficult to see its beautiful figure.

The American red wolf is one of the endangered species.

My friend came from American Samoa.

My dream is to go to the Northern Mariana Islands.