Mammals can maintain a constant body temperature.

Animal experiments are necessary for the advancement of science, but there are also ethical issues.

He is learning about the handling of experimental animals.

Roundworms are an important part of the soil and contribute greatly to the health and fertility of the soil.

He is a world-renowned zoologist.

My pet is a dog.

Gender identity refers to the gender that each individual recognizes themselves as.

He engaged in an extravehicular activity from the spaceship.

He is undergoing training for extravehicular activity.

The mayor issued a curfew at night due to an emergency.