The word vaquita means 'little cow' in Spanish, but they don't look much like cows. They have a small, rounded grey body, a tiny snout, and big dark patches around their eyes and mouth that look a bit like makeup. They are gentle and shy. They never come close to boats and almost never jump out of the water.
Vaquitas live in a part of the Gulf of California that is incredibly warm and salty - much warmer than most porpoises like. Scientists think they have adapted to it over millions of years. They eat small fish and squid that they find by clicking sounds and listening to the echoes, like a built-in sonar.
There are only a few dozen vaquitas left in the wild. They have been hurt by fishing nets meant for other fish, getting tangled up by accident. Mexico has banned that kind of fishing in the vaquita's area and is working with scientists from around the world to protect them.
Every year a team of researchers takes a boat out to look for vaquitas and count them. They have to be very quiet, watch carefully, and wait. Sometimes they only see a few. But each one they find is a sign that this tiny porpoise might still have a future.