The vaquita is a small porpoise species found only in the northern part of the Gulf of California in Mexico. It is the world's rarest marine mammal, with fewer than 30 individuals estimated to remain. Vaquitas are known for their distinctive dark rings around their eyes and their small size, typically reaching about 4 to 5 feet in length. The primary threat to the vaquita is entanglement in illegal fishing nets used for catching totoaba, a fish whose swim bladder is highly valued in traditional Chinese medicine. Conservation efforts are ongoing to protect the vaquita and its habitat, but the species remains critically endangered.