The vaquita has the most restricted range of any marine cetacean, as they are endemic to the norther

Thevaquita has the most restricted range of any marine cetacean, as they are endemic to the northern end of the Gulf of California.  They have evolved to live in shallow, murky water, sometimes so shallow that their backs protrude from the water.  Unlike many other marine animals, they can also cope with the rapid and extreme temperature changes that can occur in shallow water.