Using process similar to ultrasound.
Experts report dolphins might be able to detect a developing fetus in a pregnant women using echolocation—a process where dolphins emit sounds to figure out their environment and hear the sounds that return. This echolocation works similarly to (guess what!)—an ultrasound. An Emory University neuroscientist said it's "extremely plausible" a dolphin can detect a fetus. Just the latest neat trick from our marine mammalian cousins, who display a host of other mind-boggling behaviors, from the ability to locate mines under the ocean floor to gang-rape and infanticide.