Mammals Like Us! Ancestors of gray whales once lived on land. Over millions of years, they returned to the water and adapted to life in that habitat. They may look like fish, but whales are mammals, just like you. First look closely at these pictures. Think about what you know about mammals. What clues do you see that tell you that whales really are mammals? Click on each picture to enlarge. Find out what we think Find out what we think Find out what we think Facebook Pinterest Twitter © 1997 – 2019 Journey North. All rights reserved.