It's a happy Mother's Day for endangered right whales

For marine biologists at the New England Aquarium, it's a super-sized Mother's Day.

Scientists at the Boston-based center say 17 new North Atlantic right whale calves have recently been born, adding to one of the most endangered whale populations on the planet.

Experts say only about 500 of the mammals classified as "critically endangered" are left on Earth. The Aquarium says the new births are a special cause for celebration because right whales historically have had a low reproductive rate.

The whale mothers gave birth in waters near the border of Florida and Georgia—their primary winter habitat—and they recently arrived in New England with their calves in tow. Six pairs of mothers and calves have been spotted feeding on plankton in Cape Cod Bay.