Measuring the Greenland shark’s growth rate is challenging because individuals are rarely recaptured. However, one shark tagged in 1936 had only grown 2.3 inches when it reappeared 16 years later.

The following June, Pinkfong put out a second video, titled Baby Shark Dance, featuring two cute kids performing the dance routine. That clip that inspired the hashtag #BabySharkChallenge - with ...