The biggest animal in the ocean, and possibly the largest animal ever to live on Earth, is the blue whale. The maximum recorded weight for a 98-foot blue whale exceeded 209 tons. Longer whales, up to 110 feet, have been seen but not weighed.
While there are several dinosaurs that might have exceeded the blue whale in length, none are thought to have been as massive. Estimates based on incomplete skeletal remains suggest that an unnamed species of Titanosaur may have been 130 feet long, but its weight is estimated at less than 85 tons. While weighing a great deal less than a blue whale, there is a species of tape worm that is nearly as long. It is called the whale tapeworm, and it can grow to lengths of over 98 feet.