It would be sharks. They outlived dinosaurs!
Harriet, a giant Galapagos Land tortoise & the world's oldest living creature, will be 179 on Nov. 15. http://www.mirror.co.uk/news/top-stories/2005/10/19/exclusive-the-oldest-creature-on-earth-115875-16265479/
The largest and heaviest living creature on earth is the blue whale.
I believe the biggest living creature that scientists know of right now is the Blue Whale.
possibly plankton
Walking is the oldest. Riding (or being pulled by) an animal is the second oldest. The oldest mode not requiring the energy of a living creature (other than to steer) is sailing.
The Bristlestone Pine is the oldest not largest, it is estamted that the oldest living one on earth at the moment (Methuseslah) is 4,767 years old.
The oldest-living human is currently Jamaica's Violet Brown, who is 117.
Every living creature on earth responds to the messages implicit in the play of light and color.
The first living things on earth were microbes, tiny one-celled creatures.
Blue Whale
Many think that some bacteria may have been the first to orbit the Earth.
Nothing. There is no living creature in earth that is 30 times the size of a blue whale. Blue whales are the largest living things on Earth.