Why Do Some Animals Get Gigantic?

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Occasionally, internal or external factors change, allowing certain animals to become giant versions of themselves.

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To learn more, start your googling with these keywords:
Spiracles: External respiratory openings on insects
Carboniferous Period: The time period from 359-299 million years ago when the Earth’s oxygen levels increased rapidly.
Square-Cube Law: A mathematical principle that describes the relationship between area and volume.
Buoyancy: An upward force exerted by a fluid that opposes the weight of an immersed object.
Phytoplankton: Microscopic plants eaten by krill and other zooplankton.
Baleen: A filter-feeding system inside the mouth of some whales.


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Script Writer: David Goldenberg (@dgoldenberg)
Script Editor: Emily Elert (@eelert)
Video Illustrator: Ever Salazar (@eversalazar)
Video Director: Kate Yoshida (@KateYoshida)
Video Narrator: Kate Yoshida (@KateYoshida)
With Contributions From: Henry Reich, Alex Reich, Peter Reich
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Kaiser, A., et al. (2007). Increase in tracheal investment with beetle size supports hypothesis of oxygen limitation on insect gigantism. 13198-13203. PNAS. Retrieved from:

Sander, P. Christian, et al. (2011). Biology of the sauropod dinosaurs:the evolution of gigantism. Biological Reviews. 86(1): 117–155. Retrieved from:

Taylor, M and Weder, M. (2013). Why sauropods had long necks; and why giraffes have short necks. PeerJ 1:e36. Retrieved from:

Verberk, W. and Bilton, D. (2011). Can Oxygen Set Thermal Limits in an Insect and Drive Gigantism? PLOS One. 6(7): e22610. Retrieved from:

Slater, G., Goldbogen, J., Pyenson, N. (2017). Independent evolution of baleen whale gigantism linked to Plio-Pleistocene ocean dynamics. Proceedings of the Royal Society B. 284: 20170546. Retrieved from: