Stuff You Should Know Short Stuff: Why do kangaroos hop?
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May 6, 2026 Why kangaroos are the only marsupials that hop. A look at their odd body plan, rainforest ancestors, and the evolutionary path from climbing to bounding. It also gets into the oversized fourth toe, springy tendons, and balancing tail that make their movement so unusual.
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How Joeys Finish Developing In The Pouch
- Kangaroos are marsupials, so much of a joey’s development happens in the pouch rather than in the womb.
- Josh says the joey latches onto a nipple that swells to three times its size, effectively locking the baby in place while it develops.
Why Kangaroos Evolved From Climbers To Hoppers
- Kangaroos became hoppers after Australia shifted from rainforest to dry grassland, changing how they needed to move.
- Chuck says fossils from 25 million years ago suggest early kangaroos were climbers, and Josh notes the crucial fourth toe evolved before hopping itself.
The Fourth Toe Powers Kangaroo Hopping
- Kangaroos hop because their oversized fourth toe lines up with the leg bones and channels force efficiently.
- Josh says powerful elastic tendons act like springs, storing energy on landing and releasing it to launch jumps up to 25 feet forward.