Did You Know? | Interesting facts about the world around us.

Posted by Between the Lines • Profile • 10/07/26 at 01:30AM • Curiosity & Discovery • See more by Between the Lines

Did You Know? | Kudos365 Curiosity Series

1. Sharks existed before trees.
Shark-like fishes appeared in Earth's oceans more than 400 million years ago. The earliest known trees appeared tens of millions of years later, during the Devonian Period. Sharks therefore belong to an evolutionary lineage considerably older than forests.

2. Some turtles can absorb oxygen through their rear ends.
Certain freshwater turtles can perform cloacal respiration, absorbing dissolved oxygen through specialized tissues near the cloaca. This adaptation is especially useful when turtles remain underwater for extended periods, including during winter dormancy.

3. Earth's atmosphere extends far beyond what we normally think of as “space.”
The atmosphere becomes progressively thinner rather than ending at a sharp boundary. Traces of Earth's outermost atmospheric region extend thousands of miles into space, although satellites and spacecraft operate comfortably within these extremely sparse upper regions.

4. The world's largest waterfall is underwater.
Between Greenland and Iceland, cold, dense water from the Nordic seas plunges beneath warmer Atlantic water in the Denmark Strait cataract. The enormous underwater descent is several times the height of Venezuela's Angel Falls, although it looks nothing like the waterfalls we see on land.

5. Oxford University is older than the Aztec Empire.
Teaching was taking place at Oxford by 1096, although the university did not spring into existence on a single founding date. The Aztec Empire arose much later, in 1428, when the alliance of Tenochtitlan, Texcoco, and Tlacopan established the political power commonly known today as the Aztec Empire.

6. A teaspoon of neutron-star material would have an extraordinary mass on Earth.
Neutron stars compress more mass than the Sun into a sphere only about the size of a city. Matter under those conditions is so dense that a teaspoon-sized amount, if it could somehow be brought intact to Earth, would have a mass of roughly a billion tons. The comparison is illustrative—the material could not simply exist here in the same state.

7. The Canary Islands were not named after canary birds.
The islands' name traces back to the Latin Canariae Insulae, associated with dogs. The familiar yellow canary bird was named after the islands where its wild ancestors were found—not the other way around.

8. The longest-lived vertebrates known to science are Greenland sharks.
Researchers studying Greenland sharks have estimated that exceptionally old individuals can live for several centuries, with one large female estimated at roughly 400 years old, though with a substantial range of uncertainty. That means some Greenland sharks alive today may have been born centuries before the United States existed.

Sometimes the familiar world becomes much more interesting when we look a little closer: Explore. Discover. Learn.