A walk along the seashore at low tide reveals colonies of barnacles stuck to every hard surface. These crustaceans are related to lobsters, crabs, and shrimp.
A shrimp-like barnacle larva ready to settle down sticks its head to an object with its own superglue, then builds up calcium protective plates. The barnacle remains closed up inside, except when it filters food from the water with its fringed feet.
At least a million years ago, our ancestors discovered cooking. But what could they do with the leftovers? Only in the last 400 years have we developed the means to cool things down.
Cooling's not just for food, though. As you plunge below zero, some materials begin to conduct electricity with no resistance. And as you near absolute zero (cold's lower limit), atoms turn weird.
Salamanders and newts lead basic amphibian lives, both in and out of the water. The egg and larval stages take place in the water, while adult lives often play out on land, except at breeding time. Newts are especially terrestrial.
One exception is the axolotl, a salamander that retains its larval gills and fins — and watery lifestyle — its whole life.
Stand long enough on an ocean beach, and you’ll see changes in water level. Thanks to gravity from the moon and the sun and Earth’s own motion, you’ll usually witness two high tides and low tides within a lunar day.
Delve a little deeper into how the relative motion of the Earth, moon, and sun push and pull to create the tides.
Travel into mysterious environments where earthly formations first take shape under the ground. Discover how caves form and what grows inside them, including popcorn, flowstone, and the better-known stalactites and stalagmites. Year after year, these fragile cave deposits develop very slowly.More...
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