A cross sea is a sea state with two wave systems travelling at oblique angles.
Caterpillars have as many as 4,000 muscles in their body.
Caterpillars have six pairs of simple eyes that can see changes in light but not clear images.
Giraffe can never sleep more than one hour at a time.
Lasers can get trapped in a waterfall.
There are 41 countries that recognize sign language as an official language.
Liberia, Myanmar, and the United States are only three countries in the world that don't use the metric system.
Australia is the only continent in the world without an active volcano.