The correct answer is rapids and waterfalls.
Rapids refers to the segments of streams with extensively vigorous currents, various obstacles, and steps in their streambeds. A waterfall refers to a vertical drop in a stream bed. Both are the locations of vigorous erosion.
The rapids are generally produced where the resilient bedrock limits a stream to a narrow channel and forces an enhancement in the velocity of water.
On the other hand, waterfalls are produced where the fast-flowing water negotiates a geologic contact amid the more resilient and less resistant layers of rock, or through a fault, which has analogized distinct kinds of rocks. Or it can be said that waterfalls usually produce at the end of a series of rapids.
Crayfish are invertebrates which means they don't have a backbone. They are also arthropods, which means that they have a protective exoskeleton on the outside of their body. Other arthropods include insects, spiders, and centipedes. Crayfish continually shed their exoskeleton and regrow a new one. During this transition is when they are most vulnerable to predators because they aren't protected by their outer shell.
Crayfish are found all over the world in many different freshwater environments, such as rivers, creeks, springs, and swamps. But this doesn't necessarily mean that you will be able to find them. They are somewhat cryptic because they dig out homes for themselves under rocks and blend in well with their environment. Crayfish will ardently defend this dwelling against intruders using their strong front claws
All elements are made of "atoms", and an atom is made up from 3 basic particles: Electrons are particles with a negative charge :)
Autosomes. The somatic chromosomes are referred to as autosomes.
