Acrophobia is the fear of heights. Most people are afraid of heights to some degree, especially when there is nothing to stop them from falling, like the cliff edge in the picture.
Arachnophobia is a fear of spiders and other arachnids, like scorpions. Someone who is arachnophobic may get a panic attack simply from being somewhere they think there are spiders, like when they see cobwebs.
Ophidiophobia or ophiophobia is a fear of snakes. Many people are scared of snakes because snakes are actually quite dangerous and should be treated with caution, but they do not have a phobia of snakes. People who are ophidiophobic are irrationally afraid of snakes, even just in pictures or on television where there is no real threat.