Hallasan was isolated from the mainland for a long time and its species were able to become unique and different from mainland species. The elevation of the mountain causes various plant species to live there. The mountain became a habitat for plants that live in low elevation and plants that live in high elevation. 50 or more unique species live in Jeju Island, especially in high elevation area in Hallasan. Various animal species also live on the mountain. Because of the geography of the mountain, the same species evolved in different ways after thousands of years. Just like plant species, animal species originally living in cold and hot climates use the mountain as their habitat. There are a total of 160 bird species that use Hallasan as a habitat. Only 19 species are considered as a natural monument and protected by the government. Ravens are commonly seen in the hiking trail. A total of 3,315 insect species live on the mountain. 254 spider species also live there. A study found that spider habitat is concentrated more on the north side of the mountain. Ticks live on the mountain and gave lots of damage to Jeju residents a long time ago. The damage caused by ticks is still continuing these days. Six tick species give damage to domestic animals.