In 2–3 sentences, summarize the information in this paragraph.
What are nudibranch? Only some of the most colorful sea creatures on Earth! These marine mollusks boast a variety of unique shapes and colors, and they live anywhere in the world's oceans, from the tropics to Antarctica. There are many different types of nudibranchs, some no longer than an inch, and some as long as two feet! Some use toxic appendages to defend themselves, while others use camouflage. Some even make their own chemicals to keep predators at bay. Why do nudibranchs have these defenses? Because they are naked! Nudibranch means "naked gills," so named for their soft bodies and their exposed gills, which sit atop their backs. While common to the ocean, these unusual creatures can be spotted on underwater dives.