Chromodoris willani, a vibrant sea slug, exhibits striking blue and white coloration with black spots. Found in the Indo-Pacific, it thrives in coral reefs. This nudibranch features gills and rhinophores with a unique white edging, and exhibits a chemical defense mechanism through toxins acquired from its diet.

Chromodoris willani is primarily found in the Indo-Pacific region. Its geographical distribution includes countries such as Indonesia, Papua New Guinea, the Philippines, and parts of the Great Barrier Reef in Australia. It is also seen in areas like the Solomon Islands and Fiji.

Chromodoris willani inhabits tropical marine environments. It is typically found in coral reefs and rocky substrates in shallow waters, often at depths ranging from 5 to 30 meters. The water temperature in these regions is warm, usually between 24°C to 28°C (75°F to 82°F).

This species is a type of sea slug, specifically a nudibranch, which is part of the larger group of marine gastropod mollusks. Chromodoris willani plays a role in the coral reef ecosystem as a grazer. It feeds primarily on sponges, using its radula to scrape off sponge tissue, which helps control sponge populations and maintain the balance of the reef ecosystem.