The Order Nudibranchia comprises a group of soft-bodied, marine gastropod mollusks commonly known as sea slugs. Nudibranchs are noted for their bright colors, intricate patterns, and striking forms, which often serve as warnings to predators of their toxicity or unpalatability. Unlike many other mollusks, they lack a protective shell in their adult form and have exposed gills on their dorsal surface. Nudibranchs are mostly carnivorous, feeding on sponges, hydroids, and other small invertebrates, and some can sequester toxins or stinging cells from their prey for defense. Found in oceans worldwide, they are important members of marine ecosystems and popular subjects for underwater photography due to their vivid appearance.