The Bigfin Reef Squid (Sepioteuthis lessoniana) is a widely distributed cephalopod species found in tropical and subtropical shallow waters, particularly around coral reefs in regions such as Japan, Southeast Asia, Australia, and across the Indian and Pacific Oceans. It is named for its long, slender body and large, fin-like extensions that run along both sides, giving it a graceful appearance as it swims.

This squid is known for its ability to rapidly change color, a feature made possible by specialized pigment cells in its skin called chromatophores. This ability is used for camouflage, communication, and defense. Bigfin reef squid feed primarily on small fish, crustaceans, and other small marine organisms, and are known for their speed and precision in hunting.

Due to its tender texture and delicious flavor, the Bigfin Reef Squid holds high culinary value throughout Asia, especially in countries like Japan, Korea, China, and Taiwan. It is commonly prepared as sashimi, grilled, boiled, or deep-fried (as tempura). Its flavor is clean and delicate, and when fresh, it is ideal for raw consumption, offering a chewy yet silky mouthfeel.

In addition to its culinary popularity, the species is also important in aquaculture due to its fast growth and strong reproductive ability. Its economic and ecological significance makes it a valuable resource in both fisheries and the seafood market.