The branchial chamber in decapods and some other crustaceans is the area of the body containing the branchiae, or gills.
In shrimp-like decapods, water enters the chamber from the edges of the carapace.
In crab-like decapods, it enters from respiratory channels near the chelipeds.
This crustacean-related article is a stub.
You can help Wikipedia by expanding it.