[Hydromedusae] In some medusae, a cone-shaped thickening of the subumbrellar mesoglea projecting centrally downwards into the subumbrellar cavity, to the end of which the manubrium is attached, the radial canals running down the peduncle to the manubrium at its end. Variable in shape and size (e.g., long and narrow in Eutima gracilis; large and pyramidal in Bougainvillia macloviana; very short in Proboscidactyla stellata).

Alternative form for Gastric peduncle : Gastric peduncle.