Figure. Left top - Side view of the head and brachial crown of M. agassizii. Arrow points to the tentacle base neatly enveloped by the lateral membrane of arm IV. Photograph by David Shale. Right top - Ventral view of Mastigoteuthis sp. hanging in the water just above the ocean floor, submersible photograph, Hawaiian waters. The arrow points to the place where the tentacle emerges from the tentacular sheath of the left arm IV. Photograph modified from Young, et al. (1999), courtesy of the Hawaii Undersea Research Laboratory. Bottom - Dorsal view of a portion of a ventral arm (arm IV) of M. agassizii with the tentacle (white) mostly hidden within the tentacular sheath. The entire length of the tentacle apparently can be held within the tentacular sheath. Photograph by David Shale. Views of M. agassizii were photographed in a shipboard aquarium by David Shale on an NSF cruise with Marsh Youngbluth, Harbor Branch Oceanographic Institution, N.E. Atlantic waters. The brilliant red color in both images has been reduced in Photoshop to accentuate detail. © David Shale