Cephalopod dermal structures

[1] The vast majority of cephalopod dermal structures have a thin, overlying epidermal layer, though this is often damaged or missing in captured specimens.

It has been speculated that in the live animal the interstitial space is filled with a buoyant fluid (likely an ammonium chloride solution) and acts as a "buoyancy vest".

[1][13][14] It has been proposed that these two species achieve buoyancy by means of the fluid stored in their vacuolate dermal cushions and upper mantle layer.

More specifically, they may be involved in maintaining laminar flow by preventing or delaying boundary layer separation along the mantle.

[1] In the cranchiids Leachia cyclura and Liocranchia reinhardti, the dermal tubercles are not distributed throughout the mantle but arranged in discrete cartilaginous bands.

[1] The very dense tuberculate ridges found on the arms and dorsal mantle of Histioteuthis meleagroteuthis may similarly provide insertion points for muscles, and are probably most important in juvenile animals, which lack well-developed musculature.

In a 1990 study of dermal structures in squid, Clyde F. E. Roper and C. C. Lu wrote that they were "unable to suggest a function" for the tubercles of this species, but that due to their small size and spacing they were unlikely to be involved in buoyancy or locomotion.