The cuttlefish has an interesting method of locomotion. Their tentacles aren’t appendages they use for swimming, it is their lateral fins that surround the external mantle cavity that produces an undulating movement that streamlines the water around them. This mechanism has been observed to provide balance to the cuttlefish, as they would be able to correct their positioning almost 360 degrees around them. 

 

Not only do they have external fins that continuously move, but they also have a faster method of transportation, in which they utilize expelling water from their mantle cavity through a siphon. This acts as a form of “jet propulsion” that can quickly be used to push the cuttlefish out of harm's way or to quickly move in on prey. 

 

From a study observing captured cuttlefish (Denton, Gilpin-Brown 1961), the light was found to have a profound effect on the buoyancy of the cuttlefish. This particular study is relevant to cuttlefish motility because, like most aquatic species, buoyancy is key in maintaining depth, controlling hypoxic effects from rapid ascension, and motility. Cuttlefish have the ability to control the volume of gas in which they contain in their bodies by siphoning in and out seawater. Changing the volume proportions of water to gas inside of their bodies creates a controllable mechanism for regulating buoyancy in cuttlefish. 

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How does light affect buoyancy?

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Cuttlefish behavior was analyzed in different lighting conditions, after sufficient feeding. When light exposure increased directly into the tank containing the cuttlefish, they immediately released pressure built up inside of their mantle cavity and buried themselves deep into the substrate below them. They then would emerge after some time the light was dimmed. While it seems to be a preference for light, this study is important in showing how cuttlefish use their mechanisms of controlling their own buoyancy when faced with ill-suited light conditions. This information also correlates to a cuttlefish’s habitat, in which they prefer to dwell in deeper regions of the ocean.