On the Wings of Angels Sea angels (Clione limacina) are 5 cm-long gastropods whose typical foot orga

On the Wings of Angels

Sea angels (Clione limacina) are 5 cm-long gastropods whose typical foot organ has been modified into a pair of wing-like structures. They are sometimes referred to as pteropods, which literally means ‘winged foot’.

Although they are pelagic (meaning they inhabit the open sea), sea angels need to constantly flap their 'wings’ to stay afloat in the water column, because they are negatively buoyant. 

In a relaxed state, they maintain a slow, rhythmic beating of their wings, but can increase swim speed when stimulated by a disturbance, the presence of a predator, or when hunting.

Video source: Kapr Divers

Reference:Szymik and Satterlie. 2011.