Mobility of the sea pen Pteroeides spinosum (Ellis, 1764) (Cnidaria: Scleralcionacea: Pennatuloidea)

The sea pen Pteroeides spinosum (Ellis, 1764), belonging to the superfamily Pennatuliodea McFadden, van Ofwegen & Quattrini, 2022, is a little-known anthozoan species well-adapted to inhabit soft bottoms. Similar to other sea pens, it can form aggregations in both infra- and circalittoral zones, significantly enhancing the complexity and biodiversity of these habitats. We present the first in vivo video observation of rolling behaviour of a P. spinosum individual, documented during a Remotely Operated Vehicle (ROV) survey, in the northern Tyrrhenian Sea, at a depth range of 50–58 m. The animal assumed a wheel-like shape, likely by inflating its body with seawater. This led to a rolling motion along the seabed, covering a linear distance of approximately 7 m in just 4 min. The observed mobility of this species adds new information about its behaviour, emphasizing the role of video technology in capturing real-time information.