DOI: 10.5061/dryad.0rxwdbs0b
title: Video recordings of polynoid (Annelida) swimming and crawling

description: Annelids are predominantly found along the seafloor, but over time have
 colonised a vast diversity of habitats, such as the water column, where
 different modes of locomotion are necessary. Yet, little is known about
 their potential muscular adaptation to the continuously swimming required
 in the water column. The musculature and motility were examined for five
 scale worm species of Polynoidae (Aphroditiformia, Annelida) found in
 shallow waters, deep sea and caves that exhibit crawling, occasional
 swimming or continuous swimming, respectively. Their parapodial
 musculature was reconstructed using microCT and computational 3D analyses
 and the muscular functions interpreted from video recordings of their
 locomotion. Since most benthic annelids are able to swim for short
 distances using body and parapodial muscle movements, suitable musculature
 for swimming and a pelagic lifestyle is already present. Our results also
 indicate that rather than rearrangements or addition of muscles, a shift
 to a pelagic lifestyle is mainly accompanied by structural loss of muscle
 bundles and density, as well as elongation of extrinsic dorsal and ventral
 parapodial muscles. In addition, our study documents clear differences in
 locomotion and muscular arrangement among closely related annelids with
 different lifestyles as well as points to myoanatomical adaptations for
 accessing the water column.
description: All video recordings were taken within 24 hours from species
 sampling. High-speed recordings of <em>P.iliffei</em>’s
 locomotion were taken using a monochrome camera (Sanstreak Edgertronic
 SC1) with different lens configurations: 2x microscope Olympus objective
 with adapter and extension tubes and Nikon 50 mm f/1.8lens with 12 mm or
 20 mm extension tubes) at 900 fps. Extension tubes were used to achieve
 proper focus with the microscope objectives and to reduce the minimum
 focus distance with the other objectives.- Brightfield illumination was
 obtained by use of LED light sources and a large-diameter (200 mm)
 condenser lens. Locomotion of <em>G. jameensis</em> and
 <em>H. imbricata</em> were recorded using a Panasonic HC-VX980
 Camcorder respectively at 50 and 25 fps. Locomotion recordings did not
 include <em>M. longipalpa</em> nor
 <em>Branchipolynoe </em>sp. due to lack of live specimens.
 <em>Pelagomacellicephala iliffei</em> was recorded in a square
 plexiglass water tank 18x15centimetres, whereas <em>H.
 imbricata</em> was recorded in a 250mLplastic algae culturing
 vessel. <em>Gesiella jameensis</em> was recorded in a 9 cm
 petri dish with black velvet background. All containers were filled with
 their respective ambient cave or seawater and having adequate space for
 free swimming. Selected sequences were digitized and analysed using the
 software DLTdv8 (Hedrick, 2008).
description: Locomotion of <em>Pelagomacellicephala iliffei
 </em>in lab setup, swimming, and closeup
 Locomotion of <em>Harmothoe imbricata </em>in lab
 setup, crawling, and swimming Locomotion of
 <em>Gesiella jameensis </em>in lab setup, swimming and
 crawling and in live recordings from cave system, swimming
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