Swim bladder measurements of Cyclothone species from the BATHYPELAGIC cruise to the Northeast Atlantic Ocean

This dataset contains the values of swim bladder length, height, width, angle, volume, equivalent spherical radius and aspect ratio in Cyclothone spp. measured during the Bathypelagic cruise (from 24th May to 23rd June 2018). Samples were obtained with MOCNESS-1 m² (with a 0.2 mm mesh size) zooplankton net during day and night hauls carried out from the surface to 1800 m depth. MOCNESS samples were preserved in 5% buffered formalin. Standard length (SL, ±0.01 mm) and swim bladder (Sw, ±0.001 mm) on each specimen were measured at the land-based laboratory. A stereo microscope fitted with an ocular micrometer was used to obtain the swim bladder length height, width, and swim bladder angle (θ). The longitudinal axis was set as the reference line for the angle (θ =0) with positive values over the reference line. Swim bladder volumes were approximated using the formula for a prolate spheroid, the equivalent spherical radius was estimated following the equation of Strasberg (1953) and the aspect ratio was calculated as the ratio of the height to the longitudinal semi-axis.