Locomotory activity and feeding strategy of the hadal munnopsid isopod Rectisura cf. herculea (Crustacea: Asellota) in the Japan Trench

Abstract

SUMMARYBenthic fauna in the hadal zone (6500-11,000m) rely on maintaining sufficient locomotory activity to exploit a low, patchy and uniquely distributed food supply while exposed to high pressure, low temperatures and responding to predator-prey interactions. Very little is currently known about the locomotory capabilities of hadal fauna. In situ video footage of the isopod Rectisura cf. herculea ( , respectively. These data suggest no significant reduction in locomotory capability despite the extreme depths in which they inhabit. These observations also revealed the isopod to be a bait-attending and aggregative species and suggest that it may not be obligatorily selecting infaunal food sources as previously thought.

Trilobite ‘pelotons’: possible hydrodynamic drag effects between leading and following trilobites in trilobite queues

“…Jamieson et al . () also reported a single individual R. herculea with a high size‐specific speed of 0.33 cms −1 BL −1 relative to the mean 0.19 cms −1 BL −1 . This particular specimen accelerated to 1.2 cms −1 as an aversion response in the presence of a fish, as shown in Figure (Jamieson et al .…”

“…5 min; or an anaerobic threshold speed, sustainable for between 20 and 60 min (see foregoing discussion on the ‘power profile’) for R. herculea (but not a maximum explosive speed, for which Jamieson et al . () reported considerably higher backward jump escape speeds). From this aversion response speed, we approximated a scaled corresponding maximal sustainable aerobic power, or anaerobic threshold, speed for T. chopini .…”

“…This particular specimen accelerated to 1.2 cms −1 as an aversion response in the presence of a fish, as shown in Figure (Jamieson et al . ). We consider this aversion response to be within mid‐range sustainable capacities described as a maximal sustainable aerobic speed, sustainable for c .…”

“…We used data from Jamieson et al . (), illustrated in Figure , for R . herculea , a living crustacean with a body length between 2.5 and 5 times that of T. chopini , to derive an approximate range of speeds for T. chopini for a range of body lengths (BL).…”

“… Estimated maximal sustainable walking speed trilobites of varying body length, scaled according to aversion response size‐specific speed of 0.33 cms −1 BL −1 from Jamieson et al . () for the extant crustacean, R. herculea . …”