Limb-use by foraging marine turtles, an evolutionary perspective

Abstract

The use of limbs for foraging is documented in both marine and terrestrial tetrapods. These behaviors were once believed to be less likely in marine tetrapods due to the physical constraints of body plans adapted to locomotion in a fluid environment. Despite these obstacles, ten distinct types of limb-use while foraging have been previously reported in nine marine tetrapod families. Here, we expand the types of limb-use documented in marine turtles and put it in context with the diversity of marine tetrapods currently known to use limbs for foraging. Additionally, we suggest that such behaviors could have occurred in ancestral turtles, and thus, possibly extend the evolutionary timeline of limb-use behavior in marine tetrapods back approximately 70 million years. Through direct observation in situ and crowd-sourcing, we document the range of behaviors across habitats and prey types, suggesting its widespread occurrence. We argue the presence of these behaviors among marine tetrapods may be limited by limb mobility and evolutionary history, rather than foraging ecology or social learning. These behaviors may also be remnant of ancestral forelimb-use that have been maintained due to a semi-aquatic life history.

<i>Callinectes sapidus</i> Rathbun, 1896 (Brachyura: Portunidae): An assessment on its diet and foraging behaviour, Thermaikos Gulf, NW Aegean Sea, Greece: Evidence for ecological and economic impacts

“…Marcelli et al, 2016). Furthermore, photographic material and videos were used on the assessment of foraging behaviour regarding crabs (Krieger et al, 2016) and turtles (Fujii et al, 2018). The authors of the present study applied these methods as well as conventional traps.…”

“…Currently, cameras and other electronic means are considered as important tools of passive monitoring in many cases and behavioural observations are widely used either in terrestrial or aquatic environments, for instance, in conservation assessments (Cairns et al, 2017), behavioural ecology (Fujii et al, 2018) among others. Moreover, the in-depth knowledge and experience of fishers should be further acknowledged and utilized, and wider collaborations should be established among scientists and policy makers (Azzuro et al, 2018).…”

Non‐trophic impacts from white sharks complicate population recovery for sea otters

“…First, reduced juvenile mortality due to the California gillnet ban of 1994 (Lowe et al, ) likely has encouraged stronger juvenile cohorts by boosting juvenile recruitment. Second, as immature sharks have no social learning (e.g., Fujii, McLeish, Brooks, Gaskell, & Houtan, ), and are less experienced in distinguishing targets, juvenile white sharks may simply target the wrong surface prey. Another explanation for the increased shark‐bite mortality in otters is the population growth of white shark prey (pinnipeds, cetaceans), and a corresponding population increase in white sharks.…”

Flipper bone distribution reveals flexible trailing edge in underwater flying marine tetrapods

“…The elbow and wrist joints are restricted in cetaceans and spheniscids, but they are free to move in otariids and chelonioids (Bannasch, ; Cooper, Dawson, et al, ). Otariids use their forelimbs in terrestrial locomotion (Beentjes, ; Berta & Adam, ) while chelonioids use their forelimbs for terrestrial locomotion and prey manipulation (Davenport et al, ; Fujii, McLeish, Brooks, Gaskell, & Van Houtan, ; Wyneken, ). We segmented the flipper margin and the bony tissue within it from digitized radiographs.…”