Optimization of foraging and diet by the piscivorous Othos dentex (Serranidae)

Abstract

The aim of this study was to determine the dietary characteristics and mouth morphology of Othos dentex and to use these data, together with in situ observations of feeding behaviour, to elucidate how foraging and diet are optimized by this piscivorous serranid. Seasonal spear and line fishing over reefs in south-western Australia yielded 426 O. dentex (total length, L , 183-605 mm), among which the stomachs of 95 contained food. The food in the stomachs of 76 fish was sufficiently undigested to be seen to contain, almost invariably, a single fish prey, which was typically identifiable to family and often to species. The prey of O. dentex, which were measured (L ), represented 10 families, of which the Labridae and Pempheridae constituted nearly two-thirds of the prey volume. Two-way crossed analysis of similarities of volumetric data for stomach contents showed that the dietary compositions of the different length classes of O. dentex in the various seasons were significantly related to length class of prey, but not to prey family, length class within the various prey families or season. Furthermore, an inverse (Q-mode) analysis, including one-way analysis of similarities, showed that the patterns in the prey consumed by the different length classes of O. dentex in the various seasons were related more strongly to length class than prey family. The former trend is exemplified in a shade plot, by a marked diagonality of the length classes of prey with increasing predator size. The ingestion of typically a single teleost prey, whose body size increases as that of O. dentex increases, reduces the frequency required for seeking prey, thus saving energy and reducing the potential for intraspecific competition for food. The ability of O. dentex to ingest large prey is facilitated by its possession of a very large gape, prominent recurved teeth, dorsal and independently-moveable eyes, cryptic colouration and effective ambush behaviour. Othos dentex has thus evolved very cost-effective mechanisms for optimizing its foraging and diet.

Trophic ecology of speckled peacock bass Cichla temensis Humboldt 1821 in the middle Negro River, Amazon, Brazil

“…The size of the prey consumed increased with the size of the speckled peacock bass. For most piscivorous fish, the size of the prey consumed usually increases with the size of the predator (French, Platell, Clarke, & Potter, 2017;Juanes et al, 2002). This affirmation is verified in our study and could be attributed to the ability of Cichla of detecting and capturing prey to according to its development, which can be stimulated by an increase in visual acuity with increasing body size (Caves, Sutton, & Johnsen, 2017).…”

“…For most piscivorous fish, the size of the prey consumed usually increases with the size of the predator (French, Platell, Clarke, & Potter, 2017;Juanes et al, 2002). For most piscivorous fish, the size of the prey consumed usually increases with the size of the predator (French, Platell, Clarke, & Potter, 2017;Juanes et al, 2002).…”

Regional differences in the feeding of the ambush predator Neosebastes pandus and comparisons of diets in the Scorpaenidae, Triglidae and Platycephalidae

“…Since N. pandus is a cryptic ambush predator with a relatively large mouth, they are probably able to capture and ingest relatively large prey, even from a small size (Gerking, ; Harmelin‐Vivien & Bouchon, ; Platell & Potter, ). This strategy reduces the frequency of feeding and thus energy expenditure (French et al ., ) and explains why the dietary components contributing to the highest % V also had the highest % F .…”

“…To capture their prey, these fish rely largely on ambush predation (Consoli et al ., ; Motomura et al ., ; Platell & Potter, ), a specialized form of feeding behaviour that relies on camouflage, cryptic behaviour and rapid, selective strikes to capture prey (Curio, ; Gerking, ; Keenleyside, ). This feeding strategy uses little energy, yet is highly effective at catching prey with precision (Coulson et al ., ; French et al ., ; Schultz & Kruschel, ).…”

Diets of reef‐dwelling labrids (Choerodon species) vary with body size, season and habitat: influence of foraging ability, specialization and opportunism

“…The development of a range of multivariate methods (Clarke et al ., ) has greatly enhanced the ability to compare statistically the dietary compositions within and among species and identify the prey taxa that are responsible for any differences (Lek et al ., ; French et al ., ). These contemporary techniques facilitate comparisons between the relative extents to which the dietary composition for a species differs between habitats or environments, changes with increasing body size and responds to any seasonal variation in prey composition (Byron & Link, ; Platell et al ., ; Coulson et al ., ).…”