Prey Size Research Articles

Evaluating the Use of Chemical Weapons for Capturing Prey by a Venomous Mammal, the Greater Slow Loris (Nycticebus coucang).

Few mammals are venomous, including one group of primates-slow (Nycticebus spp.) and pygmy (Xanthonycticebus spp.) lorises. Hypotheses for the evolutionary function of venom in these primates include defense from predators or ectoparasites, communication or competition with conspecifics, and the capture of prey. We tested the prey capture hypothesis in 75 trials with 22 wild-caught greater slow lorises (N. coucang) housed in a rescue center in Java, Indonesia. We experimentally offered the slow lorises arthropod prey items varying in size, escape potential, and toxicity and recorded venom-related and predatory behaviors using live and video observations. The slow lorises visually targeted arthropod prey, approached it quickly and efficiently, and captured it with a manual grasping motion. They rarely performed venom-related behaviors and seemed to do so in a defensive context. The slow lorises exhibited little variation in pre-capture behavior as a function of prey size or escape potential. In response to noxious prey, the slow lorises performed tongue-flicking and other investigative behaviors that indicate they are using chemosensory input to assess prey characteristics. These data suggest it is unlikely that slow lorises use chemical weapons to subdue arthropod prey and may support, instead, a defensive function for slow loris venom.

Temperature alters the predator-prey size relationships and size-selectivity of Southern Ocean fish

A primary response of many marine ectotherms to warming is a reduction in body size, to lower the metabolic costs associated with higher temperatures. The impact of such changes on ecosystem dynamics and stability will depend on the resulting changes to community size-structure, but few studies have investigated how temperature affects the relative size of predators and their prey in natural systems. We utilise >3700 prey size measurements from ten Southern Ocean lanternfish species sampled across >10° of latitude to investigate how temperature influences predator-prey size relationships and size-selective feeding. As temperature increased, we show that predators became closer in size to their prey, which was primarily associated with a decline in predator size and an increase in the relative abundance of intermediate-sized prey. The potential implications of these changes include reduced top-down control of prey populations and a reduction in the diversity of predator-prey interactions. Both of these factors could reduce the stability of community dynamics and ecosystem resistance to perturbations under ocean warming.

Variability in intermediate predator hatching does not alter top-down effects of top predators

Variability in phenological shifts (seasonal changes in biological events) has become more common with climate change. As phenological variability increases due to climatic factors, species interactions within diverse communities can be affected. Shifts in hatching phenology can lead to body size variability that can alter species interactions, especially within and across trophic levels in complex food webs. To understand the effects of hatching phenology and food web complexity on prey communities, we conducted an experiment with ectotherms from ponds by manipulating hatching synchrony of a prey species across three dates and food web complexity. We hypothesized that predation on prey would be highest in the lowest synchrony treatment due to predator satiation effects in high synchrony additions. Food webs with top predators present had the lowest survival rates for prey compared to other food webs. Prey size at metamorphosis was also highest in the top predator food webs, suggesting a thinning effect. Hatching synchrony treatments did not have a significant impact on prey survival or size at metamorphosis except in treatments where intermediate and top predators were absent. Overall, our results show that top-down effects of predators may be enough to suppress the influence of phenological shifts in prey.

Predator-prey interactions across hunting mode, spatial domain size, and habitat complexities.

Predator-prey interactions are a fundamental part of community ecology, yet the relative importance of consumptive and nonconsumptive effects (NCEs) (defined as a risk-induced response that alters prey fitness) has not been resolved. Theory suggests that the emergence and subsequent predominance of consumptive or NCEs depend on the given habitat's complexity as well as predator hunting mode and spatial domain sizes of both predator and prey, but their relative influence on the outcome of predator-prey interactions is unknown. We built agent-based models in NetLogo to simulate predator-prey interactions for three hunting modes-sit-and-wait, sit-and-pursue, and active-while concurrently simulating large versus small spatial domain sizes for both predators and prey. We studied (1) how hunting mode and spatial domain size interact to influence the emergence of consumptive or NCEs and (2) how, when NCEs do dominate, hunting mode and spatial domain separately or additively determine prey shifts in time, space, and habitat use. Our results indicate consumptive effects only dominate for active predators when prey habitat domains overlap completely with the predator's spatial domain and when sit-and-wait and sit-and-pursue predators and their prey both have large spatial domains. Prey are most likely to survive when they shift their time but most frequently shift their habitat. Our paper helps to better understand the underlying mechanisms that drive consumptive or NCEs to be most dominant.

Black Carp Mylopharyngodon piceus (Richardson, 1846) Mouth Gape and Size Preference of a Bivalve Prey

Black carp Mylopharyngodon piceus (Richardson, 1846) have been widely used as biological control of snails in aquaculture and were imported to the United States in the 1970s and 1980s for this purpose. Prior research emphasizes the species’ propensity to control gastropods, but since subsequent escape and establishment of black carp in portions of the Mississippi River Basin, concerns now focus on the numerous endangered and endemic bivalve species upon which black carp may predate. Black carp mouth gape may limit predation on larger bivalves, but bite force is also a factor. We used regression of fish length to mouth gape of wild-caught black carp and compared these results to tank forage size preference trials with bivalve prey Corbicula fluminea clams. Wild-caught black carp ranged from 429 to 1580 mm total length, a size range larger than measured in previous studies. Regression of fish length and mouth gape indicated greater variability among sizes, as expected from wild versus cultured populations. Clam consumption was size-dependent. Black carp commonly engulfed but did not consume the largest clams in tank feeding trials. Shell width was a better predictor of successful consumption than length or height. Predation was restricted at sizes less than the mouth gape of test black carp as observed by individuals engulfing but failing to consume prey. This result indicates that either bite force or the pharyngeal apparatus gape (i.e., the distance between the pharyngeal teeth and keratinous pad) limited successful crushing of engulfed shells. Bivalve predation by black carp is limited by both a fish’s ability to engulf prey and the ability to fracture the shell of larger prey items that cannot be broken or swallowed whole. The results of this research may be used to assess potential prey sizes of wild black carp and anticipated effects of predation on bivalve communities.

Body size mediates trophic interaction strength of novel fish assemblages under climate change.

Ecological similarity plays an important role in biotic interactions. Increased body size similarity of competing species, for example, increases the strength of their biotic interactions. Body sizes of many exothermic species are forecast to be altered under global warming, mediating shifts in existing trophic interactions among species, in particular for species with different thermal niches. Temperate rocky reefs along the southeast coast of Australia are located in a climate warming hotspot and now house a mixture of temperate native fish species and poleward range-extending tropical fishes (vagrants), creating novel species assemblages. Here, we studied the relationship between body size similarity and trophic overlap between individual temperate native and tropical vagrant fishes. Dietary niche overlap between vagrant and native fish species increased as their body sizes converged, based on both stomach content composition (short-term diet), stable isotope analyses (integrated long-term diet) and similarity in consumed prey sizes. We conclude that the warming-induced faster growth rates of tropical range-extending fish species at their cool water ranges will continue to converge their body size towards and strengthen their degree of trophic interactions and dietary overlap with co-occurring native temperate species under increasing ocean warming. The strengthening of these novel competitive interactions is likely to drive changes to temperate food web structures and reshuffle existing species community structures.

What bycatch tells us about the diet of harbor and gray seals and overlap with commercial fishermen

Northwest Atlantic harbor (Phoca vitulina vitulina) and gray (Halichoerus grypus atlantica) seal populations are recovering from early to mid-20th century exploitation, increasing their biological interactions and bycatch in Northeastern US commercial fisheries. We evaluated the seals’ diet composition and compared their prey to commercial catches to assess trophic overlap and potential competition with commercial fisherman target catches. We obtained 148 harbor and 178 gray seal stomach samples from bycatch events that occurred between 2004 and 2018. We learned from the hard part remains that the majority of seals bycaught are young-of-the-year (≤12 months old) that consume a wide breadth of prey across three trophic groups. There was a general dichotomy in extrinsic factors associated with seal diet in which 45% trophic niche separation was explained by non-overlapping harbor and gray seal phenology and pup haul-out locations that are adjacent to active fishing areas. Prey size estimated from fish otoliths and squid beaks recovered from stomach contents showed that gray seals consumed larger prey than harbor seals and prey sizes from both seals showed limited overlap with prey sizes caught by commercial gillnet fishermen. The most important prey to both seals included large (>20 cm) and small (≤20 cm) silver hake (Merluccius bilinearis), (≤40 cm) red hake (Urophycis chuss), gulf stream flounder (Citharichthys arctifrons), medium (21–40 cm) white hake (Urophycis tenuis), and (<50 cm) Atlantic cod (Gadus morhua). Important prey to harbor seals that did not overlap with gray seals were Acadian redfish (Sebastes fasciatus), Atlantic herring (Clupea harengus), longfin (Doryteuthis pealeii), and shortfin squid (Illex illecebrosus). They contrasted with prey important to gray seals that did not overlap with harbor seals: yellowtail flounder (Limanda ferruginea), sand lance (Ammodytes spp.), Urophycis spp., and fourspot flounder (Hippoglossina oblonga). Despite the potential bias associated with opportunistic bycatch sampling, this study demonstrates the importance and value of utilizing carcasses retained from bycatch events, is complimentary to newer methodologies (i.e., DNA meta-barcoding), and fills data gaps in our understanding of the role recovering harbor and gray seal populations have on Northeastern US regional food webs.

Taxonomic relationship does not limit dietary assemblages in fish: an investigation in small freshwater fishes

Abstract Foraging profitability is one of the significant factors affecting habitat selection in fishes. The food habits of the fish species vary seasonally due to the dynamic nature of their environment. For that, the dietary analysis of a fish is essential in the case of fish diversity research. Most of the variations in prey size consumed by piscivores were correlated to the differences in piscivore body size, which morphological constraints can explain. The present study aimed to investigate the ecomorphological assemblage of small indigenous freshwater fish species from smaller lentic freshwater bodies based on a range of morphological traits and evaluate fish assemblages with respect to the feeding guilds. Freshwater ponds around Birbhum district, West Bengal (India) were selected for the collection of fish species, namely Amblypharyngodon mola, Puntius sophore, Esomus danrica, Lepidocephalichthys guntea, Chanda nama, Parambassis lala, Trichogaster fasciata, Anabas testudineus and Glossogobius giuris. Morphometric and gut content analysis were done, and the trophic guild matrix, taxonomic distance matrix, and morphological matrix were calculated. The result showed a strong association between ecomorphological traits and trophic structure, indicating an independent assemblage pattern beyond the taxonomic influence.

High-Voltage Toxin'Roll: Electrostatic Charge Repulsion as a Dynamic Venom Resistance Trait in Pythonid Snakes.

The evolutionary interplay between predator and prey has significantly shaped the development of snake venom, a critical adaptation for subduing prey. This arms race has spurred the diversification of the components of venom and the corresponding emergence of resistance mechanisms in the prey and predators of venomous snakes. Our study investigates the molecular basis of venom resistance in pythons, focusing on electrostatic charge repulsion as a defense against α-neurotoxins binding to the alpha-1 subunit of the postsynaptic nicotinic acetylcholine receptor. Through phylogenetic and bioactivity analyses of orthosteric site sequences from various python species, we explore the prevalence and evolution of amino acid substitutions that confer resistance by electrostatic repulsion, which initially evolved in response to predatory pressure by Naja (cobra) species (which occurs across Africa and Asia). The small African species Python regius retains the two resistance-conferring lysines (positions 189 and 191) of the ancestral Python genus, conferring resistance to sympatric Naja venoms. This differed from the giant African species Python sebae, which has secondarily lost one of these lysines, potentially due to its rapid growth out of the prey size range of sympatric Naja species. In contrast, the two Asian species Python brongersmai (small) and Python bivittatus (giant) share an identical orthosteric site, which exhibits the highest degree of resistance, attributed to three lysine residues in the orthosteric sites. One of these lysines (at orthosteric position 195) evolved in the last common ancestor of these two species, which may reflect an adaptive response to increased predation pressures from the sympatric α-neurotoxic snake-eating genus Ophiophagus (King Cobras) in Asia. All these terrestrial Python species, however, were less neurotoxin-susceptible than pythons in other genera which have evolved under different predatory pressure as: the Asian species Malayopython reticulatus which is arboreal as neonates and juveniles before rapidly reaching sizes as terrestrial adults too large for sympatric Ophiophagus species to consider as prey; and the terrestrial Australian species Aspidites melanocephalus which occupies a niche, devoid of selection pressure from α-neurotoxic predatory snakes. Our findings underline the importance of positive selection in the evolution of venom resistance and suggest a complex evolutionary history involving both conserved traits and secondary evolution. This study enhances our understanding of the molecular adaptations that enable pythons to survive in environments laden with venomous threats and offers insights into the ongoing co-evolution between venomous snakes and their prey.

Trophic niche of a neustonic copepod community sustained by local production in high- and low-salinity summer water masses in the northeastern East China Sea

We investigated the trophic dynamics between neustonic copepod communities and particulate organic matter (POM) sourced from contrasting water masses, i.e., high- and low-salinity areas, within the northeastern East China Sea. The sampling of neustonic copepod communities occurred three times in the summer (June, August, and September) of 2021, and considered the influx of the Yangtze River Diluted Water (YRDW) and the extension of the Tsushima Warm Current (TWC). To examine the relationship between the neustonic copepods and surface POM, we employed stable isotope techniques. Surprisingly, the neustonic copepod community exhibited a reluctance to feed on surface POM. The neustonic copepod community in the YRDW-dominated area in August showed higher δ13C values than those in the TWC-dominated area. The trophic groups within the neustonic copepod population appeared to consume selectively depending on the individual preferred prey sizes and composition. Using the POM from the water masses that affected the food sources consumed by neustonic copepods, we found a strong dependence on prey items originating from the TWC. This result suggests that the marine neustonic copepod community does not rely significantly on food sources derived from riverine freshwater.

Food preference for native and invasive prey in the naive lancehead pitviper

AbstractThe presence of invasive species in the environment can be highly detrimental. The success of these species depends on their interaction with native ones. The prey–predator relationship between invasive and native species can result in biodiversity loss or the introduction of new food items for local predators. Due to its tropical and extensive nature, Brazil is vulnerable to the colonization of invasive species. Snakes are a group of animals that can act as both predators and prey for invasive species. The pitviper Bothrops jararaca is an abundant and widely distributed native species on the Brazilian coast. Based on this, we conducted a study on the feeding preferences of naive B. jararaca juveniles regarding invasive and native prey. We found that this species exhibits a greater preference for native anurans compared to Rana catesbeiana, an invasive amphibian associated with significant environmental impacts. Additionally, the gecko Hemidactylus mabouia, a prey that triggered intense predatory responses from the pitviper, reveals that this species, even with a short period of coexistence with B. jararaca, has established an intense prey–predator relationship. The negative correlation between prey size and feeding interest, guided solely by olfactory cues, adds a layer of complexity to understanding the feeding choices of B. jararaca, providing valuable insights for conservation and environmental management strategies.Abstract in Portuguese is available with online material.

Foraging efficiency of two alpine bird species in central Japan

ABSTRACT Capsule The foraging efficiency of Alpine Accentors Prunella collaris and Japanese Accentors P. rubida is highest on the snow surface in the alpine zone, where they forage for fallen arthropods. Aims To compare the foraging efficiency of two bird species across alpine habitats, including the snow surface, and discuss the impact of changes in snow cover on their foraging behaviour. Methods The foraging efficiency of two alpine bird species, recorded as the number of pecks per unit time, was compared in the alpine zone of Mount Norikura in central Japan, among four habitat types: snow surface, Japanese Stone Pine scrub, alpine tundra and scree. Results In total, respective 45 and 32 foraging sequences of Alpine Accentors and Japanese Accentors were recorded. For both species, foraging efficiency was markedly higher on the snow surface than in other habitats. Conclusion Alpine bird species exhibit high foraging efficiency on the snow surface in the alpine zone, assuming that prey sizes are similar across habitats. With the decreasing amount of remaining snowpack in the alpine zone, due to the general trend of climate change, bird species will likely have a shorter period to efficiently utilize these foraging habitats in the future.

Beyond the kill: The allometry of predation behaviours among large carnivores.

The costs of foraging can be high while also carrying significant risks, especially for consumers feeding at the top of the food chain. To mitigate these risks, many predators supplement active hunting with scavenging and kleptoparasitic behaviours, in some cases specializing in these alternative modes of predation. The factors that drive differential utilization of these tactics from species to species are not well understood. Here, we use an energetics approach to investigate the survival advantages of hunting, scavenging and kleptoparasitism as a function of predator, prey and potential competitor body sizes for terrestrial mammalian carnivores. The results of our framework reveal that predator tactics become more diverse closer to starvation, while the deployment of scavenging and kleptoparasitism is strongly constrained by the ratio of predator to prey body size. Our model accurately predicts a behavioural transition away from hunting towards alternative modes of predation with increasing prey size for predators spanning an order of magnitude in body size, closely matching observational data across a range of species. We then show that this behavioural boundary follows an allometric power-law scaling relationship where the predator size scales with an exponent nearing 3/4 with prey size, meaning that this behavioural switch occurs at relatively larger threshold prey body size for larger carnivores. We suggest that our approach may provide a holistic framework for guiding future observational efforts exploring the diverse array of predator foraging behaviours.

Season, prey availability, sex, and age explain prey size selection in a large solitary carnivore.

Prey selection is a fundamental aspect of ecology that drives evolution and community structure, yet the impact of intraspecific variation on the selection for prey size remains largely unaccounted for in ecological theory. Here, we explored puma (Puma concolor) prey selection across six study sites in North and South America. Our results highlighted the strong influence of season and prey availability on puma prey selection, and the smaller influence of puma age. Pumas in all sites selected smaller prey in warmer seasons following the ungulate birth pulse. Our top models included interaction terms between sex and age, suggesting that males more than females select larger prey as they age, which may reflect experiential learning. When accounting for variable sampling across pumas in our six sites, male and female pumas killed prey of equivalent size, even though males are larger than females, challenging assumptions about this species. Nevertheless, pumas in different study sites selected prey of different sizes, emphasizing that the optimal prey size for pumas is likely context-dependent and affected by prey availability. The mean prey weight across all sites averaged 1.18 times mean puma weight, which was less than predicted as the optimal prey size by energetics and ecological theory (optimal prey = 1.45 puma weight). Our results help refine our understanding of optimal prey for pumas and other solitary carnivores, as well as corroborate recent research emphasizing that carnivore prey selection is impacted not just by energetics but by the effects of diverse ecology.

Bioenergetic modelling of a marine top predator's responses to changes in prey structure.

Determining how animals allocate energy, and how external factors influence this allocation, is crucial to understand species' life history requirements and response to disturbance. This response is driven in part by individuals' energy balance, prey characteristics, foraging behaviour and energy required for essential functions. We developed a bioenergetic model to estimate minimum foraging success rate (FSR), that is, the lowest possible prey capture rate for individuals to obtain the minimum energy intake needed to meet daily metabolic requirements, for female sperm whale (Physeter macrocephalus). The model was based on whales' theoretical energetic requirements using foraging and prey characteristics from animal-borne tags and stomach contents, respectively. We used this model to simulate two prey structure change scenarios: (1) decrease in mean prey size, thus lower prey energy content and (2) decrease in prey size variability, reducing the variability in prey energy content. We estimate the whales need minimum of ~14% FSR to meet their energetic requirements, and energy intake is more sensitive to energy content changes than a decrease in energy variability. To estimate vulnerability to prey structure changes, we evaluated the compensation level required to meet bioenergetic demands. Considering a minimum 14% FSR, whales would need to increase energy intake by 21% (5-35%) and 49% (27-67%) to compensate for a 15% and 30% decrease in energy content, respectively. For a 30% and 50% decrease in energy variability, whales would need to increase energy intake by 13% (0-23%) and 24% (10-35%) to meet energetic demands, respectively. Our model demonstrates how foraging and prey characteristics can be used to estimate impact of changing prey structure in top predator energetics, which can help inform bottom-up effects on marine ecosystems. We showed the importance of considering different FSR in bioenergetics models, as it can have decisive implications on estimates of energy acquired and affect the conclusions about top predator's vulnerability to possible environmental fluctuations.

Diet Composition and Feeding Habits of Fish Larvae of Five Species in the Burullus Lake, Egypt

Feeding habits of fish larvae were analysed in a comparative study of five species (Oreochromis niloticus, O. aureus, Tilapia zilli, Mugil cephalus and Liza ramada) from the Burullus Lake. We investigated the potential influence of larvae size on their feeding and looked for common patterns in larval prey preference. Gut contents of a total of 1068 larvae were examined. The feeding habits of the examined larvae shared some characteristics. As larvae of the five species grew, the preferred prey size and the number and diversity of prey in the gut increased. On the other hand, larval feeding also differed in several aspects, especially differences in the composition of preferred prey items. For Cichlidae larvae, the dominant prey was the rotifer Brachionus plicatilis followed by copepodite stages. For M. cephalus larvae, the copepods Paracalanus sp and Acartia sp were the most important diets, while for L. ramada, decapod larvae were the most important. The Mugilidae larvae consumed significantly larger prey than the cichlid larvae, which could be related to their morphology, especially the mouth size. Ivlev’s selectivity index calculated for larvae showed positive selection for particular prey. In all the species, copepods were the most selected, particularly for Mugillidae larvae, but for Cichlidae larvae, the rotifer Brachionus competed with copepods as a selected prey. This dietary study of fish larvae of these important species is essential for the development of fisheries and can be implemented in further related studies of other areas.

Warming causes contrasting spider behavioural responses by changing their prey size spectra

Warming causes contrasting spider behavioural responses by changing their prey size spectra

A feeding organ the basihyal and thyrohyal tells which size of prey do true baleen whales (Cetacea, Chaeomysticeti) eat

A feeding organ the basihyal and thyrohyal tells which size of prey do true baleen whales (Cetacea, Chaeomysticeti) eat

Trophic Interactions of European Hake Merluccius merluccius (Linnaeus, 1758) in Benthic Communities off the Moroccan Mediterranean Coastline: Seasonal and Ontogenetic Shifts.

The European hake, Merluccius merluccius (Linnaeus, 1758), is one of the most important resources for Mediterranean fisheries. Due to its pivotal role in energy transfer from lower to higher trophic levels, this species is a crucial component of the ecosystem's functioning. The ecological role of Merluccius merluccius, off the Moroccan Mediterranean Sea (southern Alboran Sea), was investigated, exploring seasonal and ontogenetic shifts, geographical variations in prey composition, and feeding strategy. Between November 2020 and July 2022, a total of 402 hake specimens were collected by oceanographic bottom trawl surveys (MEDITS) that were carried out during warm and cold seasons to assess their diet and feeding habits. The sample was analyzed according to fish sizes and seasons, and qualitative/quantitative feeding indices were calculated. The trophic spectrum of Merluccius merluccius included 24 prey items in total, mainly belonging to Osteichthyes (12), Crustacea (10), Cephalopoda (1), and Polychaeta (1), suggesting a generalist behavior of this predator as in numerous regions of the Mediterranean Sea, with several species that occasionally occurs in its diet. In the Moroccan Mediterranean Sea, Osteichthyes proved to be the most important prey item (%IRI = 78.56) among the different zoological groups, followed by Crustacea (%IRI = 16.22). The other food items were occasionally and randomly consumed, and cannibalism was low (0.8%). Hierarchical cluster analysis and nonmetric multidimensional scaling (nMDS) showed different feeding habits of two main groups separated at 60% similarity: small specimens <10 cm TL, primarily feed on zooplanktonic prey, while medium and large specimens hold a diet based on Osteichthyes with crustaceans. Furthermore, a significant positive relationship between hake and fish prey size was confirmed. Seasonally, mesopelagic Osteichthyes were the main food prey in the summer season, while pelagic species were predominant during the autumn. SIMPER analysis revealed that the prey items contributing the most to the differences between seasons and length classes were Engraulis encrasicolus, Micromesistius poutassou, Boops boops, Macroramphosus scolopax, gobids, Gadiculus argenteus, and most of Crustacea. The diet does not appear to be influenced by sex (>0.05). A trophic level (TROPH) of 4.1 was calculated, indicating that the species is a top predator (quaternary consumers). The TROPH values ranged between 2.58 and 4.38 from juveniles to adults, increasing asymptotically with the size of specimens. In contrast to what has previously been found in other Mediterranean regions, where ichthyophagous hake feed mostly on pelagic Osteichthyes, such as Engraulis encrasicolus, Sardina pilchardus, and Micromesistius poutassou, the study points up the vital role played by Atlantic horse mackerel Trachurus trachurus for hake diet in the Moroccan Mediterranean Sea. Information on the feeding ecology of fish species as provided in this study is essential to improve ecosystem conservation in accordance with multispecies approach to fishery management, leading to a better understanding of the role of hake in the Moroccan Mediterranean Sea demersal communities.

The function of the feeding groove of 'typical excavate' flagellates.

Phagotrophic flagellates are the main consumers of bacteria and picophytoplankton. Despite their ecological significance in the 'microbial loop', many of their predation mechanisms remain unclear. 'Typical excavates' bear a ventral groove, where prey is captured for ingestion. The consequences of feeding through a 'semi-rigid' furrow on the prey size range have not been explored. An unidentified moving element called 'the wave' that sweeps along the bottom of the groove toward the site of phagocytosis has been observed in a few species; its function is unclear. We investigated the presence, behavior, and function of the wave in four species from the three excavate clades (Discoba, Metamonada, and Malawimonadida) and found it present in all studied cases, suggesting the potential homology of this feature across all three groups. The wave displayed a species-specific behavior and was crucial for phagocytosis. The morphology of the feeding groove had an upper-prey size limit for successful prey captures, but smaller particles were not constrained. Additionally, the ingestion efficiencies were species dependent. By jointly studying these feeding traits, we speculate on adaptations to differences in food availability to better understand their ecological functions.