Thoracic Legs Research Articles

Microbiology, induction, and management practices to mitigate lameness caused by bacterial chondronecrosis with osteomyelitis in broiler chickens

Bacterial chondronecrosis with osteomyelitis (BCO) lameness is the most prevalent skeletal disorder in poultry, implicated by the inherent risk of the high growth rate of modern broilers. The non-synchronization of massive body mass accretion vs maturation of the structural bone induces vulnerability to bone microfracture and immunosuppression, leading to bacterial necrosis in the skeletal and thoracic vertebral bones, leg paralysis, and eventual death. BCO lameness also imposes animal welfare issues and confers food safety risks. A study in 20 broiler farms in Australia recorded 28% BCO lesions of the necropsied birds, while a study in commercial flocks in Europe reported 19% moderate-to-severe lameness symptoms. The high incidence of lameness in commercial broiler farms reduces production value and leads to a huge economic loss in the poultry industry. Managing BCO lameness in broiler poultry is more challenging than that of other species because the peak of lameness incidence emerges at the marketing age of broilers. Moreover, curative treatment of the affected broilers is arduous due to their larger populations but shorter production cycles. Thus, condemnation of clinically lame birds has been a common practice in broiler farms to prevent the transmission of highly contagious BCO throughout the broiler populations. This practice decreases the production value and increases the economic forfeits. Therefore, presenting intervention measures for managing and controlling BCO in broiler poultry is necessary. Knowledge of etiological agents, pathogenesis, detection, and experimental lameness models to evaluate the efficacy of the intervention measures is highly important in presenting approaches to mitigate BCO lameness. Thus, this review focuses on microbiology studies of BCO, models of creating experimental lameness, and intervention measures mitigating BCO lameness in broiler chickens.

Larval morphology of a Palearctic Rutelini, Parastasia ferrieri (Coleoptera, Scarabaeidae), with discussions on their feeding habits

Rutelini is one of the largest tribes of Rutelinae, widely distributed but primarily in the New World. Recently, both larvae and adults of Parastasia ferrieri had been discovered in Liaoning Province of northeastern China from the Palearctic realm. The third-instar larvae of P. ferrieri were described using light and scanning electron microscopy in order to discover more morphological characters for larval taxonomy. The larvae of P. ferrieri exhibit remarkable features, including four protuberances on labrum, no helus on epipharynx, two scissorial teeth on each mandible, five stridulatory teeth plus a blunt protuberance on each maxilla, and the obtuse claws on the thoracic legs. The correlation between morphological features and feeding habits is briefly discussed.

Cross-instar larval identification leads divergent decision on pest management: An example from white grubs on peanuts

Accurate larval identification is a prerequisite for integrated pest management, but remains a long-term difficulty in insect taxonomy. Previous descriptions are mainly focused on the most disruptive final instar larvae. However, earlier instars especially cross-instar larval morphological comparisons were rarely delivered hitherto. Polyphylla laticollis and Maladera orientalis are pests that damage peanut crops at various developmental stages. The first instar larvae of P. laticollis and the mature larvae of M. orientalis attack peanuts simultaneously and cause different types of damage. In this study, we compared the life histories and larval morphologies through field investigations and scanning electron microscopy (SEM) observations. These cross-instar white grubs are similar in sizes, but exhibit morphological differences on their mouthparts, thoracic legs, anal slits, and rasters. This study presents a novel approach to larval identification, with a goal of generating new insights into integrated pest control practices on white grubs.

Kinematic characteristics of calanoid copepod appendage motion

Abstract Propulsion by copepods requires high-speed video and intensive analyses. Routine smooth swimming is compared with small relocation jumps and escape reactions, relying on kinematics analyses of appendage movement. In this study, we used high-speed video at 1200 frames per second to determine the kinematic parameters of three types of swimming in Eurytemora affinis females: routine steady swimming, small relocation jumps and escape reactions. The average speed varied in the range 0.30–0.82 cm s−1 during steady routine swimming. This value increased to 4.48 ± 1.01 cm s−1 during small relocation jumps, and reached 21.94 ± 2.68 cm s−1 during escape reactions. The small angular amplitude (40–50°) and the very high beat frequency (63–80 Hz) of the cephalic appendages during routine swimming indicate that E. affinis is a feeding-current feeder. The comparison of the angular displacements of the antennules, thoracic legs and abdomen with respect to the movement speed demonstrates that, both in the case of small relocation jumps and during escape reactions, the main propulsive role is played by the thoracic swimming legs and abdomen.

CRISPR/Cas9-Mediated Mutagenesis of Antennapedia in Spodoptera frugiperda.

The homeotic gene Antennapedia (Antp) has been identified as playing a pivotal role in the morphogenesis of the thorax and wings across various insect species. Leveraging insights from previous studies, the functional characterization of Antp in S. frugiperda was undertaken using RT-qPCR and the CRISPR/Cas9 genome-editing system. Phylogenetic analyses indicate that Antp shares a high degree of sequence homology among Lepidoptera species. The expression profile of SfAntp was detected by RT-qPCR. The results showed that SfAntp was expressed in the whole growth cycle of S. frugiperda, the expression level was the highest in the egg stage, and the expression level was higher from 12 h to 48 h. Tissue-specific expression profiling demonstrated that SfAntp was most abundantly expressed in the thoracic segments and legs. To functionally disrupt SfAntp, two sgRNA sites were designed at the first exon of SfAntp and the gene was knocked out by CRISPR/Cas9 via microinjection. The results showed that the deletion of SfAntp produced a mutant phenotype of thoracic fusion, thoracic leg defect, leg-like protrusions between the head and thoracic segments and pupation deformity. In addition, deletion of SfAntp resulted in high embryo mortality. Through DNA sequencing, it was found that the target site of the SfAntp mutant had different degrees of frameshift mutations, indicating that the mutant phenotype was indeed caused by the knockout of SfAntp.

The Effects of Nine Compounds on Aldehyde-Oxidase-Related Genes in Bactrocera dorsalis (Hendel).

Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) (B. dorsalis) is an important agricultural, major invasive, and quarantine pest that can cause significant damage to the economic value of the fruit and vegetable industry. Male bait is one of the most effective methods of surveying, monitoring, and controlling B. dorsalis. In our study, we constructed cDNA libraries using total RNA extracted independently from the antennae, mouthparts, and thoracic legs of male and female adults and the ovipositors of female adults and screened out four aldehyde-oxidase-related genes (AOX-related), C58800, C66700, C67485, and C67698. Molecular docking predictions showed that eight compounds, including 3,4-dimethoxycinnamyl alcohol, 3,4-dimethoxy-cinnamaldehyde, deet, ethyl N-acetyl-N-butyl-β-alaninate, n-butyl butyrate, n-butyl butyrate, ethyl butyrate, methyl eugenol, and ethyl acetate, could combine with proteins encoded by the four B. dorsalis AOX-related genes. Furthermore, QPCR was performed to confirm that four compounds, including 3,4-dimethoxy cinnamic aldehyde, butyl levulinic acid ethyl ester (mosquito repellent), butyl butyrate, and methyl eugenol, induced significant changes in the AOX-related genes of B. dorsalis. These results provide useful information and guidance for the batch screening of potentially useful compounds and the search for effective attractants of B. dorsalis.

Lepidopteran prolegs are novel traits, not leg homologs.

Lepidopteran larvae have both thoracic legs and abdominal prolegs, yet it is unclear whether these are serial homologs. A RNA-seq analysis with various appendages of Bicyclus anynana butterfly larvae indicated that the proleg transcriptome resembles the head-horn transcriptome, a novel trait in the lepidoptera, but not a thoracic leg. Under a partial segment abdominal-A (abd-A) knockout, both thoracic leg homologs (pleuropodia) and prolegs developed in the same segment, arguing that both traits are not serial homologs. Further, three of the four coxal marker genes, Sp5, Sp6-9, and araucan, were absent from prolegs, but two endite marker genes, gooseberry and Distal-less, were expressed in prolegs, suggesting that prolegs may be using a modular endite gene-regulatory network (GRN) for their development. We propose that larval prolegs are novel traits derived from the activation of a pre-existing modular endite GRN in the abdomen using abd-A, the same Hox gene that still represses legs in more lateral positions.

Species-specific larval acoustic behaviour of three stag beetles (Coleoptera: Lucanidae), with emphasis on their stridulatory organs and acoustic signals

Acoustic behaviour plays a significant role in insect communications, but is rarely reported in their immature stages. Larvae of Lucanidae bear paired stridulatory organs on their thoracic legs, which could produce sounds as communicational signals. However, the species-specific differences on stridulatory organs and acoustic signals are far from fully investigated. In this study, the larval acoustic behaviours of three lucanid species, Lucanus dybowski, Prosopocoilus confucius and P. girafa were recorded and compared for the first time. The sound producing mechanism was described in detail based on video recordings, morphological observations, and acoustic analyses. The larvae of all three species are able to produce sounds by scraping the plectrum on the metatrochanter against the pars stridens on the mesocoxa during disturbance. The sounds exhibit species-specific differences in terms of acoustic parameters: the larvae of L. dybowski produce short-duration (140–200 ms), single-pulse and low-frequency (∼210 Hz) sounds; P. confucius produce long-duration (500–800 ms), triple-pulse and low-frequency (∼280 Hz) sounds; P. girafa produce long-duration (500–560 ms), double-pulse and low-frequency (∼260 Hz) sounds. The amounts and arrangements of the teeth on stridulatory organs also exhibit differences on specific level. The acoustic signals and stridulatory organs were compared using principal component analysis.

Two new species of Cerviniella Smirnov, 1946 (Copepoda, Harpacticoida, Aegisthidae) from the Yellow Sea, Korea.

Two new species, Cerviniellabisegmentasp. nov. and C.permixtasp. nov., are described in detail with illustrations based on females from the Korean Yellow Sea. These species lacking the fourth leg endopod belong to the mirabilipes group, one of two species groups within the genus Cerviniella Smirnov, 1946. Both species can be distinguished from each other by the surface ornamentation of the cephalothorax, shape of the rostrum tip, antennule segments, armature formula of thoracic legs 1-4, and length ratio of the caudal rami. Cerviniellabisegmentasp. nov. is characterized by a short caudal ramus and a two-segmented antennary exopod, which are unique within the genus. Cerviniellapermixtasp. nov. differs from other congeners of the mirabilipes group by the seven-segmented antennule, the armature formulae of the exopod of the antenna and thoracic legs 1-4, and the modified apical inner element of the second endopodal segment of the second leg. The present study is the first to identify the genus Cerviniella in Korean waters, resulting in extension of its distribution area to East Asia.

Scanning Electron Microscopy and First Molecular Data of Two Species of Lamproglena (Copepoda: Lernaeidae) from Labeo victorianus (Cyprinidae) and Clarias gariepinus (Clariidae) in Kenya.

A parasitological study carried out in May 2022 and March 2023 in the Nyando River of Lake Victoria Basin, Kenya, disclosed two parasitic lernaeid copepods: Lamproglena cleopatra Humes, 1957, from the gills of a cyprinid, the Ningu Labeo victorianus Boulenger, 1901, endemic to the Lake Victoria drainage system, and Lamproglena clariae Fryer, 1957, from a clariid, the North African catfish Clarias gariepinus (Burchell, 1822). The copepods were studied and supplementary taxonomic information was presented using scanning electron micrographs and genetic data. Scanning electron microscopy (SEM) provided information on the morphology of L. cleopatra's antennae, oral region, thoracic legs (2-5), and furcal rami not previously reported. Analyses of the partial fragments of 18S and 28S rDNA and cytochrome c oxidase subunit 1 (cox1) of the two parasites showed them to be distinct from all other Lamproglena taxa retrieved from GenBank. This study presents new taxonomic information on morphology using SEM and provides the first ribosomal (18S and 28S rDNA) and mitochondrial (mtDNA) data for these two parasite species. The cox1 data provided are the first for all 38 nominal species of Lamproglena. Notably, the study also provides a new host record for L. cleopatra and extends the geographical information of this species to Kenya.

Positioning of pivot points in quadrupedal locomotion: limbs global dynamics in four different dog breeds.

Dogs (Canis familiaris) prefer the walk at lower speeds and the more economical trot at speeds ranging from 0.5 Fr up to 3 Fr. Important works have helped to understand these gaits at the levels of the center of mass, joint mechanics, and muscular control. However, less is known about the global dynamics for limbs and if these are gait or breed-specific. For walk and trot, we analyzed dogs' global dynamics, based on motion capture and single leg kinetic data, recorded from treadmill locomotion of French Bulldog (N = 4), Whippet (N = 5), Malinois (N = 4), and Beagle (N = 5). Dogs' pelvic and thoracic axial leg functions combined compliance with leg lengthening. Thoracic limbs were stiffer than the pelvic limbs and absorbed energy in the scapulothoracic joint. Dogs' ground reaction forces (GRF) formed two virtual pivot points (VPP) during walk and trot each. One emerged for the thoracic (fore) limbs (VPPTL) and is roughly located above and caudally to the scapulothoracic joint. The second is located roughly above and cranially to the hip joint (VPPPL). The positions of VPPs and the patterns of the limbs' axial and tangential projections of the GRF were gaits but not always breeds-related. When they existed, breed-related changes were mainly exposed by the French Bulldog. During trot, positions of the VPPs tended to be closer to the hip joint or the scapulothoracic joint, and variability between and within breeds lessened compared to walk. In some dogs, VPPPL was located below the pelvis during trot. Further analyses revealed that leg length and not breed may better explain differences in the vertical position of VPPTL or the horizontal position of VPPPL. The vertical position of VPPPL was only influenced by gait, while the horizontal position of VPPTL was not breed or gait-related. Accordingly, torque profiles in the scapulothoracic joint were likely between breeds while hip torque profiles were size-related. In dogs, gait and leg length are likely the main VPPs positions' predictors. Thus, variations of VPP positions may follow a reduction of limb work. Stability issues need to be addressed in further studies.

Silk‐assisted hatching of the Japanese bagworm moth Eumeta variegata (Lepidoptera: Psychidae)

AbstractBagworms constantly carry a portable bag with their prolegs inside, even when walking. Therefore, bagworms have a unique walking style. Bagworms construct footholds with silk and walk using only their thoracic legs. Bagworms build their bag immediately after hatching and carry them for the rest of their lives. Therefore, the only period when they move without a bag is immediately after hatching, when they move away from the hatched egg. We assessed their movement behavior in the period immediately after hatching when all legs were available, including prolegs. Our observations revealed that hatching Eumeta variegata (Japan's largest bagworm species) spun foothold silk threads even as they left the egg. From the moment the head broke out of the egg, larvae began spinning foothold silk threads. To do this, larvae twisted their anterior regions approximately 90° immediately before hatching. This finding indicates that larvae prepare to spin foothold silk threads during embryonic development.

Toxicity and synergistic activity of compounds from essential oils and their effect on detoxification enzymes against Planococcus lilacinus.

Mealybug, Planococcus lilacinus Cockerell, is a primary surface-feeding insect pest of fruit and flowering plants and also transmits plant viruses, resulting in economic crop loss. Inappropriate and recurrent use of pesticides for mealybug control results in resistance building and deleterious effects on humans and the environment. Essential oils are the most excellent choice for insecticides. Insecticidal activities of pure compounds of essential oils against P. lilacinus are not reported. The present study aims to study the insecticidal activities of some pure active compounds and their binary mixture's action by topical application against P. lilacinus. Results showed that the pure compounds of L-limonene, β-myrcene, and ocimene revealed toxicity (each at LD50 = 0.37 µg/insect) after 96h. The binary mixtures of geraniol + L-menthol and L-limonene + geraniol exhibited synergistic effects (each at LD50 = 0.03 µg/insect) after 96h. The monoterpenes of ocimene and β-myrcene at the higher concentration of 5,000 ppm substantially inhibited the detoxification enzyme activities of AChE (0.93 and 0.78 mU/mg, respectively) and GST (2.19 and 7.29 nmol/min/ml, respectively) in P. lilacinus after 48h. SEM analysis reported the significant anomalies on the morphology of abdominal cuticle, setae, and thoracic leg after 96-h treatment with ocimene at 1,250 ppm against P. lilacinus. Based on the results, the tested pure compounds and their combinations can be suggested for the control of mealybugs.

New ostracod species (Cypridopsis schwartzi n. sp.) from Texas, with discussion on the taxonomic status of Cypridopsis species in the USA

A total of 39 taxa (19 living species, 20 subfossils) were collected from 59 different shallow aquatic bodies in Texas during April to June 2017. Cypridopsis schwartzi n. sp. is proposed as a new species collected from a cattle pond at Freeman Ranch near San Marcos, Texas. The species has several characteristics separating it from other species, including carapace shape, presence of a curved z3-seta on the second antenna, number of setae on the vibratory plate of the first thoracic leg, shape of hemipenis, numbers of whorls on the Zenker organ, and several other differences. With the new species, there are now 12 species in the genus Cypridopsis recorded for Texas, and Cypridopsis schwartzi n. sp. is the fifth species of the genus in Texas showing sexual reproduction. The new species was compared with other species of the genus in Texas and the taxonomic relationships are discussed.

A new alternative splice variant of ecdysteroid receptor ( EcR ) transcript differentially expressed during embryogenesis in the oriental river prawn Macrobrachium nipponense

Ecdysteroids are well known as a class of steroid hormones, which not only mediate moulting in insects and crustaceans but also are involved in the reproduction and embryogenesis as well. To characterize the role of ecdysteroid receptor (EcR) in embryogenesis, a novel alternative splicing of EcR (MnEcR) was identified from the oriental river prawn Macrobrachium nipponense, and its spatio-temporal expression profile was examined during embryogenesis. The MnEcR cDNA is 2246 bp in length and encodes a protein with 487 amino acids. Quantitative real-time PCR analysis revealed that the relative amount of MnEcR transcripts was low at cleavage stage, gradually increased from blastula stage, and reached at a peak at the metanauplius when the Y-organ appeared and, thereafter, dramatically decreased at the protozoea and back to a low level at the zoea. Such a dynamic expression profile of MnEcR mRNA is paralleled by fluctuation of ecdysteroids during morphogenesis in the prawn M. rosenbergii and Palaemon serratus. Hybridization in situ demonstrated MnEcR transcripts were localized to the epidermis of appendage rudiments in metanauplius and the cuticle membrane of the thoracic legs and telson in zoeas, suggesting a role for MnEcR in the development of appendages. These results indicated that MnEcR associated with ecdysteroids might be essential for morphogenesis during embryogenesis in the prawn.

Swimming and respiration in cyclopoid copepods Thermocyclops oithonoides and Oithona davisaeand calanoid copepod Paracalanus parvus.

Cyclopoid and calanoid copepods differ in how they move. Cyclopoid copepods use the thoracic legs for cruise and escape swimming while most calanoid copepods use the cephalic appendages for cruise swimming and the thoracic legs for escape reactions. Apart from this gross difference, little is known on the comparative aspects of the locomotor function of copepod appendages. This study investigated the main kinematic patterns of cruise and escape swimming of two small cyclopoid copepods, Thermocyclops oithonoides and Oithona davisae, and a small calanoid copepod, Paracalanus parvus, by video filming at a frame rate of up to 1200 frames/s. During escape swimming, O. davisae and the twice as large P. parvus showed similar movement, jumping at a frequency of 150 Hz and moving at 12 cm s-1 ; however, at a lower jump frequency (∼100 Hz), the cyclopoid T. oithonoides showed an almost two times faster escape swimming than that of P. parvus which has the same body size. This higher speed can be linked to the greater role of the longer abdomen for the flopping strokes in T. oithonoides. In accordance with the Arrhenius law, the kinematic parameters of cruise and escape swimming of T. oithonoides showed temperature dependence in the range of 6.5-27°С. At a temperature of about 20°C, the respiration rate of O. davisae and P. parvus was 1.6 times higher (i.e., ∼1.5 µg O2 mg-1 h-1 ) than in T. oithonoides during normal swimming; however, in the swarming state, the respiration rate of T. oithonoides increased 3.4 times to 3.0 µg O2 mg-1 h-1 , which was nine times higher than the respiratory rate of anesthetized individuals of this species. Based on the speed and duration of locomotor acts, the cyclopoid T. oithonoides consumed about the same amount of respiratory energy as the calanoid P. parvus, but the mechanical energy required for movement in jumps mode was 1.5 times higher.

Transcription factor paralogs orchestrate alternative gene regulatory networks by context-dependent cooperation with multiple cofactors

In eukaryotes, members of transcription factor families often exhibit similar DNA binding properties in vitro, yet orchestrate paralog-specific gene regulatory networks in vivo. The serially homologous first (T1) and third (T3) thoracic legs of Drosophila, which are specified by the Hox proteins Scr and Ubx, respectively, offer a unique opportunity to address this paradox in vivo. Genome-wide analyses using epitope-tagged alleles of both Hox loci in the T1 and T3 leg imaginal discs, the precursors to the adult legs and ventral body regions, show that ~8% of Hox binding is paralog-specific. Binding specificity is mediated by interactions with distinct cofactors in different domains: the Hox cofactor Exd acts in the proximal domain and is necessary for Scr to bind many of its paralog-specific targets, while in the distal leg domain, the homeodomain protein Distal-less (Dll) enhances Scr binding to a different subset of loci. These findings reveal how Hox paralogs, and perhaps paralogs of other transcription factor families, orchestrate alternative downstream gene regulatory networks with the help of multiple, context-specific cofactors.

Biological and morphological studies on the parasitoids (Hymenoptera, Ichneumonidae) of Aprosthema tardum (Klug) (Hymenoptera, Argidae, Sterictiphorinae) in Var, southern France

Field surveys at four neighbouring but discrete sites in southern France revealed the presence of five ichneumonid parasitoids of the Lathyrus-feeding sterictiphorine argid sawfly Aprosthema tardum. Four of these parasitoids, Lathrolestes erythrocephalus, Ischyrocnemis goesi (both Ctenopelmatinae), Terozoa quadridens and Thibetoides aprosthemae (both Tryphoninae), could be identified and, by also incorporating laboratory studies, the developmental biology of each was elucidated and illustrated. A little supplementary information from a site in Italy is also presented. The fifth species was detected only once and failed to develop in its cocoon; it remains unidentified but the cephalic sclerites of its final instar larva are illustrated. The identified parasitoids are all more or less rare and little-known species and prior to this study only L. erythrocephalus had a known host; the others were biologically unknown even at the generic level and not recorded from France. The egg of L. erythrocephalus bears prominent hooked structures at its capital end, not reported in other studied Lathrolestes species. From its biology as an endoparasitoid of a sawfly and from larval characters, Ischyrocnemis is confidently assigned to Ctenopelmatinae. Both ctenopelmatines could successfully parasitise the host during any of its 2nd to 5th instars, but the tryphonines were less flexible. Terozoa monitors hosts until the moult to the final instar before ovipositing on them, usually affixing the egg to the head and often an eye (stemma), while Thibetoides parasitises much younger hosts, placing its strongly anchored egg behind a thoracic leg where it remains through successive host moults. Some characters used in the past to determine Terozoa species are discussed, and a new provisional key to the known species of Terozoa is presented. The very different developmental biology of Terozoa and Thibetoides may challenge views that they are closely related genera. Terozoa bituberculata (Constantineanu, 1973), stat. rev. is raised from synonymy with T. quadridens Perkins, 1962. Reinterpretations of several cephalic structures of final instar larvae as well as larval spiracles are discussed, and a new interpretation and terminology for describing the latter is introduced.

Thorax-Segment- and Leg-Segment-Specific Motor Control for Adaptive Behavior.

We have just started to understand the mechanisms underlying flexibility of motor programs among segmental neural networks that control each individual leg during walking in vertebrates and invertebrates. Here, we investigated the mechanisms underlying curve walking in the stick insect Carausius morosus during optomotor-induced turning. We wanted to know, whether the previously reported body-side specific changes in a two-front leg turning animal are also observed in the other thoracic leg segments. The motor activity of the three major leg joints showed three types of responses: 1) a context-dependent increase or decrease in motor neuron (MN) activity of the antagonistic MN pools of the thorax-coxa (ThC)-joint during inside and outside turns; 2) an activation of 1 MN pool with simultaneous cessation of the other, independent of the turning direction in the coxa-trochanteral (CTr)-joint; 3) a modification in the activity of both FTi-joint MN pools which depended on the turning direction in one, but not in the other thorax segment. By pharmacological activation of the meso- or metathoracic central pattern generating networks (CPG), we show that turning-related modifications in motor output involve changes to local CPG activity. The rhythmic activity in the MN pools of the ThC and CTr-joints was modified similarly to what was observed under control conditions in saline. Our results indicate that changes in meso- and metathoracic motor activity during curve walking are leg-joint- and thorax-segment-specific, can depend on the turning direction, and are mediated through changes in local CPG activity.

Dining on crude oil at the bottom of the food chain

Filter feeders come in all sizes, from massive blue whales lunging through the water with their colossal mouths wide open to tiny barnacles wafting feathery feeding appendages through the top of their shells to entrap minute morsels. Yet, all of these creatures are at risk of ingesting other unwanted contamination, including dispersed droplets of crude oil. And inadvertent ingestion of oil by the smallest feeders, such as Daphnia, places animals further up the food chain at risk from the pollution. But no one knew how small filter feeders pick up miniscule droplets of oil carried in water, so Francis Letendre and Christopher Cameron from the University of Montreal, Canada, filmed two members of the acorn barnacle family (the relatively large Balanus glandula and smaller B. crenatus) and Daphnia magna water fleas to find out how they harvest crude oil droplets from water flowing past.Securing the barnacles in a tank with water flowing at speeds from 1.4 to 24 cm s−1, Letendre filmed the animals as they extended their feathery feeding tentacles, sometimes allowing the tentacles to waft gently in the flow while on other occasions the structures seemed to reach out and grasp the water before being rapidly withdrawn back into the shell. However, when the scientists calculated the stickiness of the water flowing past the feathery structures wafting in the slower streams (less than 10 cm s−1), they realised that the water was essentially coating each fine hair so that the gaps between the hairs were effectively clogged, transforming each filagree feeding structure into a solid paddle, intercepting droplets of oil in the static layer of water coating the structure. However, as the water speeded up, it became more slippery, flowing through the structures lodging droplets of oil against the hairs, ready for the barnacle to scrape them free with its mouth after retracting the tentacles back within its shell.In contrast, the tiny Daphnia wafted water carrying droplets of crude oil into their mouths by pulsating all four pairs of thoracic legs in a rippling Mexican wave. However, the hairs coating the lower two pairs of rippling legs also became clogged with oil. And when the team left water fleas swimming freely for 48 h in fine mists of crude oil droplets – less than 10 μm in diameter – all the Daphnia ingested some of the toxic oil ready to pass on to any creature that chose to dine on them. In addition, the duo calculated the stickiness of water around the fine hairs coating the antennae and they too became coated in the relatively thick water, transforming the filamentous structures into paddles ideal for propelling the animals through the water while leaving the antennae oil free.Having begun to discover how animals at the bottom of the food chain might ingest droplets of crude oil, the team would like to learn more about how these filter feeders cope when bathed in the larger oil droplets generated by oil tanker spills and rig disasters. And they are curious to learn how different shapes of shell affect how barnacles entrap the oil globules that drift their way.