S. French, S. Hudson, A. Webb, C. R. Knapp, Emily E. Virgin, Geoffrey D. Smith, Erin L Lewis, J. Iverson, D. DeNardo
There is great interspecific variation in the nutritional composition of natural diets, and the varied nutritional content is physiologically tolerated because of evolutionarily based balances between diet composition and processing ability. However, as a result of landscape change and human exposure, unnatural diets are becoming widespread among wildlife without the necessary time for evolutionary matching between the diet and its processing. We tested how a controlled, unnatural high glucose diet affects glucose tolerance using captive green iguanas, and we performed similar glucose tolerance tests on wild Northern Bahamian rock iguanas that are either frequently fed grapes by tourists or experience no such supplementation. We evaluated both short and longer-term blood glucose responses and corticosterone (CORT) concentrations as changes have been associated with altered diets. Experimental glucose supplementation in the laboratory and tourist feeding in the wild both significantly affected glucose metabolism. When iguanas received a glucose-rich diet, we found greater acute increases in blood glucose following a glucose challenge. Relative to unfed iguanas, tourist-fed iguanas had significantly lower baseline CORT, higher baseline blood glucose, and slower returns to baseline glucose levels following a glucose challenge. Therefore, unnatural consumption of high amounts of glucose alters glucose metabolism in laboratory iguanas with short-term glucose treatment and free-living iguanas exposed to long-term feeding by tourists. Based on these results and the increasing prevalence of anthropogenically altered wildlife diets, the consequences of dietary changes on glucose metabolism should be further investigated across species, as such changes in glucose metabolism have health consequences in humans (e.g. diabetes).
{"title":"Glucose tolerance of iguanas is affected by high-sugar diets in the lab and supplemental feeding by ecotourists in the wild.","authors":"S. French, S. Hudson, A. Webb, C. R. Knapp, Emily E. Virgin, Geoffrey D. Smith, Erin L Lewis, J. Iverson, D. DeNardo","doi":"10.1242/jeb.243932","DOIUrl":"https://doi.org/10.1242/jeb.243932","url":null,"abstract":"There is great interspecific variation in the nutritional composition of natural diets, and the varied nutritional content is physiologically tolerated because of evolutionarily based balances between diet composition and processing ability. However, as a result of landscape change and human exposure, unnatural diets are becoming widespread among wildlife without the necessary time for evolutionary matching between the diet and its processing. We tested how a controlled, unnatural high glucose diet affects glucose tolerance using captive green iguanas, and we performed similar glucose tolerance tests on wild Northern Bahamian rock iguanas that are either frequently fed grapes by tourists or experience no such supplementation. We evaluated both short and longer-term blood glucose responses and corticosterone (CORT) concentrations as changes have been associated with altered diets. Experimental glucose supplementation in the laboratory and tourist feeding in the wild both significantly affected glucose metabolism. When iguanas received a glucose-rich diet, we found greater acute increases in blood glucose following a glucose challenge. Relative to unfed iguanas, tourist-fed iguanas had significantly lower baseline CORT, higher baseline blood glucose, and slower returns to baseline glucose levels following a glucose challenge. Therefore, unnatural consumption of high amounts of glucose alters glucose metabolism in laboratory iguanas with short-term glucose treatment and free-living iguanas exposed to long-term feeding by tourists. Based on these results and the increasing prevalence of anthropogenically altered wildlife diets, the consequences of dietary changes on glucose metabolism should be further investigated across species, as such changes in glucose metabolism have health consequences in humans (e.g. diabetes).","PeriodicalId":22458,"journal":{"name":"THE EGYPTIAN JOURNAL OF EXPERIMENTAL BIOLOGY","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85041481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fleur Visser, M. Oudejans, Onno A. Keller, Peter T. Madsen, Mark Johnson
ABSTRACT Closely related species are expected to diverge in foraging strategy, reflecting the evolutionary drive to optimize foraging performance. The most speciose cetacean genus, Mesoplodon, comprises beaked whales with little diversity in external morphology or diet, and overlapping distributions. Moreover, the few studied species of beaked whales (Ziphiidae) show very similar foraging styles with slow, energy-conserving movement during long, deep foraging dives. This raises the question of what factors drive their speciation. Using data from animal-attached tags and aerial imagery, we tested the hypothesis that two similar-sized mesoplodonts, Sowerby's (Mesoplodon bidens) and Blainville's (Mesoplodon densirostris) beaked whales, exploit a similar low-energy niche. We show that, compared with the low-energy strategist Blainville's beaked whale, Sowerby's beaked whale lives in the fast lane. While targeting a similar mesopelagic/bathypelagic foraging zone, they consistently swim and hunt faster, perform shorter deep dives, and echolocate at a faster rate with higher frequency clicks. Further, extensive near-surface travel between deep dives challenges the interpretation of beaked whale shallow inter-foraging dives as a management strategy for decompression sickness. The distinctively higher frequency echolocation clicks do not hold apparent foraging benefits. Instead, we argue that a high-speed foraging style influences dive duration and echolocation behaviour, enabling access to a distinct prey population. Our results demonstrate that beaked whales exploit a broader diversity of deep-sea foraging and energetic niches than hitherto suspected. The marked deviation of Sowerby's beaked whales from the typical ziphiid foraging strategy has potential implications for their response to anthropogenic sounds, which appears to be strongly behaviourally driven in other ziphiids.
{"title":"Sowerby's beaked whale biosonar and movement strategy indicate deep-sea foraging niche differentiation in mesoplodont whales","authors":"Fleur Visser, M. Oudejans, Onno A. Keller, Peter T. Madsen, Mark Johnson","doi":"10.1242/jeb.243728","DOIUrl":"https://doi.org/10.1242/jeb.243728","url":null,"abstract":"ABSTRACT Closely related species are expected to diverge in foraging strategy, reflecting the evolutionary drive to optimize foraging performance. The most speciose cetacean genus, Mesoplodon, comprises beaked whales with little diversity in external morphology or diet, and overlapping distributions. Moreover, the few studied species of beaked whales (Ziphiidae) show very similar foraging styles with slow, energy-conserving movement during long, deep foraging dives. This raises the question of what factors drive their speciation. Using data from animal-attached tags and aerial imagery, we tested the hypothesis that two similar-sized mesoplodonts, Sowerby's (Mesoplodon bidens) and Blainville's (Mesoplodon densirostris) beaked whales, exploit a similar low-energy niche. We show that, compared with the low-energy strategist Blainville's beaked whale, Sowerby's beaked whale lives in the fast lane. While targeting a similar mesopelagic/bathypelagic foraging zone, they consistently swim and hunt faster, perform shorter deep dives, and echolocate at a faster rate with higher frequency clicks. Further, extensive near-surface travel between deep dives challenges the interpretation of beaked whale shallow inter-foraging dives as a management strategy for decompression sickness. The distinctively higher frequency echolocation clicks do not hold apparent foraging benefits. Instead, we argue that a high-speed foraging style influences dive duration and echolocation behaviour, enabling access to a distinct prey population. Our results demonstrate that beaked whales exploit a broader diversity of deep-sea foraging and energetic niches than hitherto suspected. The marked deviation of Sowerby's beaked whales from the typical ziphiid foraging strategy has potential implications for their response to anthropogenic sounds, which appears to be strongly behaviourally driven in other ziphiids.","PeriodicalId":22458,"journal":{"name":"THE EGYPTIAN JOURNAL OF EXPERIMENTAL BIOLOGY","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77917456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Howald, M. Moyano, A. Crespel, Luis L Kuchenmüller, Louise Cominassi, G. Claireaux, M. Peck, F. Mark
European sea bass (Dicentrarchus labrax) is a large, economically important fish species with a long generation time whose long-term resilience to ocean acidification (OA) and warming (OW) is not clear. We incubated sea bass from Brittany (France) for two generations (>5 years in total) under ambient and predicted OA conditions (PCO2: 650 and 1700 µatm) crossed with ambient and predicted ocean OW conditions in F1 (temperature: 15-18°C and 20-23°C) to investigate the effects of climate change on larval and juvenile growth and metabolic rate. We found that in F1, OA as single stressor at ambient temperature did not affect larval or juvenile growth and OW increased developmental time and growth rates, but OAW decreased larval size at metamorphosis. Larval routine and juvenile standard metabolic rates were significantly lower in cold compared to warm conditioned fish and also lower in F0 compared to F1 fish. We did not find any effect of OA as a single stressor on metabolic rates. Juvenile PO2crit was not affected by OA or OAW in both generations. We discuss the potential underlying mechanisms resulting in the resilience of F0 and F1 larvae and juveniles to OA and in the beneficial effects of OW on F1 larval growth and metabolic rate, but on the other hand in the vulnerability of F1, but not F0 larvae to OAW. With regard to the ecological perspective, we conclude that recruitment of larvae and early juveniles to nursery areas might decrease under OAW conditions but individuals reaching juvenile phase might benefit from increased performance at higher temperatures.
{"title":"Effects of Ocean Acidification over successive generations decrease larval resilience to Ocean Acidification & Warming but juvenile European sea bass could benefit from higher temperatures in the NE Atlantic.","authors":"S. Howald, M. Moyano, A. Crespel, Luis L Kuchenmüller, Louise Cominassi, G. Claireaux, M. Peck, F. Mark","doi":"10.1242/jeb.243802","DOIUrl":"https://doi.org/10.1242/jeb.243802","url":null,"abstract":"European sea bass (Dicentrarchus labrax) is a large, economically important fish species with a long generation time whose long-term resilience to ocean acidification (OA) and warming (OW) is not clear. We incubated sea bass from Brittany (France) for two generations (>5 years in total) under ambient and predicted OA conditions (PCO2: 650 and 1700 µatm) crossed with ambient and predicted ocean OW conditions in F1 (temperature: 15-18°C and 20-23°C) to investigate the effects of climate change on larval and juvenile growth and metabolic rate. We found that in F1, OA as single stressor at ambient temperature did not affect larval or juvenile growth and OW increased developmental time and growth rates, but OAW decreased larval size at metamorphosis. Larval routine and juvenile standard metabolic rates were significantly lower in cold compared to warm conditioned fish and also lower in F0 compared to F1 fish. We did not find any effect of OA as a single stressor on metabolic rates. Juvenile PO2crit was not affected by OA or OAW in both generations. We discuss the potential underlying mechanisms resulting in the resilience of F0 and F1 larvae and juveniles to OA and in the beneficial effects of OW on F1 larval growth and metabolic rate, but on the other hand in the vulnerability of F1, but not F0 larvae to OAW. With regard to the ecological perspective, we conclude that recruitment of larvae and early juveniles to nursery areas might decrease under OAW conditions but individuals reaching juvenile phase might benefit from increased performance at higher temperatures.","PeriodicalId":22458,"journal":{"name":"THE EGYPTIAN JOURNAL OF EXPERIMENTAL BIOLOGY","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82836654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sharn Shelley, R. James, S. Eustace, Emma L. J. Eyre, J. Tallis
This study examined the effect of stimulation frequency (140, 200, 230 and 260 Hz) on isometric force, work loop (WL) power, and the fatigue resistance of extensor digitorum longus (EDL) muscle (n=32), isolated from 8-10-week-old CD-1 female mice. Stimulation frequency had significant effects on isometric properties of isolated mouse EDL, whereby increasing stimulation frequency evoked increased isometric force, quicker activation, and prolonged relaxation (P <0.047), until 230 Hz and above, thereafter force and activation did not differ (P >0.137). Increasing stimulation frequency increased maximal WL power output (P <0.001; 140 Hz, 71.3±3.5; 200 Hz, 105.4±4.1; 230 Hz, 115.5±4.1; 260 Hz, 121.1±4.1 W.kg-1), but resulted in significantly quicker rates of fatigue during consecutive WL's (P <0.004). WL shapes indicate impaired muscle relaxation at the end of shortening and subsequent increased negative work appeared to contribute to fatigue at 230 and 260 Hz, but not at lower stimulation frequencies. Cumulative work was unaffected by stimulation frequency, except at the start of fatigue protocol where 230 and 260 Hz produced more work than 140 Hz (P <0.039). We demonstrate that stimulation frequency affects force, power, and fatigue, but effects are not uniform between different assessments of contractile performance. Therefore, future work examining contractile properties of isolated skeletal muscle should consider increasing stimulation frequency beyond that needed for maximal force when examining maximal power but utilise a sub-maximal stimulation frequency for fatigue assessments to avoid high degree of negative work atypical of in vivo function.
{"title":"Effect of stimulation frequency on force, power, and fatigue of isolated mouse extensor digitorum longus muscle.","authors":"Sharn Shelley, R. James, S. Eustace, Emma L. J. Eyre, J. Tallis","doi":"10.1242/jeb.243285","DOIUrl":"https://doi.org/10.1242/jeb.243285","url":null,"abstract":"This study examined the effect of stimulation frequency (140, 200, 230 and 260 Hz) on isometric force, work loop (WL) power, and the fatigue resistance of extensor digitorum longus (EDL) muscle (n=32), isolated from 8-10-week-old CD-1 female mice. Stimulation frequency had significant effects on isometric properties of isolated mouse EDL, whereby increasing stimulation frequency evoked increased isometric force, quicker activation, and prolonged relaxation (P <0.047), until 230 Hz and above, thereafter force and activation did not differ (P >0.137). Increasing stimulation frequency increased maximal WL power output (P <0.001; 140 Hz, 71.3±3.5; 200 Hz, 105.4±4.1; 230 Hz, 115.5±4.1; 260 Hz, 121.1±4.1 W.kg-1), but resulted in significantly quicker rates of fatigue during consecutive WL's (P <0.004). WL shapes indicate impaired muscle relaxation at the end of shortening and subsequent increased negative work appeared to contribute to fatigue at 230 and 260 Hz, but not at lower stimulation frequencies. Cumulative work was unaffected by stimulation frequency, except at the start of fatigue protocol where 230 and 260 Hz produced more work than 140 Hz (P <0.039). We demonstrate that stimulation frequency affects force, power, and fatigue, but effects are not uniform between different assessments of contractile performance. Therefore, future work examining contractile properties of isolated skeletal muscle should consider increasing stimulation frequency beyond that needed for maximal force when examining maximal power but utilise a sub-maximal stimulation frequency for fatigue assessments to avoid high degree of negative work atypical of in vivo function.","PeriodicalId":22458,"journal":{"name":"THE EGYPTIAN JOURNAL OF EXPERIMENTAL BIOLOGY","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82048626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Callum S Mcdiarmid, L. L. Hurley, Madiline Le Mesurier, Andrew C Blunsden, S. Griffith
ABSTRACT Sperm traits can influence fertilisation success, but there is still much we do not understand about sperm condition dependence, that is, how much sperm traits depend on the male's energy acquisition and allocation. This is especially pronounced in avian taxa, despite extensive observational studies and sampling in wild populations. In this study, we collected sperm samples before and after experimentally reducing diet quality of wild-derived captive zebra finches in small mixed-sex groups, which we compared with individuals on a control diet. We measured the length of sperm components (head, midpiece, flagellum and total sperm length), the proportion of sperm with normal morphology, the proportion of sperm that were progressively motile and sperm swimming velocity (curvilinear velocity; VCL). The only sperm trait we found to be impacted by reduced diet quality was a significant decrease in sperm midpiece length. This is consistent with emerging evidence in other non-model systems, as well the fact that diet can alter mitochondrial density and structure in other tissue types. There was also a significant decrease in sperm velocity and the proportion of motile sperm over the course of the experiment for both experimental groups (i.e. unrelated to diet). This decrease in sperm velocity with largely unchanged sperm morphology emphasizes that there are other important determinants of sperm velocity, likely including seminal fluid composition.
{"title":"The impact of diet quality on the velocity, morphology and normality of sperm in the zebra finch Taeniopygia guttata","authors":"Callum S Mcdiarmid, L. L. Hurley, Madiline Le Mesurier, Andrew C Blunsden, S. Griffith","doi":"10.1242/jeb.243715","DOIUrl":"https://doi.org/10.1242/jeb.243715","url":null,"abstract":"ABSTRACT Sperm traits can influence fertilisation success, but there is still much we do not understand about sperm condition dependence, that is, how much sperm traits depend on the male's energy acquisition and allocation. This is especially pronounced in avian taxa, despite extensive observational studies and sampling in wild populations. In this study, we collected sperm samples before and after experimentally reducing diet quality of wild-derived captive zebra finches in small mixed-sex groups, which we compared with individuals on a control diet. We measured the length of sperm components (head, midpiece, flagellum and total sperm length), the proportion of sperm with normal morphology, the proportion of sperm that were progressively motile and sperm swimming velocity (curvilinear velocity; VCL). The only sperm trait we found to be impacted by reduced diet quality was a significant decrease in sperm midpiece length. This is consistent with emerging evidence in other non-model systems, as well the fact that diet can alter mitochondrial density and structure in other tissue types. There was also a significant decrease in sperm velocity and the proportion of motile sperm over the course of the experiment for both experimental groups (i.e. unrelated to diet). This decrease in sperm velocity with largely unchanged sperm morphology emphasizes that there are other important determinants of sperm velocity, likely including seminal fluid composition.","PeriodicalId":22458,"journal":{"name":"THE EGYPTIAN JOURNAL OF EXPERIMENTAL BIOLOGY","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77816758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Rico-Guevara, Laura Echeverri-Mallarino, C. J. Clark
Vertebrates communicate through a wide variety of sounds, but few mechanisms of sound production, besides vocalization, are well understood. During high-speed dives, male trainbearer hummingbirds (Lesbia spp.) produce a repeated series of loud snaps. Hypotheses for these peculiar sounds include employing their elongated tails and/or their wings striking each other. Each snap to human ears seems like a single acoustic event, but sound recordings revealed that each snap is actually a couplet of impulsive, atonal sounds produced ∼13 ms apart. Analysis of high-speed videos refutes these previous hypotheses, and furthermore suggests that this sonation is produced by a within-wing mechanism- each instance of a sound coincided with a distinctive pair of deep wingbeats (with greater stroke amplitude, measured for one display sequence). Across many displays, we found a tight alignment between a pair of stereotyped deep wingbeats (in contrast to shallower flaps across the rest of the dive) and patterns of snap production, evidencing a 1:1 match between these sonations and stereotyped kinematics. Other birds including owls and poorwills are reported to produce similar sounds, suggesting that this mechanism of sound production could be somewhat common within birds, yet its physical acoustics remains poorly understood.
{"title":"Oh, snap! A within-wing sonation in black-tailed trainbearers.","authors":"A. Rico-Guevara, Laura Echeverri-Mallarino, C. J. Clark","doi":"10.1242/jeb.243219","DOIUrl":"https://doi.org/10.1242/jeb.243219","url":null,"abstract":"Vertebrates communicate through a wide variety of sounds, but few mechanisms of sound production, besides vocalization, are well understood. During high-speed dives, male trainbearer hummingbirds (Lesbia spp.) produce a repeated series of loud snaps. Hypotheses for these peculiar sounds include employing their elongated tails and/or their wings striking each other. Each snap to human ears seems like a single acoustic event, but sound recordings revealed that each snap is actually a couplet of impulsive, atonal sounds produced ∼13 ms apart. Analysis of high-speed videos refutes these previous hypotheses, and furthermore suggests that this sonation is produced by a within-wing mechanism- each instance of a sound coincided with a distinctive pair of deep wingbeats (with greater stroke amplitude, measured for one display sequence). Across many displays, we found a tight alignment between a pair of stereotyped deep wingbeats (in contrast to shallower flaps across the rest of the dive) and patterns of snap production, evidencing a 1:1 match between these sonations and stereotyped kinematics. Other birds including owls and poorwills are reported to produce similar sounds, suggesting that this mechanism of sound production could be somewhat common within birds, yet its physical acoustics remains poorly understood.","PeriodicalId":22458,"journal":{"name":"THE EGYPTIAN JOURNAL OF EXPERIMENTAL BIOLOGY","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78130280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Crustacean filter feeders capture oil droplets with the use of their ramified appendages. These appendages behave as paddles or sieves, based on the system's Reynolds number. Here we used high-speed videography, scanning electron microscopy and fluid mechanics to study the capturing mechanisms of crude oil droplets and the filtering appendage's wettability by two species of barnacles (Balanus glandula and Balanus crenatus) and of the freshwater cladoceran Daphnia magna. Our results show that barnacles appendages will behave as paddles and capture droplets in their boundary layers at low Reynolds number. At high Reynolds number, droplets are most likely to be captured via direct interception. There is an intermediate range of Reynolds number where droplets can be captured by both mechanisms at the same time. Daphnia magna captures droplets in the boundary layers of the third and fourth pair of thoracic legs with a metachronal motion of the appendages. All studied surfaces were revealed to be highly lipophobic, demonstrating captured oil droplets with high contact angles. We also discuss implications of such capture mechanisms and wettability on potential ingestion of crude oil by filter feeders. These results further our understanding of the capture of crude oil by filter feeders, shedding light onto the main entry point of oil in the marine food webs.
{"title":"The capture of crude oil droplets by filter feeders at high and low Reynolds numbers.","authors":"Francis Letendre, C. Cameron","doi":"10.1242/jeb.243819","DOIUrl":"https://doi.org/10.1242/jeb.243819","url":null,"abstract":"Crustacean filter feeders capture oil droplets with the use of their ramified appendages. These appendages behave as paddles or sieves, based on the system's Reynolds number. Here we used high-speed videography, scanning electron microscopy and fluid mechanics to study the capturing mechanisms of crude oil droplets and the filtering appendage's wettability by two species of barnacles (Balanus glandula and Balanus crenatus) and of the freshwater cladoceran Daphnia magna. Our results show that barnacles appendages will behave as paddles and capture droplets in their boundary layers at low Reynolds number. At high Reynolds number, droplets are most likely to be captured via direct interception. There is an intermediate range of Reynolds number where droplets can be captured by both mechanisms at the same time. Daphnia magna captures droplets in the boundary layers of the third and fourth pair of thoracic legs with a metachronal motion of the appendages. All studied surfaces were revealed to be highly lipophobic, demonstrating captured oil droplets with high contact angles. We also discuss implications of such capture mechanisms and wettability on potential ingestion of crude oil by filter feeders. These results further our understanding of the capture of crude oil by filter feeders, shedding light onto the main entry point of oil in the marine food webs.","PeriodicalId":22458,"journal":{"name":"THE EGYPTIAN JOURNAL OF EXPERIMENTAL BIOLOGY","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81798683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Insects have a large ratio of surface area to volume because of their small size; thus, they face the potential for desiccation in the terrestrial environment. Nonetheless, they constitute over half of identified species and their success on land can be attributed, in part, to adaptations that limit water loss and allow for effective gains of water from food, fluids or atmospheric water vapour. Reduction of water loss from the gut involves sophisticated mechanisms of ion recycling and water recovery by epithelia of the Malpighian tubules and hindgut. Water loss across the body surface is greatly reduced by the evolution of very thin but highly impermeable lipid-rich layers in the epicuticle. Respiratory water loss can be reduced through effective spiracular control mechanisms and by mechanisms for convective rather than diffusive gas exchange. In addition to extracting water from food sources, some insects are capable of absorption of atmospheric water vapour through processes that have evolved independently in multiple groups.
{"title":"A perspective on insect water balance.","authors":"M. O'Donnell","doi":"10.1242/jeb.242358","DOIUrl":"https://doi.org/10.1242/jeb.242358","url":null,"abstract":"Insects have a large ratio of surface area to volume because of their small size; thus, they face the potential for desiccation in the terrestrial environment. Nonetheless, they constitute over half of identified species and their success on land can be attributed, in part, to adaptations that limit water loss and allow for effective gains of water from food, fluids or atmospheric water vapour. Reduction of water loss from the gut involves sophisticated mechanisms of ion recycling and water recovery by epithelia of the Malpighian tubules and hindgut. Water loss across the body surface is greatly reduced by the evolution of very thin but highly impermeable lipid-rich layers in the epicuticle. Respiratory water loss can be reduced through effective spiracular control mechanisms and by mechanisms for convective rather than diffusive gas exchange. In addition to extracting water from food sources, some insects are capable of absorption of atmospheric water vapour through processes that have evolved independently in multiple groups.","PeriodicalId":22458,"journal":{"name":"THE EGYPTIAN JOURNAL OF EXPERIMENTAL BIOLOGY","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78061597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-01Epub Date: 2022-04-19DOI: 10.1242/jeb.243817
Jessica L Tingle, Brian M Sherman, Theodore Garland
The movement of limbless terrestrial animals differs fundamentally from that of limbed animals, yet few scaling studies of their locomotor kinematics and morphology are available. We examined scaling and relations of morphology and locomotion in sidewinder rattlesnakes (Crotalus cerastes). During sidewinding locomotion, a snake lifts sections of its body up and forward while other sections maintain static ground contact. We used high-speed video to quantify whole-animal speed and acceleration; the height to which body sections are lifted; and the frequency, wavelength, amplitude and skew angle (degree of tilting) of the body wave. Kinematic variables were not sexually dimorphic, and most did not deviate from isometry, except wave amplitude. Larger sidewinders were not faster, contrary to many results from limbed terrestrial animals. Free from the need to maintain dynamic similarity (because their locomotion is dominated by friction rather than inertia), limbless species may have greater freedom to modulate speed independently of body size. Path analysis supported: (1) a hypothesized relationship between body width and wavelength, indicating that stouter sidewinders form looser curves; (2) a strong relationship between cycle frequency and whole-animal speed; and (3) weaker effects of wavelength (positive) and amplitude (negative) on speed. We suggest that sidewinding snakes may face a limit on stride length (to which amplitude and wavelength both contribute), beyond which they sacrifice stability. Thus, increasing frequency may be the best way to increase speed. Finally, frequency and skew angle were correlated, a result that deserves future study from the standpoint of both kinematics and physiology.
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