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Musculoskeletal comparison of the pectoral fin in mudskippers (Gobiidae: Oxudercinae) 弹涂鱼胸鳍肌肉骨骼的比较（虾蛄科：弹涂鱼科）。

IF 1.6 3区生物学

Zoology Pub Date : 2025-09-01 DOI: 10.1016/j.zool.2025.126295

Lam V. Nguyen , Phuong T. Dang , Van V. Mai , Loi X. Tran

{"title":"Musculoskeletal comparison of the pectoral fin in mudskippers (Gobiidae: Oxudercinae)","authors":"Lam V. Nguyen , Phuong T. Dang , Van V. Mai , Loi X. Tran","doi":"10.1016/j.zool.2025.126295","DOIUrl":"10.1016/j.zool.2025.126295","url":null,"abstract":"<div><div>Shifting of the locomotor mode from an aquatic thrust to a ground reaction force enabled vertebrates moving on land, which happened at the same time as fin-to-limb evolution. Early stages of this evolution are little known due to scattered fossil records. Oxudercine gobies, exhibiting the full spectrum of terrestriality and terrestrial locomotor behavior, provide a unique window to understand how the form and function of the pectoral fins were modified during the water-to-land transition. In the present study, the musculoskeletal system of pectoral fins of three mudskippers [<em>Oxuderces nexipinnis</em> (low terrestrial), <em>Scartelaos histophorus</em> (moderate terrestrial), and <em>Periophthalmodon septemradiatus</em> (high terrestrial)] and the out-group species (<em>Oxyeleotris urophthalmus</em>) were examined. There are some anatomical modifications endowing crutching on land including: the robust and triangular cleithrum; the stiff and elongated radials and fin rays; the development of the coracoid process, the radial process, and the coraco-radialis; the two hinge-like structures; the differentiated muscular system inclining in various angles; and well-developed adductor muscles. These configurations are correlated with the degree of terrestriality. Of these anatomical modifications, the presence of the coracoid process, the radial process, and the coraco-radialis could endow terrestrial movement in early oxudercine gobies. In addition, fin rays of early oxudercine gobies could prevent them from sinking into the unconsolidated substrates which could be analogous to the condition in sarcopterygian fishes. In general, this study shows the gradual evolution of the muscular and skeletal systems of the pectoral fins in the oxudercine gobies during water-to-land transitions.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"172 ","pages":"Article 126295"},"PeriodicalIF":1.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145208877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Flip or flop? Behavioral response to stranding in fish representing six teleost orders 翻转还是翻转？鱼对搁浅的行为反应代表六目硬骨鱼

IF 1.6 3区生物学

Zoology Pub Date : 2025-09-01 DOI: 10.1016/j.zool.2025.126294

Michael R. Minicozzi , Shannon Hansen , Michael Akland , Ana Braga , Owen Kyle , C. Loren Buck , Miriam Ashley-Ross , Alice C. Gibb

{"title":"Flip or flop? Behavioral response to stranding in fish representing six teleost orders","authors":"Michael R. Minicozzi , Shannon Hansen , Michael Akland , Ana Braga , Owen Kyle , C. Loren Buck , Miriam Ashley-Ross , Alice C. Gibb","doi":"10.1016/j.zool.2025.126294","DOIUrl":"10.1016/j.zool.2025.126294","url":null,"abstract":"<div><div>Aquatic and amphibious fishes produce a variety of behaviors when stranded on land, including a ballistic movement called a tail-flip jump. Although recent studies have examined jump performance (distance) in several cyprinodontiform species, less is known about the diversity of behaviors produced by teleosts when stranded on land. Here, seven species from four major teleost lineages (individual n = 4–12) were manually stranded in a terrestrial arena for two-minute trials. From videos of the trials, the number of jumps, flops (movements <1 body length), displacement (total and mean), latency (time to onset of movement), and percent time moving were quantified for each individual. A principal components analysis of these variables was used to define four “behavioral spaces:” species that produced effective displacement and spent the majority of the trial period moving (<em>Danio</em>); species that produced less effective displacement and spent the majority of the trial period moving (<em>Pseudomugil</em>); species that produced less effective displacement and spent little time moving (<em>Umbra</em>); and species that produced effective displacement, but spent little time moving (<em>Kryptolebias</em>). Based on the literature and metabolic data collected for this study, it appears that the ability to extract oxygen from air (vs. water) predicts the amount of time spent moving when stranded on land. Air-breathing fishes appear to adopt a “wait and see strategy,” while species that lack the ability to breathe air move immediately and frequently, likely an attempt to return to the water as quickly as possible.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"172 ","pages":"Article 126294"},"PeriodicalIF":1.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145158775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Bite force variation in the European pond turtle: Role of morphology, strength, body condition and population of origin 欧洲塘龟咬合力的变化：形态、力量、身体状况和种群起源的作用。

IF 1.6 3区生物学

Zoology Pub Date : 2025-09-01 DOI: 10.1016/j.zool.2025.126296

Marko Maričić, Vukašin Bjelica, Ana Golubović

{"title":"Bite force variation in the European pond turtle: Role of morphology, strength, body condition and population of origin","authors":"Marko Maričić, Vukašin Bjelica, Ana Golubović","doi":"10.1016/j.zool.2025.126296","DOIUrl":"10.1016/j.zool.2025.126296","url":null,"abstract":"<div><div>Bite force is a biomechanical trait that serves as a valuable proxy for assessing ecological interactions, feeding specialisations, and evolutionary pressures. Chelonians are a unique model system in studies of masticatory performances due to their akinetic skull and lack of teeth. It is known that body size, head morphology and sex-related differences influence bite performance of some chelonian species. In this study, we investigated the variation in bite force within and among five populations of the European pond turtle (<em>Emys orbicularis</em>) in Serbia. We examined relationship of bite force with phenotypic traits such as body size, head dimensions, body condition and muscle strength, as well as body temperature and seasonality. Bite force was measured in the field (N = 209) with an adapted digital force sensor. Our results showed significant differences in bite force across populations, suggesting that local ecological conditions may play a crucial role in shaping bite performance. In particular, turtles from more diverse and structurally complex environments, and turtles sharing their habitat with non-native pond sliders (<em>Trachemys scripta</em> ssp.) exhibited higher bite forces. We also detected a positive association between bite force and maximal pulling force, volumetric body condition index, body size and head height. Surprisingly, sex, cloacal temperature and seasonality were not significant predictors of bite force. Despite the challenges of measuring maximal performance under field conditions, our findings illustrate how variation in functional traits can reflect both intrinsic factors and ecological context, with implications for the study of biomechanical adaptations across animal taxa.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"172 ","pages":"Article 126296"},"PeriodicalIF":1.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145208927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Reproductive investment in the knifefish Brachyhypopomus occidentalis 西方短刀鱼的生殖投资

IF 1.6 3区生物学

Zoology Pub Date : 2025-08-19 DOI: 10.1016/j.zool.2025.126293

Marangaby Mahamat , Luis F. De León , Mery L. Martínez

{"title":"Reproductive investment in the knifefish Brachyhypopomus occidentalis","authors":"Marangaby Mahamat , Luis F. De León , Mery L. Martínez","doi":"10.1016/j.zool.2025.126293","DOIUrl":"10.1016/j.zool.2025.126293","url":null,"abstract":"<div><div>An organism's ability to produce viable offspring, or reproductive fitness, often depends on several environmental and ecological factors such as temperature, food availability and predation. Changes in these factors can act as stressors, forcing organisms to optimize energy allocation, resulting in trade-offs. In this study, we investigate the reproductive biology of the South American electric fish <em>Brachyhypopomus occidentalis</em>, examining whether perceived predation risk can influence reproductive output. We sampled four populations during the reproductive season at two pairs of sites with differing levels of predation risk across independent river drainages. We assessed several traits including sexual dimorphism and reproductive traits such as gonad mass, fecundity, and gamete morphology parameters. Our findings reveal physical sexual dimorphism, with males being larger and heavier than females. Individuals from low predation risk sites were significantly larger, had heavier gonads, and exhibited higher gonadosomatic indices. Females from low predation risk sites invested more in gonad development, showing increased relative and absolute fecundities and higher oocyte counts at each maturity stage. Collectively, our results strongly suggest that predation risk plays a significant role in shaping reproductive strategies in electric fishes and also underscore how ecological pressures can drive variation in reproductive investment across fish populations.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"172 ","pages":"Article 126293"},"PeriodicalIF":1.6,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Jaw muscle architecture in the greater rhea (Rhea americana): Morphological patterns and postnatal ontogeny in an herbivorous bird 美洲大美洲豹的颚肌结构：一种食草鸟类的形态模式和出生后个体发育

IF 1.6 3区生物学

Zoology Pub Date : 2025-06-14 DOI: 10.1016/j.zool.2025.126283

Mariana B.J. Picasso , María Clelia Mosto , Alejandro M. Tudisca , Laura M. Biondi

{"title":"Jaw muscle architecture in the greater rhea (Rhea americana): Morphological patterns and postnatal ontogeny in an herbivorous bird","authors":"Mariana B.J. Picasso , María Clelia Mosto , Alejandro M. Tudisca , Laura M. Biondi","doi":"10.1016/j.zool.2025.126283","DOIUrl":"10.1016/j.zool.2025.126283","url":null,"abstract":"<div><div>The jaw muscle architecture is crucial for understanding how muscle morphology influences diet and feeding behavior in birds, yet ontogenetic scaling patterns and their characteristics in herbivorous species remain understudied. This study examines the physiological cross-sectional area (PCSA) and fiber length of the jaw muscles in <em>Rhea americana</em>, an herbivorous bird whose chicks are insectivorous during early stages. The main jaw muscles of 19 <em>Rhea americana</em> specimens across four ontogenetic stages were analyzed, including the depressor mandibulae (a jaw depressor) and the adductor mandibulae externus, pseudotemporalis, and pterygoideus lateralis (primarily jaw adductors). Both architectural parameters showed a negative allometric scaling and only significant differences in PCSA were found between immature ages and between these and adulthood in certain adductor muscles. These variations suggest increasing force demands in adductor muscles as chicks transition from an insectivorous to an herbivorous diet. The lower PCSA in early-staged chicks reflects the reduced force required for insectivory, while the increasing PCSA with age enables force generation needed for detaching plants in adults. In comparison to other avian diets, the herbivory of greater rhea seems to be linked to a lower force-generating capacity in the adductor muscle group. This study contributes to expanding the knowledge on avian jaw musculature by exploring postnatal ontogenetic changes and their potential relationship with dietary shifts while providing morphological data that can serve as a comparative basis for understanding the link between diet and morphology in birds.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126283"},"PeriodicalIF":1.6,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144306973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Abdominal sensing of substrate vibrations in insects 昆虫腹部对基底振动的感应

IF 1.6 3区生物学

Zoology Pub Date : 2025-06-09 DOI: 10.1016/j.zool.2025.126282

Joscha A. Alt, Reinhard Lakes-Harlan

{"title":"Abdominal sensing of substrate vibrations in insects","authors":"Joscha A. Alt, Reinhard Lakes-Harlan","doi":"10.1016/j.zool.2025.126282","DOIUrl":"10.1016/j.zool.2025.126282","url":null,"abstract":"<div><div>Mechanosensation is a universal sensory modality and respective receptors in insects are located in all body parts. For perception of substrate vibrations, highly specialized sensory organs have evolved. In insects, the legs contain specialized vibration sensors, but insects also touch the substrate with other body parts, like their abdomen. Here, we used extracellular recordings from abdominal nerves to test for vibrational sensitivity in two evolutionarily distant insect species. Vibrational stimuli of defined frequencies (30 Hz – 10 kHz) and accelerations (0.01 – 10 m/s<sup>2</sup>) were applied to the caudal region of the abdomen while recording from nerves associated with mechanosensitive chordotonal organs. In the grasshopper <em>Schistocerca gregaria</em> (Forsskal), abdominal nerves are almost as sensitive to substrate vibrations as the leg nerves. In the cicada <em>Okanagana rimosa</em> (Say), the sensitivity of abdominal sense organs is even higher than that of the leg associated sense organs. In both species, their abdominal tympanate ears are also sensitive to substrate vibrations. The results show that chordotonal organs in the abdomen can significantly contribute to vibration perception in insects.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126282"},"PeriodicalIF":1.6,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144240619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Vertical transfer of bacterial symbionts via a placental analogue in the cyclostome bryozoan Patinella verrucaria (Stenolaemata): Ultrastructural and molecular evidence 细菌共生体在环状苔藓虫中的胎盘类似物垂直转移：超微结构和分子证据

IF 1.6 3区生物学

Zoology Pub Date : 2025-06-08 DOI: 10.1016/j.zool.2025.126281

M.A. Demidova , A.E. Vishnyakov , N.P. Karagodina , O.N. Kotenko , U.A. Nekliudova , E.A. Bogdanov , A.N. Ostrovsky

{"title":"Vertical transfer of bacterial symbionts via a placental analogue in the cyclostome bryozoan Patinella verrucaria (Stenolaemata): Ultrastructural and molecular evidence","authors":"M.A. Demidova , A.E. Vishnyakov , N.P. Karagodina , O.N. Kotenko , U.A. Nekliudova , E.A. Bogdanov , A.N. Ostrovsky","doi":"10.1016/j.zool.2025.126281","DOIUrl":"10.1016/j.zool.2025.126281","url":null,"abstract":"<div><div>Symbiotic associations with prokaryotes are common among marine filter-feeding invertebrates. In the almost exclusively colonial phylum Bryozoa, however, such associations have only been recorded in some species of the order Cheilostomata (class Gymnolaemata). Here we describe for the first time symbiotic bacteria in the colonies, larvae and developing ancestrulae of the bryozoan <em>Patinella verrucaria</em> from the order Cyclostomata (class Stenolaemata) using transmission electron and fluorescent microscopy. Ultrastructural and molecular data suggest the existence of two distinct bacterial species, both from the family Rhodobacteraceae. The presence of bacteria in all three stages of the bryozoan life cycle indicates a vertical transfer of symbionts. Both intracellular and free bacteria were recorded in the colonies, being presumably transported by amoebocytes from autozooids to the colonial incubation chamber. The bacteria are accumulated in the placental analogue and in associated cells surrounding developing embryos and larvae, and are presumably transmitted to the mature ciliated larvae during rupture of the placenta facilitated by the movements of their cilia before and/or during larval release. Thus, the nourishing function of the placenta is complemented by the symbiont transfer, which can be regarded as an example of extension of functions. This is the first example of a placenta providing bacterial infection to the progeny in invertebrates.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126281"},"PeriodicalIF":1.6,"publicationDate":"2025-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Cryptic anatomical adaptive peak shifts and transitions along the body elongation continuum in zoarcoid fishes zoarcoid鱼类沿身体延伸连续体的隐解剖适应性峰移和过渡

IF 1.6 3区生物学

Zoology Pub Date : 2025-06-08 DOI: 10.1016/j.zool.2025.126280

Summer E. Duba, David C. Collar

{"title":"Cryptic anatomical adaptive peak shifts and transitions along the body elongation continuum in zoarcoid fishes","authors":"Summer E. Duba, David C. Collar","doi":"10.1016/j.zool.2025.126280","DOIUrl":"10.1016/j.zool.2025.126280","url":null,"abstract":"<div><div>Body elongation is a major feature of ray-finned fish evolution. Elongate body shapes have arisen repeatedly across lineages and led to a phylogenetically diverse array of eel-like fishes. Despite apparent convergence in overall shape, independent elongation events have occurred through a diversity of skeletal anatomical changes, suggesting variability in underlying developmental, functional, and ecological shifts. It is less clear, however, whether such diversity characterizes evolution in lineages following elongation. In this study, we show that, even within a predominantly elongate radiation of teleost fishes, the Zoarcoidei (eelpouts, pricklebacks, and others), a variety of anatomical shifts have occurred, and they exhibit a complex relationship with body shape. We measured dimensions of the cranial and axial skeleton as well as overall body shape from 71 species representing 12 of 14 recognized zoarcoid families, and we fit multi-optimum adaptive evolutionary (Ornstein-Uhlenbeck) models to these data. We estimated a moderately elongate ancestral optimum for Zoarcoidei that was retained in most lineages. Still, we identified three peak shifts to highly elongate body shapes, which differed in associated anatomical changes. In addition, we detected multiple cryptic anatomical peak shifts in which transitions in cranial and axial skeletal anatomy occurred in lineages that retained the ancestral body shape optimum. Altogether, our results reveal a hidden level of morphological evolution in elongate fishes, suggesting that similarity in body shape belies diverse ecological demands and varied functional capacities.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126280"},"PeriodicalIF":1.6,"publicationDate":"2025-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Variations of larval ommatidia in four species of Bittacidae (Insecta: Mecoptera) 四种蠓科幼虫小孔虫的变异（昆虫纲：鞘翅目）

IF 1.6 3区生物学

Zoology Pub Date : 2025-06-07 DOI: 10.1016/j.zool.2025.126279

Wan-Ruo Ma, Jia-Li Bai, Bao-Zhen Hua

{"title":"Variations of larval ommatidia in four species of Bittacidae (Insecta: Mecoptera)","authors":"Wan-Ruo Ma, Jia-Li Bai, Bao-Zhen Hua","doi":"10.1016/j.zool.2025.126279","DOIUrl":"10.1016/j.zool.2025.126279","url":null,"abstract":"<div><div>The larvae of Bittacidae normally bear a pair of compound eyes on the lateral sides of the head. The compound eyes each are reported to consist of seven ommatidia. However, whether the eyes have variations in number among species and individuals remain unclear to date. Here, ommatidial variations of compound eyes were investigated in four species of Bittacidae larvae using light microscopy. The results show that the number of ommatidia remains constant for a larval eye across instars of the same larva, but numerical variations of ommatidia were found for different individuals and different species of Bittacidae. The compound eyes of larvae each consist of six to ten ommatidia in the most widely distributed <em>Bittacus cirratus</em> Tjeder, but are composed of seven to nine ommatidia in <em>B. planus</em> Cheng and <em>B. lii</em> Zhou, and seven to eight ommatidia in <em>Terrobittacus longisetus</em> Tan & Hua. Seven ommatidia are the most common number, likely representing the ground plan of larval compound eyes in Bittacidae. The distribution patterns of ommatidia can be categorized into five types. The significance of larval ommatidial variation of Bittacidae is briefly discussed with behavior of larvae and evolution of visual organs of holometabolous larvae.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126279"},"PeriodicalIF":1.6,"publicationDate":"2025-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Morphology of the circulatory system in Caobangia billeti Giard, 1893 (Annelida, Sabellidae) 1893年曹班贾（Caobangia billeti Giard）循环系统的形态学研究（环节动物，Sabellidae）

IF 1.6 3区生物学

Zoology Pub Date : 2025-05-08 DOI: 10.1016/j.zool.2025.126272

Varvara I. Krolenko , Glafira D. Kolbasova , Alexander B. Tzetlin

{"title":"Morphology of the circulatory system in Caobangia billeti Giard, 1893 (Annelida, Sabellidae)","authors":"Varvara I. Krolenko , Glafira D. Kolbasova , Alexander B. Tzetlin","doi":"10.1016/j.zool.2025.126272","DOIUrl":"10.1016/j.zool.2025.126272","url":null,"abstract":"<div><div><em>Caobangia billeti</em> is an aberrant shell-burrowing annelid with a phoronid-like body plan and U-shaped digestive tract, an anterior anus on the dorsal side near the head, and reduced metamerism. The segmental dissepiments in <em>C. billeti</em> are absent, but the circulatory system is complex and consists of numerous lacunae and vessels. We asked the question how this modified circulatory system compares to that of other Sabellida. To that end, we collected <em>C. billeti</em> from the type locality and for the first time provide a detailed morphological investigation of these worms using both electron (TEM) and light microscopy. Our data show that, despite the significant modification of the body plan, the circulatory system is generally similar to that of other Sabellida representatives. The central circulatory system includes dorsal and ventral vessels, circular segmental vessels, and the peri-intestinal sinus, while the peripheral system includes the vessels of the branchial crown, collar vessels and esophageal plexuses, and transseptal vessels. However, compared to other representatives of the order Sabellida this species possesses four paired lateroventral vessels instead of two, and extravasal rather than intravasal hematopoietic tissue. The abdomen of <em>C. billeti</em> has lost all internal metameric structures, except segmental vessels, the number of which coincides with the number of uncinial tori. The direction of blood flow was reconstructed using vital and morphological observations. There are no specialized propulsatory organs, but all vessels pulsate, except for the branchial vessels, which are passively filled with blood. In the circulatory system, the direction of blood flow can be reversed (from the head to the back of the body inside the dorsal vessel and vice versa ventrally), which has not previously been described for other Sabellida.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126272"},"PeriodicalIF":1.6,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144071494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0