Measuring the effects of morphology on performance, and performance on fitness, is necessary to gain a full picture of selection, adaptation, ecology, and evolution. The performance of an organism's feeding apparatus, of which teeth are an integral part, has obvious implications for its fitness and survival. Extant shark teeth encompass a wide variety of shapes, and are often ascribed qualitative functions without any biomechanical testing, employing terminology such as gripping, piercing, crushing, cutting, or tearing. Additionally, teeth also comprise the vast majority of the fossil record of sharks. Therefore to understand the evolution of the shark feeding mechanism, we must understand the contribution of all parts of the feeding apparatus, including the teeth. Performance testing of extant and extinct shark teeth, nanoindentation of shark teeth, finite element analysis of tooth morphology, and phylogenetically informed analyses of shark tooth morphology and ecology were employed to elucidate the relationship between performance, ecology, and evolution. Performance testing of teeth in puncture and draw revealed few morphological patterns, indicating that most morphologies are functionally equivalent. Finite element modeling of teeth in puncture, draw, and holding showed that shark teeth are structurally strong and unlikely to fail during feeding. Evolutionary analyses of tooth shape and ecology showed no relationship between morphology, habitat, and diet. These results have significant implications for the shark paleontology, where the shapes of shark teeth are used to make assumptions about ecology and evolution.

(1) Hatchery-reared Florida largemouth bass, Micropterus salmoides floridanus, feed on inert pellet food while their wild counterparts capture elusive prey. Differences in levels of prey elusivity often mandate the use of alternate methods of prey capture and are accompanied by a related phenotypic change. (2) This study investigates (a) differences between the prey capture kinematics and strike modes of hatchery and wild juvenile Florida largemouth bass raised on pellets and live prey, and (b) whether elusivity-based variation in prey capture translates to a phenotypic and functional change during skull development. (3) Analysis of high-speed videography demonstrates that wild bass capture live prey with very rapid movements and large excursions. Hatchery bass of the same age, raised and feeding on pellets, however, used slower kinematics with smaller excursions, yielding strikes with a higher degree of suction. (4) Capture events of hatchery bass fed live prey for the first time were characterized by movements that were faster than their wild counterparts, but had smaller excursion measurements and resulted in a decreased level of capture success. After five exposures to elusive mosquito fish, hatchery bass adapted their behaviors to capture prey at the kinematic level of wild bass. (5) The developmental pattern of the skull was conserved between hatchery and wild bass until 80-99mm TL. At this point, wild bass quickly developed morphological changes of the jaw apparatus including a more fusiform head and elongated jaw structures. Natural development in hatchery bass, however, was retarded at this size. Post-release, the skulls of hatchery fish converged towards those of wild bass by 135mm TL. Despite this variation in skull development, no theoretical advantage in food capture was found between these two groups. (6) It is likely that a lack of experience in live prey capture might constrain hatchery bass from utilizing the total functional potential of their specialized morphology, and therefore, exposure to elusive prey should be enforced in rearing-techniques of hatchery fishes in order to improve the low post-stock survival rates of this species.

<p>The Superfamily Strophomenoidea is a very diverse group of brachiopods in the Early Palaeozoic. In the Silurian succession on Gotland, they are among the most easily identifiable, and commonly found fossils. However, there are few detailed studies of this group from Gotland, and no new strophomenide taxa have been described from this area since 1869. The life habits of strophomenides are also poorly understood, partly because their morphology differs greatly from that of living brachiopods. </p><p>The succession on Gotland yielded 27 species belonging to the Strophomenoidea, of which two species and two subspecies are new. The remaining species have been described earlier from Gotland or Great Britain. The most important group is the Leptaeninae, which occurs commonly throughout the entire succession on Gotland. Five species (one new), two new subspecies and two taxa treated under open nomenclature were found. <i>Leptaena rhomboidalis</i> and <i>Lepidoleptaena poulseni</i> were specialized for life in shallow water environments, retaining a large apical pedicle; the remaining leptaenines were ambitopic. The Furcitellininae is represented by three genera comprising six species, of which only one persisted into the Ludlow. All were ambitopic, except <i>Pentlandina loveni</i>, which was specialized for high-energy environments. Six species of “strophodontids” from Gotland, belonging to the Leptostrophidae, the Strophodontidae and the Shaleriidae, share a shallow-bodied, variably concavo-convex shell with costellate ornament. <i>Mesoleptostrophia</i> and <i>Brachyprion</i> (<i>Brachyprion</i>) were long-ranged and ecologically tolerant, while <i>B.</i> (<i>Erinostrophia</i>), <i>Strophodonta</i> and <i>Shaleria</i> had short ranges and were ecologically specialized. The two earliest known cementing strophomenides occur on Gotland, and their hitherto unknown dorsal valves have been identified: <i>Liljevallia </i>was found to belong to the Douvillinidae. The cementing <i>Leptaenoidea silurica</i> was found to be conspecific with the ambitopic <i>Scamnomena rugata</i>; it was able to live ambitopically if removed from the substrate. The thickened dorsal valves allow reconstruction of its lophophore.</p>

The Superfamily Strophomenoidea is a very diverse group of brachiopods in the Early Palaeozoic. In the Silurian succession on Gotland, they are among the most easily identifiable, and commonly found fossils. However, there are few detailed studies of this group from Gotland, and no new strophomenide taxa have been described from this area since 1869. The life habits of strophomenides are also poorly understood, partly because their morphology differs greatly from that of living brachiopods. The succession on Gotland yielded 27 species belonging to the Strophomenoidea, of which two species and two subspecies are new. The remaining species have been described earlier from Gotland or Great Britain. The most important group is the Leptaeninae, which occurs commonly throughout the entire succession on Gotland. Five species (one new), two new subspecies and two taxa treated under open nomenclature were found. Leptaena rhomboidalis and Lepidoleptaena poulseni were specialized for life in shallow water environments, retaining a large apical pedicle; the remaining leptaenines were ambitopic. The Furcitellininae is represented by three genera comprising six species, of which only one persisted into the Ludlow. All were ambitopic, except Pentlandina loveni, which was specialized for high-energy environments. Six species of “strophodontids” from Gotland, belonging to the Leptostrophidae, the Strophodontidae and the Shaleriidae, share a shallow-bodied, variably concavo-convex shell with costellate ornament. Mesoleptostrophia and Brachyprion (Brachyprion) were long-ranged and ecologically tolerant, while B. (Erinostrophia), Strophodonta and Shaleria had short ranges and were ecologically specialized. The two earliest known cementing strophomenides occur on Gotland, and their hitherto unknown dorsal valves have been identified: Liljevallia was found to belong to the Douvillinidae. The cementing Leptaenoidea silurica was found to be conspecific with the ambitopic Scamnomena rugata; it was able to live ambitopically if removed from the substrate. The thickened dorsal valves allow reconstruction of its lophophore.

The relationship between form and function is often used to elucidate the biological role of a structure. Hammerhead sharks offer a unique opportunity to study form and function through phylogeny. Because sphyrnid sharks display a range of cranial morphologies this group can be used to address questions about the evolution of cranial design and investigate the effects of changes in head morphology on feeding structures and bite force. Geometric morphometrics, volumetric analyses, morphological dissections, and phylogenetic analyses of the cephalofoil were used to gain insight into changes in cranial design through evolutionary history. External morphometrics and internal volumetric analyses indicated that while the external shape of the cephalofoil and placement of the sensory structures is variable through evolutionary history, the volumes of the internal cranial elements do not change. Constructional constraints within the cephalofoil were confined to sensory structures while feeding morphology remained relatively unchanged. Analysis of the morphology and biomechanics of the feeding apparatus revealed that through phylogeny the feeding system does not change among sphyrnid species. However, size-removed bite force was lower than predicted for all sphyrnid species except Sphyrna mokarran. Despite differences in head morphology between sphyrnid and carcharhinid sharks, the feeding bauplan is conserved in sphyrnid sharks with few changes to the feeding structures. Instead the chondrocranial and sensory structures are modified around the relatively static feeding core. Finally, the durophagous S. tiburo was found to consume hard prey in a manner that is biomechanically and morphologically different from other durophagous fishes. Furthermore, the diet of S. tiburo is constrained by the properties of its preferred prey.

The elasmobranch fishes possess a remarkable diversity of feeding mechanisms for a group containing relatively few species (~1200). The three most prevalent of these mechanisms involve prey capture during which the predator overtakes its prey (ram), prey is drawn into the mouth of the predator (suction), and relatively stationary consumption of sessile or substrate affixed prey (biting). Biomechanical modeling of cranial force distributions, in situ bite performance trials, and kinematic analysis of prey capture behaviors were employed to identify morphological and behavioral specializations and constraints associated with these feeding mechanisms in lemon Negaprion brevirostris (ram), whitespotted bamboo Chiloscyllium plagiosum (suction), and horn Heterodontus francisci (biting) sharks. Biomechanical modeling of the forces generated by the cranial musculature was used to theoretically estimate the maximum bite force and mechanical loadings occurring throughout the hyostyl ic jaw suspension mechanisms of each species, characterized by suspensory hyomandibular cartilages between the back of the jaws and cranium and anterior ligamentous attachments. To assess the mechanical factors involved in the evolution of elasmobranch jaw suspension mechanisms, the feeding mechanism of the sharpnose sevengill shark Heptranchias perlo was modeled as well. Heptranchias perlo possesses an ancestral amphistylic jaw suspension mechanism including non-suspensory hyomandibular cartilages, a large post-orbital articulation between the jaws and cranium, and anterior ligamentous attachments. Theoretical estimates of maximum bite force were compared to voluntary bite forces measured during in situ bite performance trials. Voluntary bite force measurements allowed the quantification of discrete behavioral attributes of bite force application in each species. To further assess the behavioral specializations associated with these feeding mechanisms, high-speed digital videography w as used to analyze the prey capture cranial kinematics of species. Collectively, these analyses have developed a morphological and behavioral basis from which to understand the functional diversity of the ram, suction, and biting feeding mechanisms in elasmobranchs.

Os isópodos terrestres possuem uma cutícula protetora que mantém a forma corporal, permite locomoção e comunicação com o ambiente e protege contra dessecação, infecção e predação. Assim como nos demais crustáceos, a cutícula é composta por uma matriz orgânica que é mineralizada com cálcio. A cutícula é uma estrutura versátil que reflete adaptações ambientais e a ampla distribuição geográfica do grupo. Dessa forma, a ultraestrutura e a composição da cutícula variam entre espécies. Isópodos terrestres fazem mudas frequentes ao longo da vida para crescer e/ou renovar receptores de superfície, o que resulta em reabsorção e deposição cuticular constante. Esse grupo apresenta muda bifásica e deposição de placas de cálcio nos esternitos anteriores antes da ecdise como estratégia para reciclar o cálcio corporal. Estudos relacionados à cutícula nesse grupo contemplam a ultraestrutura, a composição e a deposição bem como o efeito de alguns fatores ambientais na muda. No entanto, poucos estudos exploram as ligações entre ecomorfologia e história de vida. Essa tese visa explorar diversos aspectos relacionados à cutícula e a muda de duas espécies neotropicais de isópodos terrestres. Atlantoscia floridana e Balloniscus glaber foram usados como modelo uma vez que são frequentemente encontrados nas mesmas localidades e diferem em tipo ecomorfológico e estratégias ambientais. No Capítulo I, foram exploradas as estruturas de superfície e a ultraestrutura da cutícula das duas espécies a fim de ver como as diferenças encontradas podem ser relacionadas à história de vida de cada espécie, utilizando técnicas de microscopia. As espécies diferiram em tipo e disposição das estruturas de superfície bem como em espessura e proporção de camadas da cutícula. De maneira geral, as diferenças das estruturas de superfície estão relacionadas à seleção de microhabitat e nicho ecológico. Características cuticulares ajudam a explicar o hábito endógeno de B. glaber e epígeo de A. floridana enquanto que as diferenças em ultraestrutura são relacionadas a estratégias comportamentais e tolerância ambiental. No Capítulo II, o efeito do cálcio alimentar no ciclo de muda das espécies foi testado. Para isso, dieta experimental e análise estrutural da cutícula foram realizadas a fim de entender como diferentes concentrações de cálcio alimentar interferem na duração do ciclo de muda. Peculiaridades na ecdise em A. floridana refletem morfologia específica do animal. A duração da intramuda foi maior em B. glaber assim como a sobrevivência média nos tratamentos. A duração do ciclo de muda foi influenciada pela concentração de cálcio; uma tendência a menor duração do ciclo com o aumento da concentração de cálcio foi observada em B. glaber, enquanto em A. floridana a diferença encontrada foi apenas entre o controle sem cálcio e os demais tratamentos. Não houve efeito da dieta no grau de mineralização ou na ultraestrutura em B. glaber. Independentemente do tratamento, a maior taxa de mortalidade em laboratório parece estar relacionada com o próprio processo de ecdise, com mortalidade acumulada de 20% do início da ecdise até o início da pós-muda para ambas as espécies. No Capítulo III, a secreção da cutícula durante a pré- e pós-muda muda foi observada utilizando microscopia de transmissão. A deposição seguiu o padrão observado para outros isópodos. Entretanto, grânulos eletrondensos presentes no espaço ecdisial durante a pré-muda são provavelmente constituídos de cálcio, sugerindo a reciclagem de cálcio diretamente da cutícula velha para a nova no mesmo segmento. Esses grânulos são depositados nas escamas na nova epicutícula antes da ecdise, sugerindo a presença de cálcio na superfície cuticular das espécies. Além disso, regiões sem a ultraestrutura típica encontrada na pós-muda indicam que há modificação na exocutícula após a ecdise uma vez que a expansão e endurecimento da nova cutícula apenas após a ecdise. De maneira geral, esse trabalho não apenas trouxe novas informações sobre a estrutura cuticular de duas espécies neotropicias, mas também contribuiu para esclarecer conexões entre ecomorfologia e requerimentos biológicos de isópodos terrestres. / Terrestrial isopods have a protective cuticle that maintains body shape, allows locomotion, enables communication with the environment and protects them against desiccation, infection and predation. As in all crustaceans, their cuticle is composed of an organic matrix that is mineralized with calcium. The cuticle is highly versatile reflecting adaptations to environmental conditions and large geographical distribution of this group. Therefore, cuticle ultrastructure and composition vary among species. Terrestrial isopods molt frequently throughout their lives in order to grow and/or renew surface receptors, resulting in constant cuticular resorption and deposition. In this group, this dynamics of cuticle formation is affected by the biphasic molt and by the calcium deposition on sternal deposits prior ecdysis, strategies to recycle body calcium. Studies related to cuticle on this group include ultrastructure, composition and deposition as well as effect of some environmental factors on molting. However, few studies explore connections of ecomorphology and life history of animals. This thesis aimed to explore various aspects of cuticle structure and molting using two Neotropical species of terrestrial isopods. Atlantoscia floridana and Balloniscus glaber were used as models since they are found in the same locations while differing in ecomorphology and behavioral strategies. In Chapter I, I explored the cuticle surface structures and ultrastructure of both species to see how their differences can be related to each species life history traits, using microscopy techniques. Species differed in surface structures type and disposition, as well as cuticle thickness and layer proportion. Overall, differences in surface structure are related to microhabitat selection and ecological niche. Cuticular features further explain the endogeic habit of B. glaber and epigeic habit of A. floridana, while differences in cuticle ultrastructure relate to behavioral strategies and environmental tolerance. Next, differences on molting cycle and environmental requirements were analyzed. In Chapter II, I tested the effects of dietary calcium on the molting cycle of both species. For that, artificial diet and structural analysis of the cuticle were used to understand how different concentrations of dietary calcium interfere with molt cycle duration. Peculiarities were observed during ecdysis in A. floridana and reflect to specific morphology of the species. Intramolt duration was longer for B. glaber as well as overall survivorship in treatments. Cycle duration was influenced by calcium concentration; a trend of shorter molt cycle length with increasing calcium concentration was observed for B. glaber, while in A. floridana, only difference between control without calcium and other treatments was observed. Degree of mineralization and cuticle ultrastructure of B. glaber showed no difference between treatments. Regardless of treatment or species, higher mortality rate under lab conditions seems to be related to the process of ecdysis itself, with cumulative mortality of 20% from the beginning of ecdysis until the beginning of postmolt. In Chapter III, I used transmission electron microscopy to analyze cuticle secretion in both species during pre- and postmolt stages. Cuticle deposition during premolt followed the same pattern as other terrestrial isopods. Nonetheless, electron dense granules present on the ecdysial space during premolt are likely calcium granules, suggesting the recycling of calcium within the same segment. These granules are deposited on the scales of the new epicuticle prior ecdysis, suggesting the presence of calcium on the cuticular surface of both species. Moreover, regions without typical lamellate ultrastructure during postmolt indicate modification of the exocuticle after ecdysis since expansion and hardening must occur after ecdysis. Overall, this work not only added information on cuticular structure of two Neotropical species but also clarified connections between ecomorphology and biological requirements of terrestrial isopods.

Orientador: Otto Bismarck Fazzano Gadig / Banca: Roberto Goitein / Banca: Ulisses Leite Gomes / Resumo: neurocrânio de duas espécies de raias-viola, Rhinobatos percellens e Zapteryx brevirostris. Os exemplares foram coletados na plataforma continental de São Paulo, junto à frota artesanal e industrial. Os indivíduos foram dissecados frescos, com descrição de sete regiões do neurocrânio, e origem, inserção e tamanho relativo dos músculos: epaxialis, quadratomandibularis, preorbitalis, levator palatoquadrati, depressor mandibularis, levator hyomandibularis, depressor hyomandibularis, levator rostri, coracomandibularis, coracohyoideus e coracohyomandibularis. Não foram verificadas diferenças ontogenéticas ou sexual do neurocrânio e musculatura. O apêndice rostral possui diferenças no formato e número de fenestras entre R. percellens e Z. brevirostris. O rostro é mais extenso em R. percellens e existe um par de extensões cartilaginosas no apêndice rostral, semelhantes a barbilhões que não são encontrados em Z. brevirostris. As cápsulas nasais de R. percellens são arqueadas anteriormente. A crista supra-orbital é bem desenvolvida e são observados processos pré e pós-orbitais nas duas espécies. A fontanela posterior é grande e em formato de gota em R. percellens, e em Z. brevirostris ela não é presente em todos os exemplares. Na região latero-posterior da cápsula ótica está a faceta articular da hiomandíbula, que é mais extensa em Z. brevirostris. Na região posterior do crânio está o forâmen magno e em suas laterais estão os côndilos occipitais, mais largos em Z. brevirostris. A musculatura cefálica das duas espécies é semelhante, apresentando diferenças principalmente quanto ao comprimento de tendões, posição de algumas inserções e proporções dos músculos, com exceção do depressor hyomandibularis que possui inserção dividida, ambas na hiomandíbula em Z. brevirostris, e uma na hiomandíbula e outra na primeira cartilagem... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study describes and compares the musculature related to feeding and the neurocranium of two species of guitarfishes, Rhinobatos percellens e Zapteryx brevirostris. The specimens were caught by artisanal and commercial fisheries along the São Paulo continental shelf, southeast Brazil. The specimens were dissected fresh with the description of seven regions of the neurocranium, and origin, insertion and relative size of the muscles: epaxialis, quadratomandibularis, preorbitalis, levator palatoquadrati, depressor mandibularis, levator hyomandibularis, depressor hyomandibularis, levator rostri, coracomandibularis, coracohyoideus, and coracohyomandibularis. No ontogenetic or sexual differences were observed in neurocranium and musculature for both species. The rostral appendix has differences in shape and fenestra number between R. percellens and Z. brevirostris. The rostral cartilage is more extensive in R. percellens in which there is a par of cartilaginous extensions in the rostral appendix, like barbels, not found in Z. brevirostris. The nasal capsules of R. percellens are anteriorly oriented. The supra-orbital crest is well developed and there is pre and post-orbital process in both species. The posterior fontanelle is wide and bead shaped in R. percellens, and is not found in all the specimens of Z. brevirostris. The hyomandibular facet is longer in Z. brevirostris. On the posterior region of the neurocranium there is the foramen magnum, and on each side the occipital condily, that are larger in Z. brevirostris. The cranial musculature of both species is similar, they have differences concerning the size of tendons, position of some insertions and proportion of the muscles, except for depressor hyomandibularis which originates on the superficial hypobranchial raphe and has two insertions, both on hyomandibula in Z. brevirostris, while in R. percellens there is one... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:30:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-02Bitstream added on 2014-06-13T19:18:44Z : No. of bitstreams: 1 santos_cmh_me_rcla.pdf: 2185651 bytes, checksum: c876eb5b088cd7609fb2acb4078a1d09 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / neurocrânio de duas espécies de raias-viola, Rhinobatos percellens e Zapteryx brevirostris. Os exemplares foram coletados na plataforma continental de São Paulo, junto à frota artesanal e industrial. Os indivíduos foram dissecados frescos, com descrição de sete regiões do neurocrânio, e origem, inserção e tamanho relativo dos músculos: epaxialis, quadratomandibularis, preorbitalis, levator palatoquadrati, depressor mandibularis, levator hyomandibularis, depressor hyomandibularis, levator rostri, coracomandibularis, coracohyoideus e coracohyomandibularis. Não foram verificadas diferenças ontogenéticas ou sexual do neurocrânio e musculatura. O apêndice rostral possui diferenças no formato e número de fenestras entre R. percellens e Z. brevirostris. O rostro é mais extenso em R. percellens e existe um par de extensões cartilaginosas no apêndice rostral, semelhantes a barbilhões que não são encontrados em Z. brevirostris. As cápsulas nasais de R. percellens são arqueadas anteriormente. A crista supra-orbital é bem desenvolvida e são observados processos pré e pós-orbitais nas duas espécies. A fontanela posterior é grande e em formato de gota em R. percellens, e em Z. brevirostris ela não é presente em todos os exemplares. Na região latero-posterior da cápsula ótica está a faceta articular da hiomandíbula, que é mais extensa em Z. brevirostris. Na região posterior do crânio está o forâmen magno e em suas laterais estão os côndilos occipitais, mais largos em Z. brevirostris. A musculatura cefálica das duas espécies é semelhante, apresentando diferenças principalmente quanto ao comprimento de tendões, posição de algumas inserções e proporções dos músculos, com exceção do depressor hyomandibularis que possui inserção dividida, ambas na hiomandíbula em Z. brevirostris, e uma na hiomandíbula e outra na primeira cartilagem... / This study describes and compares the musculature related to feeding and the neurocranium of two species of guitarfishes, Rhinobatos percellens e Zapteryx brevirostris. The specimens were caught by artisanal and commercial fisheries along the São Paulo continental shelf, southeast Brazil. The specimens were dissected fresh with the description of seven regions of the neurocranium, and origin, insertion and relative size of the muscles: epaxialis, quadratomandibularis, preorbitalis, levator palatoquadrati, depressor mandibularis, levator hyomandibularis, depressor hyomandibularis, levator rostri, coracomandibularis, coracohyoideus, and coracohyomandibularis. No ontogenetic or sexual differences were observed in neurocranium and musculature for both species. The rostral appendix has differences in shape and fenestra number between R. percellens and Z. brevirostris. The rostral cartilage is more extensive in R. percellens in which there is a par of cartilaginous extensions in the rostral appendix, like barbels, not found in Z. brevirostris. The nasal capsules of R. percellens are anteriorly oriented. The supra-orbital crest is well developed and there is pre and post-orbital process in both species. The posterior fontanelle is wide and bead shaped in R. percellens, and is not found in all the specimens of Z. brevirostris. The hyomandibular facet is longer in Z. brevirostris. On the posterior region of the neurocranium there is the foramen magnum, and on each side the occipital condily, that are larger in Z. brevirostris. The cranial musculature of both species is similar, they have differences concerning the size of tendons, position of some insertions and proportion of the muscles, except for depressor hyomandibularis which originates on the superficial hypobranchial raphe and has two insertions, both on hyomandibula in Z. brevirostris, while in R. percellens there is one... (Complete abstract click electronic access below)

Os isópodos terrestres possuem uma cutícula protetora que mantém a forma corporal, permite locomoção e comunicação com o ambiente e protege contra dessecação, infecção e predação. Assim como nos demais crustáceos, a cutícula é composta por uma matriz orgânica que é mineralizada com cálcio. A cutícula é uma estrutura versátil que reflete adaptações ambientais e a ampla distribuição geográfica do grupo. Dessa forma, a ultraestrutura e a composição da cutícula variam entre espécies. Isópodos terrestres fazem mudas frequentes ao longo da vida para crescer e/ou renovar receptores de superfície, o que resulta em reabsorção e deposição cuticular constante. Esse grupo apresenta muda bifásica e deposição de placas de cálcio nos esternitos anteriores antes da ecdise como estratégia para reciclar o cálcio corporal. Estudos relacionados à cutícula nesse grupo contemplam a ultraestrutura, a composição e a deposição bem como o efeito de alguns fatores ambientais na muda. No entanto, poucos estudos exploram as ligações entre ecomorfologia e história de vida. Essa tese visa explorar diversos aspectos relacionados à cutícula e a muda de duas espécies neotropicais de isópodos terrestres. Atlantoscia floridana e Balloniscus glaber foram usados como modelo uma vez que são frequentemente encontrados nas mesmas localidades e diferem em tipo ecomorfológico e estratégias ambientais. No Capítulo I, foram exploradas as estruturas de superfície e a ultraestrutura da cutícula das duas espécies a fim de ver como as diferenças encontradas podem ser relacionadas à história de vida de cada espécie, utilizando técnicas de microscopia. As espécies diferiram em tipo e disposição das estruturas de superfície bem como em espessura e proporção de camadas da cutícula. De maneira geral, as diferenças das estruturas de superfície estão relacionadas à seleção de microhabitat e nicho ecológico. Características cuticulares ajudam a explicar o hábito endógeno de B. glaber e epígeo de A. floridana enquanto que as diferenças em ultraestrutura são relacionadas a estratégias comportamentais e tolerância ambiental. No Capítulo II, o efeito do cálcio alimentar no ciclo de muda das espécies foi testado. Para isso, dieta experimental e análise estrutural da cutícula foram realizadas a fim de entender como diferentes concentrações de cálcio alimentar interferem na duração do ciclo de muda. Peculiaridades na ecdise em A. floridana refletem morfologia específica do animal. A duração da intramuda foi maior em B. glaber assim como a sobrevivência média nos tratamentos. A duração do ciclo de muda foi influenciada pela concentração de cálcio; uma tendência a menor duração do ciclo com o aumento da concentração de cálcio foi observada em B. glaber, enquanto em A. floridana a diferença encontrada foi apenas entre o controle sem cálcio e os demais tratamentos. Não houve efeito da dieta no grau de mineralização ou na ultraestrutura em B. glaber. Independentemente do tratamento, a maior taxa de mortalidade em laboratório parece estar relacionada com o próprio processo de ecdise, com mortalidade acumulada de 20% do início da ecdise até o início da pós-muda para ambas as espécies. No Capítulo III, a secreção da cutícula durante a pré- e pós-muda muda foi observada utilizando microscopia de transmissão. A deposição seguiu o padrão observado para outros isópodos. Entretanto, grânulos eletrondensos presentes no espaço ecdisial durante a pré-muda são provavelmente constituídos de cálcio, sugerindo a reciclagem de cálcio diretamente da cutícula velha para a nova no mesmo segmento. Esses grânulos são depositados nas escamas na nova epicutícula antes da ecdise, sugerindo a presença de cálcio na superfície cuticular das espécies. Além disso, regiões sem a ultraestrutura típica encontrada na pós-muda indicam que há modificação na exocutícula após a ecdise uma vez que a expansão e endurecimento da nova cutícula apenas após a ecdise. De maneira geral, esse trabalho não apenas trouxe novas informações sobre a estrutura cuticular de duas espécies neotropicias, mas também contribuiu para esclarecer conexões entre ecomorfologia e requerimentos biológicos de isópodos terrestres. / Terrestrial isopods have a protective cuticle that maintains body shape, allows locomotion, enables communication with the environment and protects them against desiccation, infection and predation. As in all crustaceans, their cuticle is composed of an organic matrix that is mineralized with calcium. The cuticle is highly versatile reflecting adaptations to environmental conditions and large geographical distribution of this group. Therefore, cuticle ultrastructure and composition vary among species. Terrestrial isopods molt frequently throughout their lives in order to grow and/or renew surface receptors, resulting in constant cuticular resorption and deposition. In this group, this dynamics of cuticle formation is affected by the biphasic molt and by the calcium deposition on sternal deposits prior ecdysis, strategies to recycle body calcium. Studies related to cuticle on this group include ultrastructure, composition and deposition as well as effect of some environmental factors on molting. However, few studies explore connections of ecomorphology and life history of animals. This thesis aimed to explore various aspects of cuticle structure and molting using two Neotropical species of terrestrial isopods. Atlantoscia floridana and Balloniscus glaber were used as models since they are found in the same locations while differing in ecomorphology and behavioral strategies. In Chapter I, I explored the cuticle surface structures and ultrastructure of both species to see how their differences can be related to each species life history traits, using microscopy techniques. Species differed in surface structures type and disposition, as well as cuticle thickness and layer proportion. Overall, differences in surface structure are related to microhabitat selection and ecological niche. Cuticular features further explain the endogeic habit of B. glaber and epigeic habit of A. floridana, while differences in cuticle ultrastructure relate to behavioral strategies and environmental tolerance. Next, differences on molting cycle and environmental requirements were analyzed. In Chapter II, I tested the effects of dietary calcium on the molting cycle of both species. For that, artificial diet and structural analysis of the cuticle were used to understand how different concentrations of dietary calcium interfere with molt cycle duration. Peculiarities were observed during ecdysis in A. floridana and reflect to specific morphology of the species. Intramolt duration was longer for B. glaber as well as overall survivorship in treatments. Cycle duration was influenced by calcium concentration; a trend of shorter molt cycle length with increasing calcium concentration was observed for B. glaber, while in A. floridana, only difference between control without calcium and other treatments was observed. Degree of mineralization and cuticle ultrastructure of B. glaber showed no difference between treatments. Regardless of treatment or species, higher mortality rate under lab conditions seems to be related to the process of ecdysis itself, with cumulative mortality of 20% from the beginning of ecdysis until the beginning of postmolt. In Chapter III, I used transmission electron microscopy to analyze cuticle secretion in both species during pre- and postmolt stages. Cuticle deposition during premolt followed the same pattern as other terrestrial isopods. Nonetheless, electron dense granules present on the ecdysial space during premolt are likely calcium granules, suggesting the recycling of calcium within the same segment. These granules are deposited on the scales of the new epicuticle prior ecdysis, suggesting the presence of calcium on the cuticular surface of both species. Moreover, regions without typical lamellate ultrastructure during postmolt indicate modification of the exocuticle after ecdysis since expansion and hardening must occur after ecdysis. Overall, this work not only added information on cuticular structure of two Neotropical species but also clarified connections between ecomorphology and biological requirements of terrestrial isopods.