The mantis shrimp Gonodactylus oerstedii is known to possess eyes capable of colour and polarised light vision. The apposition compound eyes of these creatures are highly mobile and their ommatidia are specialised to analyse the spectral and e-vector qualities of light in a central strip of the eye called the midband. The retina of the midband of Rows 1-4 is tiered with each row being sensitive to a narrow region of the colour spectrum. Row 5 and 6 ommatidia possess many structural features designed to allow the e-vector direction of light to be detected. This thesis investigates the neuroanatomy in the neuropile regions below the retina in an attempt to elucidate the mechanisms which allow colour and polarised light vision to take place. In Chapter 2 the retina-lamina projection of the retinal axons is studied in an ommatidium in Row 3 of the midband, and the findings suggest that the stomatopod is similar to all other crustacea so far studied, despite its unusual retina. Chapter 3 investigates the neuroanatomy of the medulla neuropile regions. A novel region of the medulla externa which deals with colour information is discovered. In Chapter 4 the lamina of Rows 1-4 is looked at in more detail, with the number of monopolar cells and the detailed arrangements of the retinular cell terminals being ascertained. The terminals sensitive to different regions of the spectrum are located in different areas of the lamina cartridge. Chapter 5 looks at many of the issues above but this time in relation to rows 5 and 6 of the midband, which are specialised for polarisation vision. The lamina neuropile is very different to that of Rows 1-4 and again a specialised region of the medulla externa is found which processes information from these rows. This thesis provides evidence that the optic lobes of Gonodactylus oerstedii are comparable to other crustacea but nevertheless may possess some intriguing specialisations related to their extraordinary colour and polarised light vision.

A physical model was built to study the properties of the feeding strike of the mantis shrimp that are responsible for drag reduction and cavitation control. The model had three goals: 1) The model was to be outfitted with a method to collect kinematic, force and cavitation data. 2) The velocity and acceleration profile of the model were to be predicted with a mathematical model of the mechanism. 3) The model was to match as many drag and cavitation sensitive properties of the mantis shrimp strike as feasible and have a means to control the rest. The first iteration of the model met the first goal but not the second or third. It matched the strike in maximum velocity, appendage size and shape and environmental temperature and salinity but did not control acceleration profile, water quality or pressure. Data collected with high-speed video of strikes of the model and Gonodactylus smithii showed the model to cavitate at speeds at which no cavitation was seen in animal strikes. The model was redesigned to be driven by the stored elastic energy in the deflection of a beam spring. The redesigned model reached the animals maximum accelerations but not velocities. Environmental variation was found to not substantially contribute to the variation in cavitation onset velocity between the model and animal experiments.

Orientador: Antonio Leão Castilho / Resumo: Os siriboias são crustáceos pertencentes à ordem Stomatopoda e conhecidos pelo segundo toracópode modificado em garra raptorial, capaz de golpear e quebrar conchas de moluscos, e capturar suas presas. Podem ser separados em dois grupos de acordo com a morfologia das garras: o grupo esmagador, que desfere golpes em sua presa similares a socos de alta potência, e o outro grupo, perfurador, que perfura a presa com as projeções pontiagudas localizadas no dáctilo, último segmento da garra. Existem frequentes relatos anedóticos sobre acidentes em humanos causados por esses crustáceos, mas as informações são imprecisas e muitas vezes o animal não é corretamente identificado pelas vítimas. Este estudo apresenta o relato de 23 pescadores de Ubatuba - São Paulo, que afirmam considerar o siriboia perigoso e que evitam contato direto por conhecerem o risco que o animal oferece, e que os acidentes costumam acontecer com pessoas pouco familiarizadas com o crustáceo. Inclui um relato de lesão causada pelo urópode, informação não documentada anteriormente, e quatro relatos documentados de lesões causadas pelas garras em seres humanos. O estudo resultou ainda em um material informativo sobre os siriboias e prevenção dos acidentes. / Abstract: Siriboias are crustaceans belonging to the order Stomatopoda that are known for the second thoracopods modified to raptorial claws, capable of striking and breaking shells of molluscs and capturing their prey. They can be classified in two groups according to the morphology of the claws: the smasher group, which strikes its prey similar to high-powered punches, and the spearer, which pierces the prey with pointed projections located in the dactyl, last segment of the claw. There are frequent anedoctal reports of human injuries caused by these crustaceans, but the information is inaccurate and often the animal is not correctly identified by the victims. This study presents tertimony of 23 fishermen from Ubatuba - São Paulo, which claim to consider the siriboia as dangerous animals and avoid direct contact, due to know the risk offered. The injuries usually happen in people unfamiliar with the crustacean. It includes one report of an injury caused by the uropod, previously undocumented information, and four documented reports of human injuries caused by the claws. The study proposes informative material about the siriboias and the prevention of injuries. / Mestre

<p> There is a current interest in exploring novel microstructural architectures that take advantage of the response of independent phases. Current guidelines in materials design are not just based on changing the properties of the different phases but also on modifying its base architecture. Hence, the mechanical behavior of composite materials can be adjusted by designing microstructures that alternate stiff and flexible constituents, combined with well-designed architectures. One source of inspiration to achieve these designs is Nature, where biologically mineralized composites can be taken as an example for the design of next-generation structural materials due to their low density, high-strength, and toughness currently unmatched by engineering technologies.</p><p><br></p> <p>The present work focuses on the modeling of biologically inspired composites, where the source of inspiration is the dactyl club of the Stomatopod. Particularly, we built computational models for different regions of the dactyl club, namely: periodic and impact regions. Thus, this research aimed to analyze the effect of microstructure present in the impact and periodic regions in the impact resistance associated with the materials present in the appendage of stomatopods. The main contributions of this work are twofold. First, we built a model that helped to study wave propagation in the periodic region. This helped to identify possible bandgaps and their influence on the wave propagation through the material. Later on, we extended what we learned from this material to study the bandgap tuning in bioinspired composites. Second, we helped to unveil new microstructural features in the impact region of the dactyl club. Specifically, the sinusoidally helicoidal composite and bicontinuous particulate layer. For these, structural features we developed finite element models to understand their mechanical behavior.</p><p><br></p> <p>The results in this work help to elucidate some new microstructures and present some guidelines in the design of architectured materials. By combining the current synthesis and advanced manufacturing methods with design elements from these biological structures we can realize potential blueprints for a new generation of advanced materials with a broad range of applications. Some of the possible applications include impact- and vibration-resistant coatings for buildings, body armors, aircraft, and automobiles, as well as in abrasion- and impact-resistant wind turbines.</p><br>