Bigger Animals Research Articles

Could Humans Use Grasshoppers’ Secrets to Jump Higher?

For humans, the ability to jump is an indicator of physical fitness and the ability to move well. To figure out how to jump higher, one solution is to look at animals that do it very well, like grasshoppers. These animals have a tiny mechanism in their knees that works like a sling and enables them to jump very high. Given how well this sling-like mechanism works, could bigger animals—or humans—use it to make huge jumps? The answer, surprisingly, is no: increasing body size makes animals better at producing energy with sling-like mechanisms, but it also increases the energy required to achieve the same jump height. By reading this article, you will learn how physics and geometry help biologists answer a question about how animals move. Let us jump right in!

Morphology and reproduction of the common opossum (Didelphis marsupialis) dwelling in urban vs rural environments in Antioquia, Colombia

Background: Urban wildlife has been increasing during the last years, however the effect of urbanization on it is poorly understood. The common opossum (Didelphis marsupialis) is very frequent in the Metropolitan Area of Valle del Aburrá (AMVA), in Antioquia, Colombia, where there is also a strong opossum-human conflict that results in a large number of injured/dead opossums. Objective: We evaluated the effects of urban and rural habitats on the morphometry and the reproductive output (litter size in marsupium) of opossums. Methods: A total of 131 opossums were captured, 94 from the AMVA, and 37 from rural areas of Antioquia. Opossums were weighed, measured, sexed, clinically inspected, and photographed. Results: Urban opossums were heavier and larger than rural individuals, regardless of sex, and there were no differences in the reproductive output between the two habitats. Also, urban opossums were more abundant than rural opossums. A potential explanation of these results is that cities favor survival mediated by higher food consumption, but not reproduction. Alternatively, bigger animals could also be explained by an inadequate food consumption rich on carbohydrates which may have potential negative health consequences. We confirmed the sexual size dimorphism of the common opossum in the head and tail lengths but not on the body length. Conclusion: We confirm a significant effect of urban environments on body mass and size of opossums; however, it is unknown whether it is beneficial or detrimental. Litter size is the lowest reported for the species, and there was no difference between rural and urban habitats.

Vascularized versus Free Nerve Grafts: An Experimental Study on Rats.

Vascularized nerve grafts (VNGs) have been proposed as a superior alternative to free nerve grafts (FNGs) for complex nerve defects. A greater regenerative potential has been suggested by clinical and experimental studies, but conclusive evidence is still lacking. In this experimental study, 10 adult male Wistar rats received a non-vascularized orthotopic sciatic nerve graft on their right side, and a vascularized orthotopic sciatic nerve graft nerve on their left side. Functional outcome following nerve regeneration was evaluated through electrodiagnostic studies, target muscles weight and histomorphology, and data of VNGs and FNGs were compared. The results of this study showed a significant difference in the motor unit number of Gastrocnemius Medialis (GM) estimated by MUNE in the VNG side compared to the FNG side. No other significant differences in axonal regeneration and muscle reinnervation were evident at either electrodiagnostic, histomorphology studies or muscle weight. This experimental model showed slight differences in nerve regeneration between VNGs and FNGs, but cannot support a high clinical advantage for VNGs. The results of this study show that VNGs are not strongly superior to FNGs in the rat model, even in avascular beds. Clinical advantages of VNGs are likely to be limited to extensive and thick nerve defects and can only be assessed on experimental model with bigger animals. Also, we showed that the MUNE technique provided a reliable and reproducible evaluation of functional outcomes in the rat sciatic nerve and defined a reproducible protocol for functional evaluation of muscle reinnervation.

The acoustic response of snapping shrimp to synthetic impulsive acoustic stimuli between 50 and 600Hz.

There is growing concern that the noise from human activities in water may impact the detection and production of sound by aquatic animals. Snapping shrimp are sound producing crustaceans and their sound has biological and ecological importance. This paper investigated the effects of pulsed stimuli upon the acoustic behavior of these animals. Changes in snap frequency and duration were assessed before, during and after playbacks and at different levels. Acoustic analysis showed that the duration of the snaps increased significantly during playbacks, whereas the snap peak frequency significantly decreased compared to before and after exposure. Data also showed that when exposed to a sound pressure level equal and above to 130 re 1 μPa (computed particle motion 2.06×10-06 m/s), shrimp responded acoustically. The results suggested that the pulsed acoustic stimuli triggered a behavioral response that included more snapping from bigger animals and movements away from the source.

The role of microplastics in microalgae cells aggregation: A study at the molecular scale using atomic force microscopy

Plastic pollution has become a significant concern in aquatic ecosystems, where photosynthetic microorganisms such as microalgae represent a major point of entry in the food chain. For this reason an important challenge is to better understand the consequences of plastic pollution on microalgae and the mechanisms underlying the interaction between plastic particles and cell's interfaces. In this study, to answer such questions, we developed an interdisciplinary approach to investigate the role of plastic microparticles in the aggregation of a freshwater microalgae species, Chlorella vulgaris. First, the biophysical characterization, using atomic force microscopy, of the synthetic plastic microparticles used showed that they have in fact similar properties than the ones found in the environment, with a rough, irregular and hydrophobic surface, thereby making them a relevant model. Then a combination of optical imaging and separation experiments showed that the presence of plastic particles in microalgae cultures induced the production of exopolysaccharides (EPS) by the cells, responsible for their aggregation. However, cells that were not cultured with plastic particles could also form aggregates when exposed to the particles after culture. To understand this, advanced single-cell force spectroscopy experiments were performed to probe the interactions between cells and plastic microparticles; the results showed that cells could directly interact with plastic particles through hydrophobic interactions. In conclusion, our experimental approach allowed highlighting the two mechanisms by which plastic microparticles trigger cell aggregation; by direct contact or by inducing the production of EPS by the cells. Because these microalgae aggregates containing plastic are then consumed by bigger animals, these results are important to understand the consequences of plastic pollution on a large scale.

Hypothermia as a potential remedy for canine and feline acute spinal cord injury: a review

Severe spinal cord injury (SCI) resulting in permanent sensory-motor and autonomic dysfunction caudal to a damaged spinal cord (SC) segment is a catastrophic event in human as well as in veterinary medicine. The situation of paraplegic/tetraplegic people or animals is further impaired by serious complications and often displays an image of permanent suffering. Therapeutic hypothermia (TH) has shown neuroprotective capacity in numerous experimental and several clinical studies or case reports. Hence, the method draws increasing attention of neuroscientists as well as health care workers. While systemic TH is a too complex procedure for veterinary practice, local application of TH with a reduced risk of the whole body temperature fluctuations and minimal side effects can become one of the therapeutic tools considered in the treatment of acute traumatic SCIs in bigger animals, especially when surgical decompression of spinal medulla and vertebral column reconstruction is indicated. Still, additional large prospective randomized studies are essential for the standardization of therapeutic protocols and the introduction of the method into therapeutic armamentarium in canine and feline spinal traumatology. The research strategy involved a PubMed, MEDLINE (Ovid), EMBASE (Ovid), and ISI Web of Science search from January 2000 to July 2021 using the terms “canine and feline spinal cord injuryˮ, “hypothermiaˮ, and “targeted temperature managementˮ in the English language literature; also references from selected studies were scanned and relevant articles included.

Ontogenetic scaling of pelvic limb muscles, tendons and locomotor economy in the ostrich (Struthio camelus).

In rapidly growing animals there are numerous selective pressures and developmental constraints underpinning the ontogenetic development of muscle-tendon morphology and mechanical properties. Muscle force generating capacity, tendon stiffness, elastic energy storage capacity and efficiency were calculated from muscle and tendon morphological parameters and in vitro tendon mechanical properties obtained from a growth series of ostrich cadavers. Ontogenetic scaling relationships were established using reduced major axis regression analysis. Ostrich pelvic limb muscle mass and cross-sectional area broadly scaled with positive allometry, indicating maintained or relatively greater capacity for maximum isometric force generation in larger animals. The length of distal limb tendons was found to scale with positive allometry in several tendons associated with antigravity support and elastic energy storage during locomotion. Distal limb tendon stiffness scaled with negative allometry with respect to body mass, with tendons being relatively more compliant in larger birds. Tendon material properties also appeared to be size-dependent, suggesting that the relative increased compliance of tendons in larger ostriches is due in part to compensatory distortions in tendon material properties during maturation and development, not simply from ontogenetic changes in tendon geometry. Our results suggest that the previously reported increase in locomotor economy through ontogeny in the ostrich is due to greater potential for elastic energy storage with increasing body size. In fact, the rate of this increase may be somewhat greater than the conservative predictions of previous studies, thus illustrating the biological importance of elastic tendon structures in adult ostriches.

Improvement of Adeno-Associated Virus-Mediated Liver Transduction Efficacy by Regional Administration in Macaca fascicularis.

The liver is a central organ in metabolism and can be affected by numerous inherited metabolic disorders. Recombinant adeno-associated virus (AAV)-based gene therapy represents a promising therapeutic approach for such diseases. AAVs have been demonstrated to be safe, and resulted in high and long-term expression in preclinical and clinical studies. However, there are still some concerns regarding the expression levels that can be achieved and the percentage of hepatocytes that can be transduced. Because of the cell-autonomous nature of most metabolic liver disorders, a high percentage of hepatocytes needs to be corrected in order to achieve a therapeutic effect. The goal of our work was to improve transduction efficacy of the liver by conveying the vector directly to hepatic tissue. Interventional radiology procedures were used to administer an AAV5 vector expressing a secreted form of human embryonic alkaline phosphatase (hSEAP) under the control of a liver-specific promoter to a clinically relevant animal model, Macaca fascicularis. Balloon occlusion of the regional hepatic venous flow was performed while injecting the vector either into the hepatic artery (HA) or, against flow, via the suprahepatic vein (SHV). In both cases the vector was injected into the right hepatic lobules, and the two routes were compared with conventional intravenous administration. Higher hSEAP levels were obtained when the vector was administered via SHV or HA than after intravenous injection. Furthermore, higher expression levels correlated with a higher number of vector genomes in the injected lobules. In conclusion, direct administration of AAV vectors via the hepatic blood flow with simultaneous balloon occlusion of the hepatic outflow increases liver transduction efficacy in comparison with systemic delivery and can be further improved in bigger animals or humans, where it would be technically feasible to inject the vector into the hepatic vasculature in the generality of lobules.

Studying deep diving odontocetes potential prey fields' densities and size structure in Hawaii using a DIDSON imaging sonar

Deep diving odontocetesodontocetes feed in the deep ocean on mesopelagic squid and fish. The distribution of these prey are poorly known but does affect the distribution of deep diving odontocete predators. Hence, it is important to collect data on the density and composition of potential prey to identify deep sea habitats that attract deep diving odontocetes. We used a DIDSON imaging sonar to investigate the density and size structure of mesopelagic animals along the Kona coast of Hawaii, where beaked, sperm and pilot whales are regularly seen. Data were collected at multiple stations during three research cruises by lowering the sonar in the water column to sample at different depths and monitoring the mesopelagic biomass with an EK60 38 kHz echosounder. Foraging activity of whales was monitored at few stations using passive acoustic recorders and a towed array of hydrophones. We were able to count and size 7068 pelagic animals. Density and size varied in space, with higher densities and bigger animals at the offshore stations. The DIDSON was effective at detecting targets bigger than 10 cm, a size range that includes potential prey of deep diving odontocetes. Preliminary data suggest differences may exists in habitat selection by each deep diving odontocetes.

Structure-Activity Relationship of AMP-Luciferin Analogs for In Vivo Imaging

Firefly bioluminescent system is attracting widespread attention as an in vivo imaging tool. Recently, Near-InfraRed (NIR) light (650~1000 nm) is hot topic due to high living body permeability. Although many NIR fluorescence imaging tools are commercialy available, these are not self-luminescent. We study the relationship between structure modification and the firefly luminescence wavelength, that the luciferase of Photinus pyralis (Ppy) was used. And we have succeeded in development of Akalumine® which is a world's first near-infrared light in vivo imaging tool of bioluminescence. Akalumine® is employ in vivo imaging for mice. However, we wish Akalumine® is used much bigger animals like a marmoset, miniature pigs for in vivo imaging. Although Akalumine® is useful for in vivo imaging, it is not enough for big animal. We will give a suggestion for solving this problem. Luminescence of a firefly is two stepwise reactions. Luciferase convert luciferin into AMP-luciferin (intermediate) by adenylation reaction, andthen AMP-luciferin is converted into oxyluciferin by oxygenation reaction. It is known that emission efficiency increase 1000 fold by using the AMP-luciferin, instead of lucifein. So the emission efficiency of luciferin can be raised when AMP-luciferin is used. However, it is very unstable. Then, I will make elaborate AMP-luciferin analogs, and I try to clear practical problem by establishing structure-activity relationship of AMP-luciferin analogs. I will present the details of this result. Figure 1

300. Changing the Route of Administration to Improve Liver Transduction by Recombinant AAV-Based Vectors

The liver is a central organ in metabolism and there are numerous inherited metabolic disorders that have their origin in this organ. Gene therapy represents a promising therapeutic approach for this type of diseases. Although in preclinical studies using AAV-based vectors high and long-term hepatic expression has been achieved, there are still some concerns about the expression levels and the percentage of hepatocytes that can be transduced. This is of particular importance for diseases in which the deficiency of an enzymatic activity is associated with the generation of toxic products that require the transduction of a high percentage of hepatocytes. Therefore, the main goal of our study was to improve liver transduction efficacy by an AAV serotype. For this purpose, the vector was administered directly to the liver via suprahepatic veins (SHV) using a catheter and balloon occlusion or via the hepatic artery (HA) with balloon occlusion of the suprahepatic vein. The experiment was performed in Macaca fascicularis, with 8 animals being infected with a dose of 3×1013 gc/kg of an AAV5 expressing the reporter gene hSEAP (human secreted embryonic alkaline phosphatase) under the control of a liver specific promoter (AAV5-AAT-hSEAP). The first group (2 animal) received the virus systemically in the saphenous vein, the second group (3 animals) received the virus via the SHV with 10 minutes of balloon occlusion and the third group (3 animals) via the HA with 10 minutes of balloon occlusion of the SHV. The procedure could only be performed on the right branch of SHV and HA due to the small size of the left SHV and HA branches, reaching only 40% of the liver. hSEAP-specific activity in serum samples of the groups that received the virus directly in the hepatic blood flow was higher compared to the animals receiving the vector by peripheral intravenous injection. This was correlated with the presence of a higher number of viral genomes in the liver of the animals. Moreover, when their distribution was analyzed we found that the animals that had received the virus through the SHV or HA displayed higher infection rates in the right side of the liver, where the administration had been performed. In conclusion, direct administration of the vector AAV5-AAT-hSEAP through the hepatic blood flow with balloon occlusion was associated with higher transgene expression and an increase in vector genomes in the injected area. Studies in bigger animals in order to reach both sides of the liver should be performed in order to explore the potential use of alternative routes of administration in the clinic.

The relationship between diet and body mass in terrestrial mammals

AbstractDiet and body mass are highly important factors in mammalian ecology, and they have also proven to be powerful paleoecological indicators. Our previous research has proposed a new classification scheme for mammals with more dietary divisions that emphasizes the primary resource in a given diet. We analyzed a database summarizing the dietary preferences of 139 species of marsupial and placental terrestrial mammals (including 14 orders) and their average body masses in order to explore whether this new classification better highlights ecomorphological differences between species. Additionally, the dietary diversity of every species in the data set was quantified by applying the inverse Simpson index to stomach content percentages. We observed a decrease in maximum dietary diversity with increasing body mass. Having lower requirements for energy and nutrients per unit of body weight or ecological advantages such as larger home ranges allows larger mammals to feed on less nutritive feeding resources (i.e., structural plant material). Our results also suggest that body-size ranges are different across dietary specializations. Smaller mammals (<1 kg) are mainly insectivores, granivores, or mixed feeders, while bigger animals (>30 kg) are usually either carnivores or herbivores that feed specifically on grasses and leaves. The medium-size range (1–30 kg) is mostly composed of frugivorous species that inhabit tropical and subtropical rain forests. Thus, the near absence of medium-sized mammals in open environments such as savannas can be linked to the decreasing density of fruit trees needed to support a pure frugivorous diet year-round. In other words, seasonality of precipitation prevents species from specializing on a totally frugivorous diet. Our results suggest that this new classification scheme correlates well with body mass, one of the most studied morphological variables in paleoecology and ecomorphology. Therefore, the classification should serve as a useful basis for future paleoclimatological studies.

Genetic and morphometric variability of the invasive shrimp Macrobrachium rosemberguii in Maranhão State Coast – Brazil

Genetic and morphometric variability of the invasive shrimp Macrobrachium rosemberguii in Maranhão State Coast – Brazil

“Respiratory” turbinates in endotherms and ectotherms

For thirty years respiratory turbinates have been hailed as unequivocal indicators of endothermy in mammals and birds, but their validity as osteologic correlates of metabolic rate is limited to extant mammals. The nasal cavity contributes to heat and water conservation in extant birds, but their trachea also plays an important role. Efficiency of countercurrent heat exchange in the avian trachea increases when cartilaginous conchae are surgically removed. Respiratory turbinates and ectothermy are not mutually exclusive - recent re-examination of the nasal cavity of extant crocodilians reveals presence of a prominent turbinate-like preconcha. Vascularised surface area of the preconcha in the American alligator scales with positive allometry. A larger-than-predicted preconcha provides additional respiratory surface for evaporative cooling in bigger animals, in which cutaneous heat loss is made difficult by the reduced surface area:volume ratio. Thermographic imaging and in vivo measurements of upper respiratory tract temperatures in juvenile alligators provide experimental evidence that the nasal cavity acts as a site of heat dissipation. Heat loss and selective brain cooling, not heat and water conservation, may have been the original selective pressure driving the evolution of respiratory turbinates in archosaurs.

Cell size and cancer: a new solution to Peto's paradox?

Cancer, one of the leading health concerns for humans, is by no means a human-unique malady. Accumulating evidence shows that cancer kills domestic and wild animals at a similar rate to humans and can even pose a conservation threat to certain species. Assuming that each physiologically active and proliferating cell is at risk of malignant transformation, any evolutionary increase in the number of cells (and thus body mass) will lead to a higher cancer frequency, all else being equal. However, available data fail to support the prediction that bigger animals are affected by cancer more than smaller ones. The unexpected lack of correlation between body size (and life span) and cancer risk across taxa was dubbed Peto's paradox. In this perspective, several plausible explanations of Peto's paradox are presented, with the emphasis on a largely underappreciated relation of cell size to both metabolism and cell division rates across species, which we believe are key factors underlying the paradox. We conclude that larger organisms have bigger and slowly dividing cells with lower energy turnover, all significantly reducing the risk of cancer initiation. Solving Peto's paradox will enhance our understanding the evolution of cancer and may provide new implications for cancer prevention and treatment.

The evolution of cancer-related genes in hominoids.

The evolution of cancer suppression is essential for the maintenance of multicellularity. The lack of correlation between body size and cancer risk across species, known as Peto's paradox, suggests that genetic variation in cancer resistance is sufficient to compensate for increases of cell numbers in bigger animals. To assess evolutionary dynamics of cancer-related genes, we analyzed Ka, Ks,and Ka/Ks values in 120 oncogenes and tumor suppressor genes (TSG) among seven hominoid species, including two extinct species, Neanderthal and Denisovan. Ka/Ks of tumor suppressor genes tended to be higher relative to that of oncogenes, consistent with relaxed purifying selection acting on the former. Ka/Ks values were positively correlated with TSG scores, but negatively correlated with oncogene scores, suggesting opposing selection pressures operating on the two groups of cancer-related genes. Additionally, we found 108 species-divergent substitutions that were prevalent germline genotypes in some species but in humans appeared only as somatic cancerous mutations. Better understanding the resistance to cancer may lead to new methods of cancer prevention in humans.

Dental Allometry in Mammals: A Retrospective

Kleiber suggested that mammalian metabolic rate scales with body mass at Mb3/4. Bigger animals use relatively less energy. Gould reasoned that teeth should scale the same way given caloric need. In many cases though, cheek tooth occlusal area increases isometrically, one-to-one with body mass (i.e., Mb2/3). Fortelius reconciled the discrepancy by noting that larger mammals also chew slower, so a given amount of food per bite but few bites per unit time could still mean metabolic scaling of energy consumed in a day. Here I revisit dental allometry, referencing new studies of tooth size, muscle mass, chewing rate, and food fracture scaling. Early predictions have held up reasonably well through the decades, though many more factors involved have emerged. These can be difficult to parse for intepreting deviations from expected tooth size in fossil mammals, including early hominins. Still, relative tooth size variation can help us generate dietary hypotheses.

Concentración de Hg, Pb, Cd, Cr y As en hígado de <i>Carcharhinus limbatus</i> (Carcharhiniformes: Carcharhinidae) capturado en Veracruz, México

Pollution by heavy metals in marine ecosystems in the Gulf of Mexico is one of the hardest conservation issues to solve. Sharks as top predators are bioindicators of the marine ecosystem health, since they tend to bioaccumulate and biomagnify contaminants; they also represent a food source for local consumption. Thus, the objective of this study was to study the possible presence of heavy metals and a metalloid in livers of Carcharhinus limbatus. For this, a total of 19 shark livers were taken from animals captured nearby Tamihua, Veracruz, Mexico from December 2007 to April 2008. 12 out of the 19 captured sharks were males, one was an adult female, three were juvenile males, and three juvenile females. Four heavy metals (Hg, Pb, Cd, and Cr) and one metaloid (As) were analyzed in shark livers using an atomic absorption spectrophotometry with flame and hydride generator. Our results showed that the maximum concentrations found were: Hg = 0.69 mg/kg, Cd = 0.43 mg/kg, As = 27.37 mg/kg, Cr = 0.70 mg/kg. The minimum concentrations found were: As = 14.91 mg/kg, Cr = 0.35 mg/kg. The Pb could not be determined because the samples did not have the spectrophotometer minimum detectable amount (0.1 mg/kg). None of the 19 samples analyzed showed above the permissible limits established by Mexican and American laws. There was a correlation between shark size and Cr and As concentration (Pearson test). The concentration of Cr and As was observed to be higher in bigger animals. There was not a significant difference in heavy metals concentration between juveniles and adults; however, there was a difference between males and females. A higher Cr concentration was found in females when compared to males. None of the samples exceed the maximum limit established by the laws of Mexico and the United States of America. Much longer studies are needed with C. limbatus and other species caught in the region, in order to determine the degree of contaminants exposure in aquatic ecosystems and to identify potential health risks to consumers.

Cardiopulmonary bypass models in rats: problems and perspectives

Cardiopulmonary bypass (CBP) is the premise and guarantee for a successful cardiac surgery. However, its relatively high postoperative mortality and morbidity remains problematic. CPB models in rats have shown remarkable advantages over bigger animals, particularly when applied for research on postoperative cognitive dysfunction. Nevertheless, the high technical requirements limit its wide application. The establishment of an ideal CPB model in rats must mimic the clinical settings and should be highly repetitive.

Cannibalism during intermolt period in early stages of the Southern King Crab Lithodes santolla (Molina 1872): Effect of stage and predator–prey proportions

The anomuran crab Lithodes santolla represents an important fishery resource in the southernmost part of the American continent, where populations are endangered by overexploitation. During first attempts of rearing, intraspecific predation was observed in early stages of L. santolla and may stand as a main source of mortality in cultures. Cannibalism (defined as the sum of injured and dead crabs) between larvae and juveniles of L. santolla was tested in five Predator–prey (P–p) stage combinations and three P–p proportions during the intermolt period. Intra-stage predation in Megalopae (M), crab stage 1 (C1) and crab stage 2 (C2) was similar between stages (~15%) and lower than inter-stage cannibalism. Difference in size of conspecifics was the main cause of cannibalism. Total consumption of prey after 3–5days was observed when 1-year-old crabs (C1yo) encountered either zoeae 1 (Z1), M or C1. Cannibalism in the combination C2–C1 occurred immediately after experiments began. Contrastingly, in the combination C1–M cannibalism started after day 9 of the experiment, suggesting that the swimming ability of M is a key factor for predator avoidance. At the end of intermolt period cannibalism was higher in C2–C1 than in C1–M stage combination and reached 75% and 60% respectively. Directionality of attacks among crabs showed that bigger animals can cause severe damage to smaller ones and not vice versa. Injured predators were only observed in C1–M stage combination and are likely the result of intra-stage cannibalism among C1 when M remain unreachable. P–p proportions had an impact on cannibalism since the more unequal the P–p proportions, the higher the cannibalism in both C1–M and C2–C1 stage combinations. Differential limb loss occurred in L. santolla since walking legs appeared more vulnerable than chelipeds. Although L. santolla showed high predation among conspecifics, cannibalism in early juvenile stages under natural conditions should be lower than in the present study, as density of cultures was high (~950indm−2) and our experimental design provides no refuge/shelter to animals. Hence, the future challenge for massive culturing crabs will be the mitigation of cannibalism.