Optimization of environmental variables in habitat suitability modeling for mantis shrimp Oratosquilla oratoria in the Haizhou Bay and adjacent waters

Habitat suitability index(HSI)models have been widely used to analyze the relationship between species abundance and environmental factors,and ultimately inform management of marine species.The response of species abundance to each environmental variable is different and habitat requirements may change over life history stages and seasons.Therefore,it is necessary to determine the optimal combination of environmental variables in HSI modelling.In this study,generalized additive models(GAMs)were used to determine which environmental variables to be included in the HSI models.Significant variables were retained and weighted in the HSI model according to their relative contribution(%)to the total deviation explained by the boosted regression tree(BRT).The HSI models were applied to evaluate the habitat suitability of mantis shrimp Oratosquilla oratoria in the Haizhou Bay and adjacent areas in 2011 and 2013–2017.Ontogenetic and seasonal variations in HSI models of mantis shrimp were also examined.Among the four models(non-optimized model,BRT informed HSI model,GAM informed HSI model,and both BRT and GAM informed HSI model),both BRT and GAM informed HSI model showed the best performance.Four environmental variables(bottom temperature,depth,distance offshore and sediment type)were selected in the HSI models for four groups(spring-juvenile,spring-adult,falljuvenile and fall-adult)of mantis shrimp.The distribution of habitat suitability showed similar patterns between juveniles and adults,but obvious seasonal variations were observed.This study suggests that the process of optimizing environmental variables in HSI models improves the performance of HSI models,and this optimization strategy could be extended to other marine organisms to enhance the understanding of the habitat suitability of target species.

Contrasting on Hydrocarbon Generation Modeland Characteristics of Pyrolysis of Modern Aquatic Plant(Gloeocapsa) vs MarineAnimal(Mantis Shrimp)

A hydrocarbon model of the modern aquatic plant Gloeocapsa and the aquatic animal mantis shrimp was found in thermal simulating experiment. The results show that the modern aquatic plant Gloeocapsa is characterized by late generation, late termination and a long duration of oil generation, while the aquatic animal mantis shrimp is characterized by early generation, early termination and a short duration of oil generation. The nalkanes from Gloeocapsa and mantis shrimp are characterized by peak carbon C 15 -C 17 . With increasing thermal simulating temperature, the peak carbon changes from C 17 to C 15 , and the odd-even predominance of nalkanes becomes less clear. The products from Gloeocapsa contain abundant phenanthrene and naphthalene compounds, and even a little retene, while those from mantis shrimp are dominated by naphthalene compounds, and are poor in phenanthrene compounds. Gloeocapsa and mantis shrimp are rich in C 27 sterane, relatively rich in tricyclic terpanes (C 19 -C 29 ) and hopanes (C 27 -C 35 ), poor in 5α,14β,17β sterane, and coprostane does not disappear until 450 ℃. The tricyclic terpanes in Gloeocapsa are characterized by peak carbon C 23 and C 23 >C 21 , and in mantis shrimp by C 21 and C 21 >C 23 . The content of pregnanes is very low at low temperature of thermal simulation, while above 360 ℃, high levels of pregnane series compounds and even degraded C 25 and C 26 steranes occur in thermal simulation products.

Long-term and monthly changes in abundance,size composition and spatial distribution of the mantis shrimp Oratosquilla oratoriainthe BohaiSea

With the decline in fish resources worldwide,the ecological dominance and economic importance of crustaceans have obviously increased.Among crustacean species,mantis shrimps are increasingly dominant in many coastal waters of the world.In China,Oratosquilla oratoria is the most widely distributed and productive species of mantis shrimp,and its relative resource density is the highest in the Bohai Sea.In this study,we analysed the long-term and monthly population characteristics of O.oratoria in the Bohai Sea,including its relative resource density,body size and spatial distribution.The results showed that the relative resource density of O.oratoria in the Bohai Sea increased from 3.59 kg/h in 1982 to 14.48 kg/h in 2018,and the percentage of this species that serves as a fishery resource increased from 4.22%in 1982 to 35.27%in 2018,based on the mean relative resource density in May and August.The relative resource density of O.oratoria in the fishing moratorium season from May to August was significantly higher than that in the other months of fishing season,and the relative resource density decreased rapidly after the fishing moratorium ended.The relative resource density of O.oratoria was the highest in summer(August),followed by in autumn(October)and spring(May),and it was the lowest in winter(January).The relative resource density of O.oratoria in the western Bohai Sea was higher than that in the eastern Bohai Sea.The mean body weight of O.oratoria in the Bohai Sea decreased from 21.95 g in 1982 to 14.34 g in 2018,based on the mean body weight in May and August.The body size of O.oratoria in the fishing moratorium season was significantly higher than that in the fishing season,and the body size decreased rapidly after the fishing moratorium ended.Overall,in the context of declining resources of most fishery species,the relative resource density of O.oratoria increased due to its hardiness and adaptability,and its body size decreased under intensive fishing over the past 30 years.The fishing moratorium system had a great influence on the population dynamics of O.oratoria in terms of the relative resource density and body size in the Bohai Sea.

Mantis Shrimp-Inspired Underwater Striking Device Generates Cavitation

Different from direct impact damage exerted by limbs of most organisms,mantis shrimps’appendages can carry out ultra-fast,powerful underwater strikes with cavitation superimposed damage to harvest hard-shelled prey.The power amplification systems and cavitation generation of mantis shrimp have attracted vast attention of researchers.Much effort has been paid to developing mantis shrimp-inspired striking robots;however,none of them are capable of generating cavitation during impacting hard objects yet.In this paper,an underwater striking robot named Shrimpbot was developed to reproduce the cavitation phenomenon when striking hard objects.Shrimpbot incorporates a Latch-Mediated Spring Actuation(LaMSA)to slowly store energy and release it instantaneously.A Diamond-Shaped Four-bar Linkage(DSFL)stretches springs to more effectively store elastic energy by reducing the maximum torque requirement of the motor.This design promised an average power amplification of over 30 times of the motor.Shape optimization and hydrophobic coating on the hammerhead and hand of Shrimpbot helped to reduce the water drag.The accomplished Shrimpbot reached an impact speed of over 12 m/s,at an acceleration of 2×10^(3) m/s^(2),an impact force of more than 1200 N in water,very close to the performance of mantis shrimp.More importantly,cavitation bubbles accompanied with the impacts were observed for the first time in mantis shrimp-inspired robots.Shrimpbot ingeniously employs only one motor to accomplish the striking automatically and repeatedly for practical purposes.Shrimpbot mimics the cavitation generation skills of mantis shrimp,which could facilitate the understanding of its mechanical principles and fluid dynamics of ultra-fast power-amplified systems of mantis shrimp and even those energy storage mechanisms of jumping robots or exoskeleton robots.

A Hybrid Territorial Aquatic Bionic Soft Robot with Controllable Transition Capability

In this paper,a bionic mantis shrimp amphibious soft robot based on a dielectric elastomer is proposed to realize highly adaptive underwater multimodal motion.Under the action of an independent actuator,it is not only able to complete forward/backwards motion on land but also has the ability of cyclically controllable transition motion from land to water surface,from water surface to water bottom and from water bottom to land.The fastest speed of the soft robot on land is 170 mm/s,and it can crawl while carrying up to 4.6 times its own weight.The maximum speeds on the water surface and the water bottom are 30 mm/s and 14.4 mm/s,respectively.Furthermore,the soft robot can climb from the water bottom with a 9°slope transition to land.Compared with other similar soft robots,this soft robot has outstanding advantages,such as agile speed,large load-carrying capacity,strong body flexibility,multiple motion modes and strong underwater adaptability.Finally,nonlinear motion models of land crawling and water swimming are proposed to improve the environmental adaptability under multiple modalities,and the correctness of the theoretical model is verified by experiments.