Quantitative Research On Population Motor Behavior Features Of Sea Cucumber Apostichopus Japonicus(selenka)

Animals can benefit from aggregation behavior,which could directly affect growth and reproduction of animals.There are great economic and ecological value in aquaculture of sea cucumber Apostichopus japonicus.Research on aggregation of sea cucumber could help figure out animal tracking,protection and sustainable multiplication.Based on video recording and software analysis,we studied animal motor behavior and aggregation,effects of food resources,habitats and predators on different features of sea cucumber group.The main results and contents are as follows:1.Effects of intraspecific members and food resources on motor behavior of sea cucumberWe describe movement of sea cucumber A.japonicus in laboratory conditions using time-lapse video and behavior analysis software with reference to wild density.Experiments reveal that intraspecific members significantly affect movement behavior of A.japonicas.Animals moved more randomly when provided food in the absence of intraspecific members,which could ensure that animals can spent more time feeding.Individuals moved more directly in the presence of others to escape from arena(P<0.05).Food can eliminate intra-specific competition,as single individual in groups move more randomly when provided with food.There are no significant difference between mouth and body velocity in all treatment(P>0.05).These results indicate that intraspecific competition affects movement of A.japonicus,which may potentially determine exploitation of animals,but food resources can eliminate intraspecific competition,and thus may be important causal agents in the wild distribution of A.japonicas.2.Effects of habitat distribution and intraspecific competition on aggregation features of sea cucumberAnimals can obtain ecological benefit while aggregating in groups.Sea cucumber A.japonicus showed high preference for habitat with adequate food resources in the field.However,there was little research explicating how habitats and intraspecific members affected the aggregation of A.japonicus.We investigated the aggregation behavior of A.japonicus based on time-lapse video camera in the Lab.The results showed that:sea cucumbers showed strong preference for the habitat rather than the wall of the tank with animals spending more time at habitat(P<0.05);the sea cucumbers distributed in 2 or3 habitats separately versus animals aggregated in 1 habitat(P<0.05);as the density reached to 15 individuals every tank(11.31 ind/m~2,d=1.3m),the mean attractive rate and mean attractive time significantly decreased(P<0.05)which indicated that there was intraspecific competition among animals.In conclusion,aggregation of sea cucumbers is significantly affected by intraspecific competition and habitat,and sea cucumbers distributed in different patches.Sea cucumbers would escape from the central area to reduce the competition when the density was high.This study identified the effect of habitat distribution and intraspecific competition on the aggregation of sea cucumbers in the Lab and provided a theoretical reference for the cultivation and sustainable use of resources of sea cucumber in the wild.3.Effects of predator on aggregation behavior of sea cucumberThere are few studies focusing on predation on sea cucumber.It had been found that predator starfish Asterias amurensis had strong predation selectivity on sea cucumber.In this research,we studied the aggregation size and aggregation characteristics of sea cucumber under the pressure of predator A.amurensis.It was found that the average aggregation size,mean crowding and index of patchiness of sea cucumber group were not significantly different from single individual.The average aggregation size,mean crowding and index of patchiness of sea cucumber group at density 3 and 5 showed no significant difference under the pressure of predation of sea star(P>0.05),which indicated that aggregation of sea cucumber was not significantly affected by predators.In summary,the population size of sea cucumber was not changed under the pressure of predator.The sea cucumber had formed no aggregation defense mechanism against predator.