Analysis of the agonistic behaviour and behaviour pattern of Portunus trituberculatus

Abstract

To analyse the agonistic behaviour of Portunus trituberculatus, infrared cameras were used to quantitatively analyse the aggressive behaviour in response to different sex pairings and culture densities and mirror-image stimulation. The results show that: P. trituberculatus has nine behaviour patterns which were correlated, and the fighting process followed a specific, rather than random, process. All nine behaviour patterns were stimulated in response to different sex pairings and culture densities, but only five patterns were induced by mirror-image stimulation. The fighting intensity between the males was significantly higher than that between the females and male and female (p < 0.05). The fight intensity in the 8 crabs/m2 density group was significantly higher than the 4 crabs/m2 and 6 crabs/m2 groups (p < 0.05). The fighting experience had a significant impact on the subsequent fight. The probability of the winner winning again was 83.3%, whereas that of the loser winning again was only 25.0%. In the second round of fighting, the fight intensity of the loser was also significantly lower than those of the winner (p < 0.05). Thus, the fighting process of P. trituberculatus follows a certain regularity, and different sex pairings and culture densities have a significant impact on fighting intensity. Fighting experience also has a significant impact on subsequent agonistic behaviour, with a winner–loser effect.