Distinctive behaviour of Thai pygmy squid, Idiosepius thailandicus Chotiyaputta, Okutani & Chaitiamrong, 1991
1997
Jaruwat Nabhitabhata (Department of Fisheries, Bangkok (Thailand). National Institute of Coastal Aquaculture. Rayong Coastal Aquaculture Station)
Thai pygmy squid Idiosepius thailandicus displayed distinctive behaviour when observed in the laboratory. The squids adhered to horizontal and vertical substrata by their dorsal adhesive organ. The sex of pygmy squids could be recognised from the posture of adhering, prey seizure, colour pattern, and the larger size of females. Males preferred the larger females, but no pair formation was observed in mating. Using both tentacles, the mating male fixed spermatophores to the buccal region of the female in a head-to-head position without grasping her arms. Based on differences in hovering and adhering positions of each sex, four patterns of mating behaviour could be distinguished. The female needed 5-10 seconds to lay and attach an egg capsule to the substratum. On average each female laid 160 egg capsules. Egg capsules contained a single embryo, 1.8 mm in diameter, and incubation lasted 10-13 days. The planktonic hatchlings had a mantle length of 1 mm.
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