Behavior of the Hawaiian Spinner Dolphin 'Stenella longirostris' (Schlegel, 1841).

摘要

The Hawaiian spinner dolphin, Stenella longirostris, was recorded from Kure Atoll to the island of Hawaii. It enters atoll lagoons or specific coves or swims over shallow sandy areas, usually near deep water, to rest. Access to nighttime feeding grounds may regulate the location of these rest areas. Rest areas are generally 50 m or less in depth. Natural scars and marks allowed study of movements and school structure. Schools are fluid assemblages of variable size and composition. Only small subgroups within schools may have long term integrity. Spinner dolphin exhibit several aerial patterns, including spinning which is mostly associated with sound production upon reentry, and each is typical of a specific school activity level. Sounds may serve as omndirectional sound sources maintaining school cohesion beyond the limits of vision. The daily cycle of spinner dolphins consists of nighttime feeding, morning approach to shore, morning - midday rest, and travel to feeding grounds near dusk. Feeding is upon scattering layer fishes, squid and shrimp. Dolphins very commonly show scars from large sharks and from the small shark Isistius, which scoops disc-shaped pieces of blubber from them. These wounds heal to form dollar-shaped scars. (Author)