Marine Life Encyclopedia
Marine Mammals
Risso’s Dolphin
Grampus Griseus
Distribution
Worldwide in tropical to sub-polar latitudes
ECOSYSTEM/HABITAT
Coastal to open ocean (pelagic)
FEEDING HABITS
Active predator
TAXONOMY
Suborder Odontoceti (toothed whales), Family Delphinidae (dolphins)
Risso’s dolphins feed primarily on squid of all sizes (including the humboldt squid) and are therefore excellent divers, spending much of their feeding time at depth, hunting for their preferred prey. Scientists believe that much of the white scarring on the heads of these animals may be a result of aggressive interactions with large-bodied squids. Risso’s dolphins feed mostly at night, a probable result of the migration of their preferred prey to shallower waters in the dark. Scarring is also a likely result of interactions among adult males and between males and females.
This species, like all mammals, reproduces via internal fertilization and gives birth to live young, which nurse from their mothers for at least several months.
Though Risso’s dolphins are offered some or complete legal protection throughout much of their range, they are still hunted for food and for fertilizer in some places and are captured accidentally in fisheries targeting other species throughout most of their range. Current population trends are not known, but scientists believe the Risso’s dolphin to be common and to be a species of least concern. Further study of this species and monitoring of its populations is required to determine whether or not they are stable.
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