Orcinus orca
Identification.
Unmistakable black-and-white marking; the largest member of the dolphin family.
Galápagos context.
Transient pods have been documented, with sightings clustering in the Bolivar Channel between Isabela and Fernandina. A widely-documented 2016 incident recorded an orca tossing a sea turtle into the air, described by the guide who filmed it as extremely rare even by orca standards.
Encounter context.
Visitor sightings are explicitly infrequent. Documented prey in Galapagos waters includes sea lions, dolphins, fish, and, very rarely, green sea turtles.
Seasonality.
No reliable season identified; sightings are opportunistic.