Both killer whale species belong to the dolphin family, live in social groups and are top predators at the end of the food chain.
Pseudorca crassidens is a bit smaller than the orca and, like orcas, hunts mainly in groups, although one such group also catches and eats other predators of the sea, e.g. sharks.
The dominance of the large marine hunters at the end of the food chain is countered by a growing burden of environmental toxins that are "up the food chain" and eventually reach the killer whales, such as polychlorinated biphenyls (PCBs) and mercury.
These toxins have severe health effects on the animals.
The increasing overfishing of the oceans by humans is also making it increasingly difficult for the killer whales to find sufficient food.
Globicephalus grayi Burmeister, 1867
Orca crassidens Gray, 1846
Orca destructor Cope, 1866
Orca meridionalis Flower, 1865
Phocaena crassidens Owen, 1846
Pseudorca crassidens meridionalis Deraniyagala, 1945
Pseudorca grayi Burmeister, 1872
Pseudorca mediterranea Giglioli, 1882
Pseudorca meridionalis Gray, 1866