A false killer whale is a different species from an orca. It is a slimmer, uniformly dark oceanic dolphin that reaches about 16 to 20 feet, while an orca is a black-and-white dolphin that can reach 32 feet. The name comes from the shape of the false killer whale's skull, which resembles an orca's. Its closest relatives are pilot whales, Risso's dolphins, and a few other dolphins, not the orca.
False killer whale vs orca at a glance
| Feature | False killer whale | Orca |
|---|---|---|
| Scientific name | Pseudorca crassidens | Orcinus orca |
| Length | Females up to about 16 ft (4.9 m), males almost 20 ft (6 m) | Males typically 20 to 26 ft (6 to 8 m), largest recorded 32 ft (9.8 m). Females typically 16 to 23 ft |
| Weight | NOAA gives up to about 3,000 lb. Some references list large males near 4,900 lb | Largest recorded male about 10 metric tons (22,000 lb) |
| Color | Uniformly dark gray or black, no white body patches | Black above, white belly, white eye patches, gray saddle patch |
| Build | Slim, with a long tapered head and no beak | Larger and heavier-bodied |
| Dorsal fin | Sickle-shaped and curved | Tall, up to 6 ft (1.8 m) in large males |
| Flippers | Narrow, short, and pointed, with a bulge on the front edge | Large paddles, up to 6.5 ft (2 m) long in big males |
| Diet | Fish and squid, such as mahi-mahi, tuna, and wahoo | Varies by group: fish, seals, sea lions, porpoises, dolphins, whales, sharks |
| Group size | Clusters of 40 to 50 in Hawaii | Pods typically 2 to 15 |
| Lifespan | Oldest estimated 63 years (females) and 58 (males) | Females average about 50 years, males about 30. Maximums at least 90 and 60 |
| Pregnancy | 11 to 16 months | 15 to 18 months |
| Range | Tropical, subtropical, and temperate waters of all ocean basins, mostly offshore | Every ocean |
| IUCN status | Near Threatened. Main Hawaiian Islands population endangered under U.S. law | Data Deficient. Southern Residents endangered |
How can you tell them apart at sea?
- Color. An orca has a crisp black-and-white pattern, including a white patch above each eye and a gray or white saddle behind the fin. A false killer whale is dark all over, without white body patches.
- Dorsal fin. The false killer whale's fin is curved like a sickle. An orca's is tall, and in adult males it can reach 6 feet.
- Head. The false killer whale has an elongated, tapered head with no beak.
- Flippers. Look for the false killer whale's narrow, pointed flipper with a bulge on its leading edge, compared with the large paddles of an orca.
- Size. Even the largest false killer whales are noticeably smaller than adult orcas.
What is a false killer whale?
Pseudorca crassidens is a large oceanic dolphin. Richard Owen described it in 1846 from a fossil skull found in England, and the species was presumed extinct until carcasses washed ashore in Denmark in 1861. The "false killer whale" name comes from the skull's likeness to an orca's (Wikipedia). The Hawaii Division of Aquatic Resources notes that the animals do not resemble orcas at all, because they are smaller and slimmer and lack white patches (DLNR).
False killer whales live in tropical, subtropical, and temperate waters of all ocean basins, and generally prefer offshore water deeper than 3,300 feet, according to NOAA Fisheries. They feed day and night, dive up to 18 minutes, and reach prey at depths of about 984 to 1,640 feet. A review of their diet found 22 species of cephalopods, such as squid and octopus, and 40 species of fish in stomach contents and observations (Baird, 2025). In Hawaii they hunt large fish such as mahi-mahi, ono, and ahi, and they often leap from the water while attacking prey or throw fish into the air.
They are also known for sharing food. NOAA says prey is often shared among animals in a cluster. Researchers have seen them pass a fish back and forth before the catcher takes the first bite, and have documented individuals offering fish to people, including a whale that brought a researcher a yellowfin tuna of about 100 pounds off Kona, Hawaii, in 1984 (Business Insider via Yahoo). NOAA says not to approach, feed, or harass them.
What is an orca?
Orcas are the largest members of the dolphin family, and they live in every ocean. Pods are built around related females and their offspring, and NOAA says pods typically include two to 15 animals. They hunt as a coordinated team, "like a pack of wolves." Resident orcas eat mainly fish, primarily salmon. Transient (Bigg's) orcas eat mainly marine mammals and squid. Offshore orcas eat fish, including sharks (NOAA Fisheries).
For more on orca anatomy and life, see the orca species profile.
Do false killer whales hunt other marine mammals?
Not in any way that has been confirmed. Biologist Robin Baird reviewed the evidence and found no photographic or other documentation of false killer whales eating marine mammals. A widely cited 1980 report of attacks on dolphins near tuna nets, a report of an attack on a humpback calf in Hawaii, and a 1996 report of an aggressive encounter with sperm whales in the Galápagos all lack proof that the whales were killing for food. False killer whales do sometimes harass other cetaceans, but so do many other dolphins. In Hawaii they commonly travel with bottlenose dolphins and other species without showing aggression (Baird, 2025).
Orcas are different. Some orca populations specialize in marine mammals, and orcas off South Africa have killed great white sharks and removed their livers (Scientific American).
How do their social lives compare?
Both species live in long-term family groups. Hawaiian false killer whales live in stable families that hunt daily and share their catch. Females of both species also live well past their breeding years. NOAA lists orcas among the few animals known to undergo menopause, and a 2017 study of false killer whales found that ovulation had stopped in half of females over 45, and every female over 55 had post-reproductive ovaries (Photopoulou and colleagues).
A false killer whale and a bottlenose dolphin in captivity have also produced a hybrid, often called a wholphin. The best-known example is Kekaimalu, a hybrid at Sea Life Park Hawaii (NBC News). For the other parent, see the bottlenose dolphin profile.
What threats do they face?
The most endangered false killer whales live around the main Hawaiian Islands. That population is roughly 140 animals, was listed as endangered under the U.S. Endangered Species Act in November 2012, and continues to decline, according to NOAA and the Hawaii Division of Aquatic Resources. Fishing is the main concern. Whales take bait and fish from longlines and can be hooked or entangled, and the Hawaii agency calls them the species most often caught accidentally in the Hawaii longline fishery. Pollutants that build up in the food chain are the other major threat. NOAA also notes hunting of false killer whales in Indonesia, Japan, and the West Indies. Globally, the IUCN lists the species as Near Threatened.
Orcas vary by population. The IUCN lists the species as Data Deficient, but the Southern Resident population in the Pacific Northwest is endangered, and NOAA's July 2025 census counted 74 whales. All false killer whales and orcas in U.S. waters are protected under the Marine Mammal Protection Act.
Are they dangerous to people?
Orcas rarely threaten people, and no fatal attack has been recorded in the wild (Wikipedia). The NOAA and Hawaii DLNR pages on false killer whales describe no attacks on people. The main conflict is with fishers, since the whales remove fish from lines. If you see false killer whales in the wild, NOAA advises staying at least 50 yards away and limiting viewing to 30 minutes or less. Do not feed, chase, or swim up to them, and check local rules before approaching orcas.
To compare orcas with another look-alike, see pilot whale vs orca.
Sources
- False killer whale species profile (NOAA Fisheries)
- Hawaii's false killer whales (Hawaii Division of Aquatic Resources)
- False killer whales: are they dolphin predators? (Baird, Whalewatcher, 2025)
- Killer whale species profile (NOAA Fisheries)
- Evidence for a postreproductive phase in female false killer whales (Photopoulou et al., 2017)