December 1, 2022

The False Killer Whale: it’s not even a whale, but very real, and very interesting

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The word killer has a very negative connotation, and it’s not hard to understand why. But deep in the underwater world, not everything that’s called “killer” is that scary — at least to us. While the killer whale is one of the smartest and most fearsome predators in the seas, the false killer whale is a different story.

Don’t worry — it’s a false killer whale. Image credits: William Warby.

Killer whale vs false killer whale

The false killer whale (Pseudorca crassidens) is a large marine mammal belonging to the dolphin family (delphinids); it’s a mammal just like other dolphins. Technically, it is not a whale and is most closely related to Risso’s dolphins and pilot whales, rather than killer whales as their name suggests.

It is named so (even its Latin name means “fake killer whale”) because the shape of their skulls is similar to that of killer whales. But if you’re not a trained biologist and you don’t have access to its skull, here’s how to identify the killer whale. 

A “true” killer whale. Image via Wiki Commons.

Killer whales (or orcas) generally have black bodies and white undersides with a white patch above and behind the eye.  Meanwhile, false killer whales have dark gray bodies except for their ventral side (underside) that is much lighter in color.

Size comparison will reveal a significant difference as orcas are the largest member of the dolphin family and can grow to nearly ten meters (33 feet) in length and weigh 10,000 kilograms (22,000 pounds) whereas the false killer whale only reaches six meters (20 feet) and 1,500 kilograms (3,000 pounds). Another defining characteristic of a false killer whale is its narrow pointed head and prominent bulbous forehead. They also have distinct s-shaped flippers and small dorsal fins. For the most part, though, it’s easiest to look for differences in color — the orcas will have distinctive white spots, whereas false killer whales don’t.

Excellent social skills 

These animals are found globally in all tropical and subtropical oceans as well as deep offshore waters. Aside from the same skull structure, orcas and false killer whales have quite similar behavior. Historically, the name “killer whale” was given by ancient sailors after they observed them to prey upon whales. Similarly, false killer whales feed on large fish species like mahi-mahi tuna, predatory fish like sailfish and a variety of fish and squid. As top predators, it’s innate to them. 

Though quite intimidating, these dolphins are gregarious and form strong social bonds. Small subgroups to larger aggregations of false killer whales have been observed and this strategy is mainly for easier prey hunting. They are also very friendly to other species like bottlenose dolphins in New Zealand, with whom they formed long-term associations. These social links can get so close that fake killer whales and other species of dolphins can stay in the same pod. Some research suggests that these partnerships help them better detect potential threats that could loom around.

In fact, they sometimes even perform sexual (both heterosexual and homosexual) interactions with these dolphins — though they have also been documented to kill and eat dolphins. Normally, they feed on squids and fish, though these dolphins have been even documented to hunt some sharks.

Mixed-species pod of common bottlenose dolphins (Tursiops truncatus) and false killer whales. Image credits: Luke Halpin.

Family is something not taken for granted in their species as females who no longer produce calves still continue to play a role in family groups, mostly by looking after the young of other females. They only produce offspring once every 6-7 years and the mum will continue to nurse her baby for up to two years. It is a tedious task that requires commitment and being a mom is just ingrained in their system. The whales continue to live for quite a long time after their menopause, which generally occurs at some 45-55 years of age. It’s thought that their society is formed around mothers and grandmothers.

The false killer is one of three toothed-whale groups and it can echolocate, using something called a “melon organ” on its forehead. It uses echolocation both for navigation and for finding prey. The melon organ is larger in males, which suggests that males may be better at echolocation.

We’re still learning a lot about this creature. For instance, only recently did scientists learn that this species consumes pelagic octopus and that the species can also steal fish from fishing lines.

“Understanding their food habits is foundational to their biology and ecology and has relevance to fishery interactions (an identified threat to the population) and in defining critical habitat for this endangered species,” said Kristi West, lab director and an associate researcher at UH Mānoa’s Hawaiʻi Institute of Marine Biology, and author of a recent study about false killer whales.

Threats to the species 

Image via Wiki Commons.

To date, there is little known documentation of the natural predators of this species. They seem to be at the top of their food chain (or very close to it) in their ecosystem. Their biggest threat comes from humans who often view them as nuisance or competitors. Since they are active swimmers, they often approach fishing vessels and steal target fish from longlines as observed in Japan, Hawaii, the Indian Ocean, and the Gulf of Mexico. Due to this, they are often killed. 

Underwater noise pollution caused by human activities has also negatively impacted the species, making them disoriented and prone to entanglement in fishing gears. Additionally, there is the threat of plastic pollution which has detrimental effects on their health and reproductive success. There is a serious concern about its population around the main Hawaiian islands which was only estimated to be around 150 to 200 individuals in 2012 — a steep decline from their number in 1989. As such, the Hawaiian population has been put under the Endangered category under the US Endangered Species Act. 

Though different from the orcas in various characteristics, false killer whales are experiencing the same threats that the orcas and all other marine wildlife faces. Threats brought by anthropogenic activities like pollution or climate change are not new and they affect every creature on land and in the ocean — and the false killer whale is no exception. Most often, however, it’s fishing lines and fishermen that threaten it.

Because they spend so much time offshore, it’s hard to study them and there’s still much we’ve yet to learn about them. The species is considered Near Threatened, but many aspects regarding its population remain unclear. Ultimately, if we want to protect this species (and other ones as well) we must keep the oceans and the atmosphere as clean as possible.