Killer whales, also called orcas, are the largest species in the dolphin family (1). They are also one of the strongest predators in the marine environment, which is where their name came from (1). Killer whales are found in every ocean in the world and live in both coastal waters and open seas (2). 

Orcas are apex predators in their food chain (1). They use echolocation to hunt and travel around (1). Although their diet may consist of penguins, fish, squid, birds, seals, squid, and even adult whales, they are very picky eaters; once they have found what their family likes, they are rarely known to switch diets (1, 3). Killer whale hunting groups work just like wolf packs; they work cooperatively to effectively catch prey (1). 

Killer whales sleep differently then humans do. Unlike humans, orcas cannot breathe while they are subconscious like humans can (3). Therefore, to get their sleep, they must stay conscious to remember to breathe (3). To solve this problem, orcas perform unihemispheric sleep (3). This is when they only let one side of their brain sleep at a time (3). While one side of their brain sleeps, they keep the opposite eye . This way, they can fully rest both sides of their brain while always remaining conscious (3). 

Today, many orcas are being held captive in parks as entertainment (1). However, many studies have proven that they are definitely not meant to be held in captivity (1). Orcas are meant to swim 40 miles and dive 100 to 500 feet a day (1). They are also meant to stay in tight family groups (1). However, in captivity, they do not have much space to swim in and are forced into artificial groups, which is proven to make them feel stressed (1). 

1: https://www.nationalgeographic.com/animals/mammals/o/orca/

2: https://www.fisheries.noaa.gov/species/killer-whale

3: https://uk.whales.org/whales-dolphins/facts-about-orcas/