Of all fish, none is known for its harrowing life cycle more than the sockeye salmon, whose scientific name is oncorhynchus nerka. They go by several other names, including the blueback salmon, red salmon and the kokanee salmon.

These fish are members of the salmonidae family, which also includes trout, graylings, char, freshwater waterfish and the biggest member of the group: the now-extinct saber-toothed salmon, which grew over 9 feet long. Imagine trying to reel that in!

Sockeye salmon, on the other hand, measure two to just under 3 feet long and weigh 5 to 15 pounds.

Why do these fish have so many names? To answer that question, we have to dig into their life cycle. Where these fish live and what they look like varies depending on the time of year and how old the fish are. For most of their lives, these fish live off the Pacific Coast, as far north as Alaska and as far south as California. Other populations can be found off the coast of Japan and Siberia.

At one stage of their lives, sockeye are silver-blue and are called blueback salmon. Unlike most members of their family, blueback primarily feed on tiny ocean-going animals called zooplankton.

Bluebacks don’t remain bluebacks forever. These fish didn’t originally live in the ocean; they hatched in rivers far inland, and this is where they want to go to lay their eggs. The fish gather in a large group called a shoal and begin swimming upriver to the place of their birth.

Their physical appearance changes drastically as they journey inland. Their bodies become bright red; their heads turn green. Males develop a long, toothy snout that they use to compete aggressively against other males for breeding rights.

This is where another name comes into play: red sockeye. They are called red salmon for obvious reasons, but why “sockeye”? Sockeye is an English version of a word that speakers of the Halkomelem language use to refer to this fish: suk-kegh, which simply means “red fish.”

The salmon encounter obstacles along every stretch of their journey. Sharks — including the appropriately named salmon shark — the humboldt squid, lampreys, seals, sea lions, dolphins, porpoises, orcas and humpback whales consume great quantities of salmon before they even reach the shore.

As they swim upriver, they must travel against the current and negotiate through small waterfalls. Inland, black and brown bears, eagles, gulls and other predators know when the fish are traveling upstream and wait patiently along their migration route. Once they arrive at their spawning grounds, the males compete to fertilize eggs laid by the females.

This leaves another name: the kokanee salmon. These salmon belong to fully freshwater populations: They do not migrate to and from the ocean. Nevertheless, these salmon also return to the place of their birth to spawn.

For the duration of their journey, the salmon do not eat. This takes its toll on the fish, and upon giving rise to the next generation, they die. But they do not die in vain. The nutrients within their bodies are released back into the water and the surrounding ecosystem, benefitting not only their offspring but all animals living in and around salmon spawning areas.

When the young salmon hatch, six or nine weeks later, they are called “fry.” The fry are minnow-like and vulnerable to predators, not the least of which being other, larger species of salmon.

This is why they stay in the relative safety of the body of water where they hatched. Their diet consists of insects and other invertebrates until, one to three years later, they grow large enough to head out to sea and continue the circle of life for these enigmatic fish.

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