Living History: Long-Living Animals

Photo Source: Wikimedia Commons

Humans, all things considered, live relatively long lifespans. At about 73 year life expectancy (according to the UN as of 2019), we tend to outlive many of the animals around us, especially our pets. However, we are certainly do not have the longest life expectancy among animals. In fact, it is utterly fascinating how long some animals have been on this earth.

The reason I became interested in animal life expectancy was through learning about Hanako the scarlet koi fish. In the late 1960s, Dr. Komei Koshihara of Nagoya Women’s College inherited Hanako from his mother’s side (oldest.com). The scientists took a sample of Hanako’s scales (Fish Laboratory). Like trees, koi fish develop rings on their scales as the years pass. After looking at Hanako’s scales under a light microscope, they determined that she was 215 years old (which also implied that she had been born in 1751). After studying the rest of the pond, the researchers found that other koi in the pond also held exceedingly long lifespans, some over 100 years old. The researchers could not pinpoint any specific reason why these Koi lived for so long. They posited that perhaps it was due to the properties of Japan’s clear mountain waters and the love and care Koshihara’s family had shown them all these years. Hanako would pass away in 1977 at 225 years old, making her the longest-living freshwater fish ever recorded.

Cases like Hanako are truly exceptional. At over 225 years old, she surpassed many other animals, even her own koi fish peers. However, compared to some ocean-dwelling animals, even her lifespan seemed relatively short. For example, scientists discovered Ming, an ocean quahog clam off the coast of Iceland (Business Insider). Ocean quahog clams tend to live between 100-200 years, but Ming was estimated to be around 506 years old. Like Hanako, researchers found this out by counting the bands on its shell. Another astounding example of animal longevity is the sponge. Sponges tend to have life expectancies in the thousands of years. One study found a deep-sea sponge (species name Monorhaphis Chuni) that was estimated to be 11,000 years old (National Geographic). Scientists attribute its long life to its stationary lifestyle and the stable deep-sea environment. Deep underwater, there are not as many storms or temperature changes to knock the sponge around, so it is able to live for an very long time (National Geographic).

The animal kingdom never ceases to shock and amaze. We tend to think of their achievements in terms of strength and athleticism, but it is also important to remember some animals’ surprising longevity. Wars have been thought, and whole countries have been created and ended, while animals like the sponge or the ocean quahog clam still survive and thrive. Knowing this can be very humbling. A couple years can go by slowly for us, but for some of these animals, they’re simply a drop in the bucket. If anything, it is a great opportunity to marvel at these mysteries of the natural world.