Sea urchins hold clues about a long life

When one sees the spiny, ball-like organism found on the ocean floor, from the poles to the equator, it may not leave them highly impressed. But the nearly thousand species of sea urchins, feeding primarily on kelp and other marine algae, are a delicacy in many coastal cuisines, from Japan to North America. As invertebrates that are genetically closer to humans than to worms and flies, sea urchins have been a model organism for scientists since the 1800s, spilling secrets about life, reproduction and ageing.

Transparent sea urchin eggs have helped humans understand how sperms fertilise eggs to form an embryo. Cyclin, a vital protein necessary for cell division, was discovered when Nobel Laureate Tim Hunt began his research on fertilised sea urchin eggs. Sea urchins have also been sentinels of climate change, helping scientists understand the changes in ocean ecology due to increasing water temperatures and acidification. These ageless marine invertebrates are now helping scientists uncover the secrets to preventing ageing and leading a cancer-free life.

When we age, our cells undergo many changes. Telomeres—cap-like protective structures at the end of our chromosomes—begin to shorten, leaving the threads of life vulnerable to damage. Our cells succumb to oxidative damage and our body loses the capacity to replenish dead cells. Often, the DNA too gets damaged, leading to conditions like cancer. But sea urchins seem to have defied all these processes and do not seem to show signs of ageing. Some species, like the red sea urchins, found in the Northeastern Pacific Ocean live for well over 200 years.

Scientists have discovered that no matter their age, sea urchin telomeres never shorten. They can also regenerate body parts throughout their lives, and their cells are resistant to DNA damage. There has also never been a recorded case of cancer in sea urchins! Understanding the ‘never-die’ attitude of sea urchins holds promise to understanding cancer and other age-related degenerative diseases better, and figuring out ways to prevent them.

— Spoorthy Raman