SCUBA April 2026 issue 164 | Page 52

ENVIRONMENT

Longevity: Litter v Critter

Kerry MacKay offers a startling comparison of the estimated lifetimes of sea creatures and man-made materials found in the ocean

We’ ve all heard that plastic and other rubbish can last a long time in the environment. This month, I thought it would be fun to compare the longevity of some of our rubbish to that of the awesome creatures who live in our seas.

Of course, none of these figures are exact. Lifespans of creatures vary vastly. Likewise, the longevity of different materials depends on the conditions it is exposed to.

Kicking off the competition at speed, many microscopic sea creatures such as Gastrotrichs, live short lives of around 10 days. The shortest living marine fish is the seven-figure pygmy goby, living just 59 days. These creatures’ lifespans are comparable to that of a discarded paper towel or tissue, which lasts around two to four weeks. Or an apple core, which can take around three months to degrade( unless something big eats it).

Zipping away are by-the-wind-sailors( Velella Velella), living only about a year. These outlast cardboard, which comes in

at about three months to degrade, while wooden cutlery is more comparable, taking around six months to a year to break down. Dog poo also lasts around a year. Unless you put it in a poo bag, then it can take over 1,000 years to degrade. So be sure to bin that bag!

Common prawns live for two to five years. Comparable to orange or banana peel, which takes around two years to degrade. Longer than apple cores, because they are made of tougher stuff designed to protect the orange in warmer, more tropical climates than the UK. Reaching to a decade, we have langoustine, aka the delicious scampi. These crustaceans are giving cigarette butts some close competition, lasting around 12 years as litter. They are made of a type of plastic fiber( NOT cotton), and the toxic chemicals they filter from the smoke leach into the environment. Vapes, for comparison, last more than 1,000 years!

Fleece gloves last about as long as a hermit crab, while microplastics and the immortal jellyfish hang around for eons

“ So be sure you don’ t lose that glove overboard!”

Jumping up to 40-50 years, we have hermit crabs, edible crabs, and lobsters. These beat paper cups that last 30 years, and are head-to-head with synthetic fibers, such as our polyester fleeces, nylon, acrylic and elastane. So be sure you don’ t lose that glove overboard!

Doubling our last entry, we’ ve made it to a century. Many turtles live around 80 years, with leatherbacks reaching 100 years. Bowhead whales can live around 200 years. It’ s the humble metal can that is giving these gentle ocean friends some stiff competition, lasting around 100-200 years. Plastic straws also reach the 200- year mark.

Cruising ahead in very slow motion is the Greenland shark, which is the longest-living vertebrate on earth, known to live around 400-500 years. Also, the native ocean quahog( arctic clam) has a record of 507 years old. Here too, are the ubiquitous plastic bottles, plastic bags, and plastic cups, taking around 450-500 years to degrade.

Plastic / synthetic ropes and monofilament fishing line stand alone at around 600 years. Sanitary pads can be anything from 500-800 years, depending on what they were made from. I could not find an ocean creature to match these troublesome litter competitors.

Steadfast at 2,300 and 4,265 years, we have giant barrel sponges and Black coral, respectively. These beauties could beat the familiar vehicle tyre, which takes around 2,000 years to degrade. Finally, topping the charts is the‘ immortal jellyfish’( Turritopsis dohrnii) head-to-head at 1 million years with the glass bottle. Special mention also goes to microplastics. Many litter items never truly disappear. They just slowly disintegrate into such small pieces that we call them microplastics. We do not currently know how long microplastics take to truly disappear, perhaps they are immortal too! �

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