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Why counting octopus “rings” is so important

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Maria Gill
Maria Gill
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Land octopuses have been around for a while At least 330 million years ago. While they evolved before dinosaurs roamed the planet, their current descendants don't live very long. They generally die shortly after mating or laying eggs, with some species of octopus surviving Only six months The average lifespan is about two to three years. Some types like Giant Pacific octopus It can live up to five years at most.

To maintain sustainable fish populations, fisheries must ensure a sufficient number of breeding individuals Left alone or released again To the wilderness. Government agencies can enforce Fishing laws, while scientists can formulate laws by understanding the reproductive lives of different fish. For octopuses, their short lifespan was evolutionarily acceptable. However, as human taste for these cephalopods grew, meeting demand became a problem.

In an effort to protect the longevity of this ancient and incredibly intelligent sea creature while ensuring that octopus fisheries remain sustainable, a team of scientists in Australia has created the first known step-by-step guide to determining the age of an octopus. The evidence is detailed in A Paper published April 11 in Journal of Marine and Freshwater Research It provides a first step in establishing guidelines for fishermen to follow and ensure they catch octopuses that are not of reproductive age.

year Perima octopus Hatching, one of the species used to help develop the guide. Credit: Erica Durante.

There are several ways to know the age of an organism, a process called senescence. Trees are known to have rings that indicate how many years they have lived. to examine Teeth and bone structure In mammals too it can reveal similar information about age. This process was a bit difficult for octopuses. In the new paperThe team looked at them Nibs and pens– Internal shells located near their gills. They identified growth rings similar to tree rings found here and are a useful tool for verifying the age of the octopus.

[Related: Octopuses rewrite their own RNA to survive freezing temperatures.]

“Over the past 30 years, various studies have explored different methods for octopus aging, but only a small number of researchers worldwide have the practical knowledge to implement these methods in the laboratory,” said study co-author and Maritime University of South Australia. Environmental scientist Zoe Doubleday He said in a statement. “It is important that we do not lose this practical scientific knowledge because by determining their ages, we can understand the impact of different catch rates on populations.”

The team explains how scientists can examine Octopus beak, stipules, and growth rings In the laboratory to determine the age of the animal. In the future, these methods could be applied in the wild to determine the age of octopuses living in the ocean.

A mother southern octopus and her clutch of eggs
Mother southern octopus with a clutch of eggs. Credit: Erica Durante.

“Understanding the lifespan of octopuses helps maintain sustainable fisheries,” said Erica Durante, study co-author and PhD student at the University of South Australia. He said in a statement. “If you know the age of any species, you can estimate how quickly it will grow and reproduce and how hard you will struggle to keep the fishery sustainable.”

[Related: Eating seafood can be more sustainable and healthy than red meat.]

Age data can also tell scientists how long it takes an animal to mature. In this way, octopuses that are not mature enough to reproduce can be avoided when hunting. According to DuranteAge is important for the general conservation and management of the species, whether commercially fished or not.

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One tricky part is that while growth rings on trees represent years,… The growth rings on an octopus represent days. According to the team, these methods should be customized for each of these methods Nearly 300 species of octopus are known. The team also acknowledges that these guidelines will continue to evolve as we learn more about the lives of these multi-legged creatures.

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