Climate change can wreak havoc on oceans. With waters getting warmer and more acidic, populations of fish and other marine life have fallen drastically. But one group of animals is thriving despite the odds. The populations of cephalopods—a class of animals that includes cuttlefish, squid, and octopus—have actually increased in number in recent years.
To determine this trend, scientists studied 35 different cephalopod species living in the world’s oceans. They tracked down octopus and cuttlefish species that like to hover on the ocean floor. Other species they spied on were types of squid that travel great distances to breed and find food. Despite their different behaviors, all cephalopod populations have grown steadily over the past 60 years.
Cephalopods can be tricky to study because they are hard to find and count. So researchers looked at data collected by national fisheries and scientific surveys conducted over the years. They used this data to calculate how many cephalopods fishers caught over a given time period—known as the catch rate—which allowed them to estimate the size of the populations.
One reason for the population boom is that these creatures can adapt quickly to changes in the environment. “Cephalopods are often called ‘weeds of the sea’,” says researcher Zoe Doubleday, who led the study. They have short lifespans of one to two years, breed quickly, and produce a lot of eggs. These factors have helped cephalopods survive in a changing environment. Many of their competitors and predators, which tend to live longer and grow more slowly, have declined in number—another factor that’s helping to maintain cephalopod numbers.
The Humboldt squid, also known as the jumbo flying squid, is one example of just how adaptable cephalopods can be. The squid live in warm waters off the coast of Mexico, Chile, and Peru. When waters in the region became unusually cold due to the weather phenomenon La Niña in 1999 to 2000, the squid grew to nearly 10 times their normal size. These mega-squid weighed between 55 to 88 pounds!