My Science School

As their name suggests, giant anteaters are large. Like so many large mammals the world over, these creatures too are facing rising extinction risk, especially in Brazil. What are the reasons for this? Come, let's find out.

Giant anteaters are native to Central and South America. In 2020, the Pantanal region of South America witnessed fires that destroyed about a third of the area. It proved to be injurious or fatal for wildlife such as jaguars inhabiting the region. According to a report, the fires killed "an estimated 17 million animals". The numbers are not available for those injured or displaced. But among those that suffered are giant anteaters. Apparently, "more than 50 giant anteaters injured or displaced by the Pantanal fires were taken in by state rescue projects - a leap from 13 the previous year". In 2021, Pantanal witnessed fires again, though on a scale smaller than the previous year. However, reports suggest that a few areas from 2020 suffered in 2021 too - this could spell disaster for the species there since they'd be denied time for recovery. Several animals are also indirectly affected by such fires. For instance, young animals could be orphaned and ones trying to escape such fires could get involved in accidents or end up in the hands of poachers. As for giant anteaters, some tried to escape the fire in 2021 and got hit by cars; they were rescued.

But, fires are not the only reason for falling giant anteater populations. A report says "Brazil's anteater populations have fallen 30% over 26 years". As solitary creatures, they require a large range for habitation. But this is becoming more and more difficult due to land seizures, expansion of farming, ranching, and mining "in the Amazon and the Brazilian savanna". Further, the animal also has "a low population growth rate due to its life history of long gestation periods and single offspring".

The giant anteater plays a significant role as both predator and prey. While it is consumed by jaguars and pumas, the mammal consumes large quantities of insects, especially ants and termites. Given this interconnectedness, the extinction of this insectivore can have unimaginable impacts on its ecological range.

Fires are not the only reason for falling giant anteater populations. As solitary creatures, they require a large range for habitation. But this is becoming more and more difficult due to land seizures, expansion of farming, ranching, and mining "in the Amazon and the Brazilian savanna". Further, the animal also has "a low population growth rate due to its life history of long gestation periods and single offspring".

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Often, conservation stories underline the importance of the role of all creatures-big and small-for balance in ecosystem. For instance, krill crustaceans barely two inches long are a huge link in the global food chain. If such a small organism can have a telling impact on the food chain, one can only imagine the kind of effect larger animals have in an ecosystem. So, when the population of a large animal plunges, it is always a cause for concern.

Grey whales are among the largest animals on Earth- nearly 50 feet long and weighing over 40 tonnes. These giants are known for their long annual migration of more than 15,000 km "between feeding grounds in the Arctic and breeding grounds in Baja Mexico" Recent research has revealed that the number of these fascinating creatures is witnessing a worrying slump- by nearly 40% in just six years. From 27,000 whales in 2016, the number stands at a concerning 16,650 today. Several factors are attributed to this decrease. One of them is the increase in strandings in 2019, when about 600 of these creatures washed up dead along the west coast of North America Though boat collisions and killer whale attacks caused a few of these deaths most of the dead whales were malnourished which takes us to n crucial of interconnectedness in an ecosystem. It is believed that the malnourishment could be the result of "the whales’ food sources of tiny crustaceans and other invertebrates they prey on in the Arctic shifting due to environmental changes. Further, the overall population among West Coast grey whales "coincides with diminished reproduction" While there were 383 baby whales during the calf production season last year, there have been a mere 217 newborns this year - "the lowest number since such counts began in 1994"

Grey whales were close to extinction several decades ago due to commercial whaling before their population improved due to timely conservation efforts. Even then, the 80s and 90s saw a plunge of about 40%, and eventually they rebounded. It is important for this whale population to recover too because they keep the population of certain other creatures in the food chain in check. Even in death-as carcasses- these large marine mammals help feed several other organisms.

Often, grey whales are washed up dead along the U.S. west coasts. Though boat collisions and killer whale attacks cause some deaths, researchers say malnourishment is a major reason. With tiny crustaceans and other invertebrates shifting due to environmental changes, the grey whales are left without food.

Picture Credit : Google 

There's proof we are increasingly losing species, and this is not good for us humans

What is mass extinction?

To be classified as a mass extinction, at least 75 % of all the species on Earth must go extinct within a short geological period of less than 2.8 million years. That timeframe seems long to us because modern humans have only existed for about 2,00,000 years so far.

Mass extinction is not new

Extinctions and speciations (species evolving over time) do not happen at uniform rates through time; instead, they tend to occur in large pulses interspersed by long periods of relative stability. These extinction pulses are what scientists refer to as mass extinction events. The Cambrian explosion was a burst of speciation some 540 million years ago. Since then, at least five mass extinction events have been identified in the fossil record (and probably scores of smaller ones). Arguably the most infamous of these was when a giant asteroid smashed into Earth about 66 million years ago in what is now the Gulf of Mexico. The collision vapourised species immediately within the blast zone. Species were killed off later by resultant climate change and volcanic activity too.

Are humans responsible for the current crisis?

Humans have been implicated in smaller extinction events going back to the late Pleistocene (around 50,000 years ago) to the early Holocene (around 12.000 years ago) when most of the megafauna, such as woolly mammoths, giant sloths. diprotodons, and cave bears, disappeared from nearly every continent over a few thousand years. Much later, the expansion of European colonists throughout the world from about the 14th Century precipitated an extinction cascade first on islands, and then to areas of continental mainland as the drive to exploit natural resources accelerated. Over the last 500 hundred years, there have been more than 700 documented extinctions of vertebrates and 600 plant species. These extinctions come nowhere near the 75 % threshold to include the modern era among the previous mass-extinction events. But those are just the extinctions humans have recorded. In fact. many species go extinct before they are even discovered- perhaps as many as 25 % of total extinctions are never noticed by humans. But it's not the total number of extinctions we should focus on; rather, it's the extinction rate. Even the most conservative estimates place the modern era well within the expected range to qualify as a mass extinction. If the current rate of extinction continues we could lose most species by 2200.

When species disappear

One may think that so long as the species that provide resources for modern societies survive, there's no reason to consider extinction a problem. The evidence suggests otherwise. Species loss also erodes the services biodiversity provides us. These include reduced carbon removal from atmosphere (which climate change), reduced pollination and increased soil degradation that compromise our food production, poorer water and air quality, more frequent and intense flooding and fires, and poorer human health. Even human diseases such as HIV/ AIDS, Ebola, and COVID-19 are the result of our collective indifference to the integrity of natural ecosystems.

There's still hope

We could potentially limit the damage if societies around the globe embraced certain fundamental, yet achievable, changes. We could abolish the goal of continuous economic growth, and force companies to restore the environment. We could limit undue corporate influence on political decision-making. Educating and empowering women would also help stem environmental destruction.

Did you know?

• In the timeline of fossil evidence going right back to the first inkling of any life on Earth- over 3.5 billion years ago - almost 99 % of all species that have ever existed are now extinct. That means that as species evolve over time, they replace other species that go extinct.
• When the giant asteroid hit our planet, about 76 % of all species around at the time went extinct, of which the disappearance of the dinosaurs is most well-known. But dinosaurs didn't disappear altogether-the survivors just evolved into birds.

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Alaska's snow crabs are named so for their love of cold water, which they inhabit. But, due to the heatwaves in 2018 and 2019, their habitats were not cold enough, and this is suspected to be the "key culprit in the mass die-off. The warmer are believed to have affected the species in more ways than one.

Recently, the Alaska Department of Fish and Game announced that the Bering Sea snow crab season will stay closed for catching during 2022-23 to conserve and rebuild the species. (Though they are found in a couple of other places too, it is in Bering Sea that these crabs are abundant and also grow to reach "fishable sizes".) The announcement follows an annual survey by the National Oceanic and Atmospheric Administration, which discovered that the crustacean numbers "fell to about 1.9 billion in 2022, down from 11.7 billion in 2018", a reduction of nearly 85%. What caused this dramatic loss, and how will closing the season help the species? Come, let's find out.

Alaska's snow crabs are named so for their love of cold water, which they inhabit. But, due to the heatwaves in 2018 and 2019, their habitats were not cold enough, and this is suspected to be the "key culprit' in the mass die-off. The warmer temperatures are believed to have affected the species in more ways than one. For instance, studies "have pointed toward a higher prevalence of Bitter Crab Disease as the temperature heats up". Further, unlike in cold waters, these crabs "need more energy to stay alive" in warmer waters, causing them "metabolic stress", which likely led to limited movement, and eventual starvation. Apart from this, young crabs require low temperatures of water where their mobility is high, helping them evade predation. When the waters warm, they slow down, and their chances of being targeted by their major predator- the Pacific cod - are higher. 5

However, it is interesting to note that a marine biologist has said that the current predicament was linked more to climate change rather than to overfishing because fishing "removes only large adult males" but the decline in population appears across all sizes of snow crabs. If that's the case, what explains closing the area for catching these crabs?

Because, the temperature of the water has now returned to normal; closing will help the reproduce and recover. Comfortingly, "this years survey saw significant increases in the immature crabs compared to last year".

Picture Credit : Google