Are Insects Animals?
The long, spindly appendages and bulging eyes of a praying mantis looks about as far from a human as you can imagine. Despite their alien appearance, insects are animals, just like you and me.
Insects share the kingdom Animalia with all animals on earth. However, the impression that insects are so very different from us is well founded. Insects diverged from mammals and other animals long ago. Scientists estimate that the last common ancestor of humans and insects lived over 500 million years ago.
What is phylogeny?
In a basic sense, phylogeny defines what is what. What is an animal? What is a plant? Where do we draw the lines? These decisions can be extremely complicated. Taxonomy is our best representation of the history of life on earth.
All living organisms on earth share a common ancestor. Phylogeny is the study of this history. Understanding the relationships between species allows us to better understand evolution and life itself.
All life on earth is categorized according to its evolutionary history. We have organized the evolutionary tree of life into a taxonomy. This defines the categories used to describe groups and subgroups. These groupings are based on appearance, behavior, distribution, and genetics.
The most commonly used groupings are domain, kingdom, phylum, class, order, family, genus and species. All animals are in the animal kingdom, Animalia. Plantae is the kingdom of plants. Fungi occupy their own kingdom as well.
Depending on who you ask there are one or two more kingdoms, containing bacteria, protozoa and other single-celled organisms. These species are so different, they occupy a different domain, prokaryota. The disagreements that exist over these classifications show just how complex this evolutionary history is!
What are Arthropods?
Insects are in the kingdom Animalia. After this, they diverge from humans. The next rank is phylum. Insects are Arthropods (meaning jointed foot), in the phylum Arthropoda. This phylum also includes millipedes, scorpions, spiders and crabs.
All arthropods have jointed legs, segmented bodies and an exoskeleton. Arthropods are extremely diverse. They inhabit all environments on earth. They make up 84% of all known animal species. Insects make up the majority of these species.
Entomologists believe that the majority of arthropods are still undiscovered! Estimates go as high as 10 million undescribed species. There is still a lot that we can learn from insects.
Humans, on the other hand, are vertebrates. Vertebrates exist in the phylum Chordata, along with fish, birds, worms and much more.
So what is an insect?
Insects are species in the class Insecta. All animals in this class share common traits. They have a body divided into three sections (the head, thorax, and abdomen.) They also have a pair of antennae and most have wings.
This distinguishes them from the other arthropods. These generally have more legs, 2 body segments, and never have wings.
What makes insects unique?
Insects are unique from arthropods in some interesting ways. The sheer diversity and number of insects leads to some very unique adaptations.
Their life cycles are far more complex than most animals. Many start as larvae that must undergo metamorphosis to reach adulthood. This unusual process is another reason people think of insects as so different from ourselves.
Insects also have some very unusual eating habits. Species including bees in Thailand and moths in the Brazilian Amazon will feed on the tears of humans and other animals! They feed on the protein and salt they contain.
There are also many insects that feed on blood. Though mosquitoes are an obvious example, the vampire moth is another blood-sucking insect that feed on humans!
Another wild example of insect adaptation comes from the already strange stick bug. This insect is often eaten by birds who are lucky enough to see through the bugs camouflage.
Though this may sound like the end of the line for the poor bug, it can be a blessing in disguise. The eggs of this insect can survive the birds digestive tract. Therefore, the next generation of stick bugs can travel huge distances that no bug could ever walk.
More wild adaptations of insects are being discovered all the time. Unfortunately, we may not have much time left to discover their secrets.
Insects are not safe from the effects of humans
The abundance and diversity of insects may make them seem invincible. Unfortunately, humans have managed to make a significant dent in their populations over the last few decades. Insects are disappearing at a far greater rate than other animals.
There has been a massive decrease in flying insects during the summertime. One study in Germany measured an 82 percent drop in insects over the last 27 years.
Research indicates that the earth is entering a mass extinction. This extinction is being fueled by human effects on the environment.
This rapid extinction of insects risks losing species before they have even been identified. In addition, the loss of insects would be detrimental to all life on earth.
Insects provide essential pollination services to many plants. Some of the largest food sources for humans require insect pollination. Entire ecosystems are at risk of collapse without insects.
Though it is not entirely clear why insect populations are plummeting, there are many ways in which humans are contributing.
The use of pesticides on crops has detrimental effects for many insect species. Bees are an essential pollinator, however, neonicotinoid pesticides are causing them to die off. These compounds contribute to colony collapse disorder (CCD). CCD has been seen around the world and has led to disastrous decreases in bee populations.
Plastic pollution is a huge environmental impact of humans. It has recently been shown that up to half of freshwater insects have eaten microplastics. These plastics accumulate in the ecosystem as predators eat insects that have consumed plastics.
Insects are an important, intriguing and extremely diverse group of animals. Though they may look creepy or strange, they are vital to a functioning ecosystem.