What is an Invertebrate?
April 27, 2020 · Blog
By Blake Scarborough, Educator at Butterfly Pavilion
So you want to get your kids excited about science? There’s a world of opportunity right in your backyard – invertebrates! In this post, we will define what an invertebrate is, provide a few examples, and explain why invertebrates are critical to a healthy planet.
An invertebrate is an animal without a backbone. In fact, invertebrates don’t have any any bones at all! Invertebrates that you may be familiar with include spiders, worms, snails, lobsters, crabs and insects like butterflies. However, humans and other animals with backbones are vertebrates.3 Familiar Groups of Invertebrates
There are over one million invertebrates (1.25 million to be exact) that have been described by scientists (National Geographic 2012). There are three main groups that may be very familiar to you: insects, arachnids and crustaceans.
INSECTS
Insects are the largest group of invertebrates and have six legs, two antennae, and three body parts. Some have wings, but not all. However, if an invertebrate has wings, it is definitely an insect. Some common examples of insects are butterflies, beetles, bees and stick insects.
ARACHNIDS
Arachnids are animals with eight legs, no antennae and two body parts. Two arachnids you are probably most familiar with are spiders and scorpions. Arachnids are often feared, however, they are very beneficial to humans. Arachnids eat pest insects, keep insect populations down and are mostly harmless to humans.
CRUSTACEANS
Crustaceans are animals with 10-14 legs, four antennae and two body parts. Some examples that might come to mind are crabs, lobsters and shrimp. While many crustaceans live underwater, there is one crustacean that is commonly seen outside in the dirt: a pillbug, commonly known as a roly poly. Pillbugs are crustaceans that have adapted to live on land.
Why are Invertebrates Important?
Believe it or not, 97% of all the animals in the world are invertebrates. That means just 3% of the animals in the world are vertebrates (animals like humans, lions, tigers and bears). But not only do invertebrates dominate the world in numbers, but they are the most diverse and important group of animals for a healthy ecosystem.
Invertebrates are a vital food source for many animals. They live towards the bottom of the food chain – a critically important spot to ensure all the other animals further up the chain can survive. For example, crickets are eaten by spiders, then spiders are eaten by birds and then the birds are eaten by bigger predators such as lizards, snakes, foxes and bobcats. If the bottom of the food chain does not provide nutrients to higher up the chain, then the whole system fails.
Invertebrates ensure biological control, keeping an ecosystem in balance. “Biological control” means the control of pests in a natural way – without chemicals. Invertebrates simply eat the pests. Hate mosquitos and flies? Spiders are your friends! Without spiders making a meal of them, insect numbers would rise, creating an imbalance in the ecosystem.
Invertebrates are essential to the creation of products and services that benefit humans. Their “ecosystem services” ensure the production of food, medicines and ensure necessary decomposition of materials in our environment. Without bees, butterflies, beetles and other invertebrate pollinators, many plants would not be able to reproduce and humans would lose access to many essential food sources. Common food products resulting from pollination include vegetables, fruits, seeds, nuts and oils. In fact, it’s estimated that one out of every three bites of food a human takes is the result of a pollinator!
Another important invertebrate to humans is the horseshoe crab. Horseshoe crab blood is use to detect bacterial endotoxins, so they are a vital resource to the medical field. It has been extremely beneficial for cancer patients and others who are extremely vulnerable to medical intervention.
Lastly, many insects are scavengers that feed on dead animals and plants, which recycles nutrients back into the soil, creating a cleaner environment and boosting soil quality. This is critical to ensuring thriving forests and other natural areas.
These are just a few examples of the many ways invertebrates impact our world. Next time you head outside, make sure to thank an invertebrate! If you’re interested in learning more about the incredible diversity of these animals and the many ways they ensure a healthy planet, check out Butterfly Pavilion’s virtual learning opportunities at butterflies.local/virtuallearning.
