9.14: Importance of Arthropods

Are arthropods just creepy and scary?

Many arthropods, such as scorpions, insects, and spiders, have a reputation of being a nuisance or even harmful. But even if they are a little scary to you, that doesn't mean that the world would be fine without them.

Importance of Arthropods

Have you ever been startled by a bee landing on a flower? Or surprised by a swarm of pill bugs when you overturned a rock? These arthropods might seem a little scary to you, but they are actually performing important roles in the environment. Arthropods are important to the ecosystem and to humans in many ways.

Arthropods in Pest Control

Humans use mites to prey on unwanted arthropods on farms or in homes. Other arthropods are used to control weed growth. Populations of whip scorpions added to an environment can limit the populations of cockroaches and crickets. Millipedes also control the harmful growth of destructive fungi and bacteria. When the numbers of millipedes is low, the imbalance between predator and prey can cause harmful microorganisms to flourish, and it can became difficult to manage plagues and diseases through natural processes.

Cockroaches, spiders, mites, ticks and all other insects considered as carnivorous, prey on smaller species to maintain ecological balance. Thus, communities that have a good balance of these arthropods tend to have better pest control.

Ecological Roles

Many arthropods have extremely important roles in ecosystems. Arthropods are of ecological importance because of their sheer numbers and extreme diversity. As mentioned above, bees, wasps, ants, butterflies, moths, flies and beetles are invaluable agents of pollination (see the Figure below). Pollens and grains became accidentally attached to their chests and legs and are transferred to other agricultural crops as these animals move about, either by walking or flying. Most plants actually produce scents to send signals to insects that food (in the form of nectar) is available.

Mites, ticks, centipedes, and millipedes are decomposers, meaning they break down dead plants and animals and turn them into soil nutrients. This is an important role because it supplies the plants with the minerals and nutrients necessary for life. It also keeps dead material from accumulating in the environment. Plants then pass along those minerals and nutrients to the animals that eat the plants.

Figure \(\PageIndex{1}\): Butterfly on buckwheat.

Human Uses

Arthropods are also invaluable to humans, as they are used in many different human-made products. Examples are:

• Bees produce honey and their honeycombs contain beeswax, widely used for making candles, furniture wax and polishes, waxed papers, antiseptics, and fillings for surgical uses.
• The pollens stored in honeycombs were discovered to have a rich mixture of vitamins, enzymes, and amino acids that could provide medical benefits. They were used as ingredients for supplements and medications that could provide relief for colds, asthma, and hay fever.
• Silk produced by arthropods, like those produced by caterpillars to protect their cocoons, is strong enough to use and be woven into fabrics, a discovery first used in ancient China's silk industry.
• The spiders’ web was discovered as an additional material that could provide strength, and has became essential raw materials for Kevlar vests, fishing nets, surgical sutures, and adhesives, as they contained natural antiseptics.

Arthropods as Food

Many species of crustaceans, especially crabs, lobsters, shrimp, prawns, and crayfish, are consumed by humans, and are now farmed on a large commercial scale. Nearly 10,000,000 tons of arthropods as food were produced in 2005. Over 70% by weight of all crustaceans caught for consumption are shrimp and prawns. Over 80% is produced in Asia, with China producing nearly half the world’s total.

Insects and their grubs are at least as nutritious as meat, and are eaten both raw and cooked in many cultures. Beetles, locusts, butterflies, ants, and stinkbugs (which have an apple flavor) are insects that are regularly eaten by people in dozens of countries. In fact, there are more than 1,900 edible insect species on Earth, hundreds of which are already part of the diet of about two billion people worldwide. This is just under one of every three people worldwide, and this number should continue to grow in the future.

The intentional cultivation of arthropods and other small animals for human food, referred to as minilivestock, is now emerging in animal husbandry as an ecologically sound concept. However, the greatest contribution of arthropods to human food supply is by pollination. Three-fourths of the world’s flowering plants and about 35% of the world’s food crops depend on animal pollinators to reproduce and increase crop yields. More than 3,500 species of native bees pollinate crops. Some scientists estimate that one out of every three bites of food we eat exists because of animal pollinators, including birds and bats and arthropods like bees, butterflies and moths, and beetles and other insects.

Summary

• Mites, ticks, centipedes, and millipedes are decomposers, meaning they break down dead plants and animals and turn them into soil nutrients.
• Many crustaceans, especially crabs, lobsters, shrimp, prawns, and crayfish, are food sources for humans.

Explore More

Use the resources below to answer the questions that follow.

Explore More I

• Arthropod Locomotion: Engineering at vimeo.com/37341942 (7:15)

1. Why do scientists study the movement of arthropods?
2. What arthropod characteristic(s) have been integrated into the robot, Ariel?
3. What benefits may we see from robots like Ariel?

Explore More II

• Lobster Mariculture at http://www.marinebio.net/marinescience/06future/lobsterfarm.htm

1. What is one of the biggest obstacles to raising lobsters?
2. How many eggs will a female lobster produce at one time?
3. What is done with the fourth stage juvenile lobsters? Why?

Review

1. Name three examples of an arthropod used as a food source for humans.
2. Describe one important role that arthropods play in the ecosystem.
3. What is one human use of material produced by an arthropod.