In this article, we look at some amazing diving beetle adaptations that help them to survive their lives on both land and water.
Beetles are the largest number of insects found on earth (forming around 1/3rd of all insects) and are, by far, the oldest.
Over the years, they have developed some interesting adaptions that allow them to survive in various conditions, from the hot deserts to the still waters of lakes.
The diving beetle is one such type of beetle that can live on both land and water while preying on smaller insects and larvae.
Unlike amphibians, the diving beetle can only breathe atmospheric air, which it carries along with itself underwater.
It also comes in various colors, such as olive, yellow, black, and leathery brown. Let’s learn more about these small yet fascinating creatures.
What is a Diving Beetle?
Diving beetles are a type of fresh water-dwelling insects that thrive in the waters of North America, Europe, and Asia.
They are commonly found in slow-moving waters, mostly with lots of vegetation.
Despite being aquatic, they do have wings and mostly fly at night to new waterbodies.
Their navigation relies on reflected moonlight to identify waterbodies – hence they often grass into glass facades.
Like all beetles, they have strong, crushing jaws.
They feed on aquatic life, such as invertebrates, small tadpoles, and other fish and dead insects.
Using their jaws, they incapacitate the prey, tear them into pieces, and finally suck out their juices.
Adaptations of the Diving Beetle
Among the entire beetle family, only 4% are aquatic beetles.
This means that over time, the diving beetle has evolved a number of adaptations that allow them to live and thrive in aquatic environments.
Here are some things that are different:
Breathing Under Water
Diving beetles are often referred to as nature’s “scuba divers.” Their bodies are adapted to breathing air.
Before entering the water, they create bubbles underneath their wings (elytra), which they breathe in through their spiracles.
The elytra have two rows of punctures for breathing, which helps distinguish this species from others, such as the water scavenger beetles (which have only 1 row of punctures).
They also have a siphon-like structure which they elongate out of their body and above the water to breathe oxygen from the air.
Wings & Flight
These aquatic insects belong to the order Coleoptera, meaning insects with “sheath-wings.”
This refers to the strong and leathery front wings these insects have called the elytra. These hard wings help protect their softer hindwings in water.
Only adults develop flight wings and can thrive on both land and water.
Eggs are laid on the land (under leaves), and larvae grow up in the water without wings. They pupate near the shore, and finally, adults with wings emerge.
Adult beetles can fly long distances in search of new water bodies. Males have wings with shiny surfaces, whereas female wings have grooves running along them.
While swimming underwater, they will surface, holding only their abdomen upto the water’s surface to collect more air under their wings for another dive.
Eyes
Being great predators, they rely on their superb vision and crushing jaw system. Larvae have simple lens eyes called stemmata, with six on each side of their head.
Adults have a total of 14 compound eyes, with each eye having two overlaid retinas. Despite all these eyes, all beetles simply have a dark and light-based vision comprising tiny dots.
Paddle Like Legs
To adapt to swimming in the water, adult diving beetles’ back legs are paddle-shaped.
These legs are more suited for wading through water than walking on land – giving them an awkward gait on solid ground.
Along with the paddles, their entire body is smooth and streamlined to allow for the least water friction while propelling themselves ahead.
Males also have an adhesive section on their forelegs, which they attach to the back legs of the female beetle during mating.
Cleaning Their Surroundings
Diving beetles are great aquarium pets as they help keep them clean.
With a good balance of algae, beetles, and plants, one can even set up a self-cleaning ecosystem in a garden pond.
Overall, they are considered to be top predators in many freshwater ecosystems and play an important role in controlling the population of other organisms.
Because of this, they are a preferred addition to fisheries, where they feast on the smaller fish, which are considered pests, and also get rid of mosquito larvae that can grow in stagnant water. The diving beetle larvae are an even voracious predator.
Frequently Asked Questions
How long can a diving beetle stay underwater?
While there’s not been any specific research on this question, there are a few sources that mention that diving beetles can stay underwater for as long as 36 hours.
It won’t be surprising, considering all the adaptations that they have evolved in order to stay in the water.
This includes the ability to “breathe” underwater, paddle-like feet, and a streamlined body.
They have even evolved special eyesight to tackle underwater viewing.
In fact, as larvae, they live entirely underwater and only come out once they become adults.
What is the Behaviour of the great diving beetle?
Diving beetles are one of the few species of beetles in the world that can live inside water for long periods of time.
They do so by a special adaptation – they can carry oxygen under their wings when they dive.
In their early years, these beetles are voracious eaters and known for being ferocious regarding the hunt – so much so that they are called “water tigers”.
They can take on and eat much larger organisms than themselves.
When they grow into adults, diving beetles do not lose out on their appetite – they eat everything from small pests to tadpoles to frogs and more.
What are the adaptations of the great diving beetle?
Some of the key adaptations that help adult great diving beetles include:
Ability to breathe underwater by capturing air under their wings.
Paddle-like feet to help move in the water.
Compound eyes with a specialized vision that lets them see things clearly when in the water
Cleaning up their surroundings by eating up all the pests and bugs in their water sources.
The ability to fly when on land
How do diving beetles move?
Diving beetles have tiny paddle-like features on their feet, which they use to propel themselves forward in the water.
This is one of the unique adaptations that has helped them live both on land and for a long time in the water.
Their body is also much more streamlined than other insects. This helps them move along smoothly when in water.
When they are on land, they can both walk and fly. They fly with the help of their hind wings.
Wrap Up
Diving beetles are a great companion addition to garden ponds—hatcheries and freshwater habitats alike.
They do inject a toxin into their prey; however, it is not enough for humans or even smaller pets like cats to show any symptoms.
They’re a very safe pet for aquariums, especially if your kid is interested in studying the life cycle and adaptions of insects.
Thank you for reading!
Reader Emails
Diving beetles are one of the most fascinating creatures on the planet, and their unique adaptations that we explained above would surely have given you some idea why.
A lot of our readers have been interested in these adaptations and how these beetles are able to do what no other of their kind can.
Please go through emails from some of our readers enquiring about these unique creatures, and the engaging discussions that we have had about them.
Letter 1 – Giant Black Water Beetle, not Diving Beetle
Location: Sacramento CA
April 1, 2012 4:44 pm
Hi Mr. Bugman,
I love your site and have for years. Can you tell me what this 1-3/4” beetle is? My husband is holding him. We found him in the garden in March here in Sacramento Ca.
Signature: Fellow Bug Lover
Dear Fellow Bug Lover,
This is an aquatic beetle, and judging by its size, we are relatively confident it is a Diving Beetle in the family Dytiscidae which is well represented on BugGuide. Though they are aquatic, Diving Beetles fly quite well.
Correction: April 6, 2012
Thanks to a comment from MichaelH, we are linking to the correct species on BugGuide. The Giant Black Water Beetle is also known as the Giant Water Scavenger.
Letter 2 – What ate the Diving Beetle???
Geographic location of the bug: North Dakota…
Date: 09/10/2017
Time: 10:47 PM EDT
Could you help us identify this couldn’t be found anywhere on internet.
How you want your letter signed: Rhonda Delzer
Dear Rhonda,
You have discovered the remains of a Predaceous Diving Beetle in the family Dytiscidae, possibly a Harris’s Diving Beetle, Dytiscus harrisii, which we found pictured on BugGuide. A bird or other predator has eaten the soft, nutritious abdomen and left the harder, less edible parts like the head, thorax and elytra for you to find.
Letter 3 – Boreal Diving Beetle
Geographic location of the bug: Curtis, Washington
Date: 12/03/2017
Time: 10:41 PM EDT
This beetle/bug landed on our porch tonight just at dusk. I took a couple of photos and it flew off, straight up for at least 50 feet. It is about 1.5 inches long. Does anyone know what type of beetle it is? I live in Western Washington State and this photo was taken today, Dec.3rd
How you want your letter signed: Sparty
Dear Sparty,
After you went through the trouble to create a composite view of this Predaceous Diving Beetle, we cropped it back into two distinct images. We believe your individual, because of your location and the grooved elytra or wing covers, that this is a Boreal Diving Beetle, Dytiscus alaskanus. According to BugGuide, its range is: “Transcontinental in Canada and Alaska, also present in parts of n. US as far south as Colorado” and “Overwinter as adults in permanent waters.”
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