Backswimmer vs Water Boatman: A Deep Dive into Aquatic Insects

Backswimmers and water boatmen are two fascinating aquatic insects that are often confused due to their similar appearance and habitat.

They belong to the order Hemiptera, commonly known as “True Bugs”, and can be found in various freshwater habitats such as ponds and lakes.

While both insects are boat-shaped and less than 1/2″ long, they come from different families and exhibit distinct behavioral and physical characteristics.

The backswimmer is known for its unique swimming style – it spends its life rowing around belly-up, with a dark belly and a light back.

In contrast, water boatmen are typically a bit smaller than backswimmers and swim along the bottom of the pond with their head down.

They possess different mouthparts and diets; water boatmen lack the standard piercing beak and instead ingest living material like diatoms, while backswimmers are predatory and use their beaks to catch and feed on other small aquatic insects or arthropods.

Backswimmer vs Water Boatman

Appearance and Identification

Backswimmers and water boatmen are aquatic true bugs that can often be confused due to their similar appearance.

Here are some visual differences to help identify them:

Backswimmer (Notonecta glauca): Characterized by its dark belly and light back, backswimmers have an oval shape and swim with their ventral side (belly) facing upwards ¹.

Water Boatman (Family Corixidae): Smaller than backswimmers, these bugs have slender, oval bodies, and red-eyed appearance.

Their hind legs are scoop or oar-shaped, and they swim head-down along the pond bottom searching for food ².

Differences in Habitat

Both backswimmers and water boatmen reside in freshwater habitats; however, they inhabit different areas within these environments:

• Backswimmers: They are usually found swimming freely on the water surface as they prefer open water habitats.
• Water Boatmen: They tend to dwell near the pond or lake bottom, where they can scavenge for food sources.

Feeding Habits

Here are the differences in feeding habits between backswimmers and water boatmen:

• Backswimmers: These insects are primarily carnivorous, preying on small aquatic insects, larvae, and even small fish. They use their sharp mouthparts to pierce and kill their prey.
• Water Boatmen: They feed on living materials, such as diatoms, algae, and detritus³. Lacking the standard piercing beak of other aquatic true bugs, water boatmen instead ingest their food sources.

Comparison Table:

Classification and Family Relations

Family Notonectidae

The family Notonectidae, commonly known as backswimmers, belongs to the order Hemiptera.

These invertebrate creatures are identified as true bugs and are known for their unique swimming style.

They swim upside down and are characterized by their aggressive piercer-predator behavior.

Some features of Notonectidae:

• Prey on invertebrates and small vertebrates
• Use their piercing mouthparts to suck out bodily fluids
• Compete with small fish for food, but can also be prey for larger fish

Family Corixidae

On the other hand, water boatmen, belonging to the family Corixidae, also fall under the Hemiptera order.

Despite sharing the same order, water boatmen are quite different from backswimmers.

They are not predators, instead, they feed on algae and other organic materials in the water.

Some characteristics of Corixidae:

• Primarily herbivores
• Known for their rowing movement through the water
• Less aggressive than backswimmers

A comparison table of Notonectidae and Corixidae:

Physical Adaptations

Front Legs and Hind Legs

Backswimmers and water boatmen utilize different legs for varied purposes. For instance:

• Backswimmers: their front legs are for capturing prey, while their long, oar-like, hair-covered hind legs are for efficient swimming.
• Water boatmen: their front legs are adapted for crawling on submerged surfaces, whereas the flattened third pair of legs help in underwater rowing motion.

Covered Hair Troughs for Storing Air

Both backswimmers and water boatmen possess covered hair troughs that enable them to store air for breathing underwater.

These troughs are crucial for their survival.

Swimming Mechanisms

Backswimmers and water boatmen have distinct ways of swimming:

• Backswimmers: swim upside down, with their specially adapted oar-like hind legs propelling them.
• Water boatmen: use their flattened third pair of legs as paddles, allowing them to row through water with ease.

Diet and Feeding Habits

Backswimmer Prey

Backswimmers are piercer-predators that are known to feed on a variety of prey, including:

• Tiny fish fry
• Tadpoles
• Small insects

These aquatic bugs compete with small fish for food sources. They kill their prey by piercing them and sucking out the bodily fluids.

Water Boatman Food Sources

Water Boatmen are different from Backswimmers because of their food consumption habits.

They lack piercing beaks. Instead, they ingest living material, including:

• Protozoa
• Diatoms
• Nematodes

In addition to these microscopic creatures, Water Boatmen have also been known to feed on algae, mosquito larvae, and small fish eggs.

Their feeding helps maintain dissolved oxygen levels in the water bodies they inhabit. Here is a small comparison table of the two:

Life Cycle and Reproduction

Mating Rituals

Backswimmer

• Backswimmers engage in a unique mating process, whereby the male grasps the female’s thorax with his forelegs.
• The male then produces ultrasonic mating calls to attract the female and initiate copulation.

Water Boatman

• Water boatmen use their modified hind legs to produce sounds by rubbing them against their abdomen.
• Their mating ritual involves the male climbing on the female’s back for a short period.

Egg-Laying and Development

Backswimmer

• Female backswimmers lay their eggs on submerged plants or floating debris.
• The aquatic nymphs develop through a series of instars, molting their exoskeletons as they grow in size.

Water Boatman

• Eggs are attached to underwater plants or debris by female water boatmen.
• Similar to backswimmers, water boatmen nymphs undergo a series of molts before reaching adulthood.

Comparison Table

Both backswimmers and water boatmen can be found in different habitats, such as ponds, lakes, and slow-moving streams. These habitats provide them with suitable locations for their egg-laying and development processes.

Interactions with Environment

Aquatic Ecosystem Roles

Backswimmers and water boatmen are both insects that can be found in various aquatic environments like ponds, lakes, bird baths, and even sewerage ponds. They have different roles in these ecosystems:

• Backswimmers: These insects are predators that feed on other aquatic animals such as mosquito larvae and small fish.
• Water boatmen: They are mostly herbivorous and feed on aquatic plants and living material like algae.

Their presence in water bodies can have an impact on the populations of aquatic animals and plants.

For example, backswimmers can help control mosquito populations in stagnant water by preying on their larvae.

Pest or Beneficial Insects?

Both backswimmers and water boatmen can be seen as a pest or beneficial insect, depending on the situation.

Pest:

• Backswimmers: Their painful bites can cause discomfort to humans, making them undesirable around populated areas such as lake edges or pond-side parks.
• Water boatmen: In some cases, their feeding habits can negatively affect the health of aquatic plants.

Beneficial:

• Backswimmers: As mentioned earlier, they help control mosquito populations by preying on their larvae, which can be beneficial in reducing the spread of mosquito-borne diseases.
• Water boatmen: By feeding on algae and other living material in water bodies, they can help with water clarity and overall aquatic health.

If you have a pond near your home, having a small population of water boatmen can be beneficial to maintain the health of aquatic plants and improve water quality.

Backswimmers and Water Boatmen: Human Experience

Edibility

Interestingly, both backswimmers and water boatmen have been consumed by humans in various cultures:

• Egyptian: Water boatmen are a part of some Egyptian dishes
• Mexican: Backswimmers are considered a delicacy in some Mexican cuisine

Cultural Significance

Although these aquatic insects may seem unimportant, they have cultural significance and have been mentioned by various researchers, such as Dr. Gilbert Waldbauer, who studied their roles in aquatic ecosystems.

Conclusion

To summarize, while backswimmers and water boatmen both have oval-shaped bodies, long legs, and one pair of wings, they are very different in other ways.

Backswimmers swim upside down and have a keeled back, while water boatmen swim right side up and have a flat back.

Backswimmers are predators and prey in the aquatic food chain, while water boatmen are mostly herbivores and detritivores.

Backswimmers can bite humans if handled or disturbed, while water boatmen are harmless to humans.

Backswimmers and water boatmen are interesting and important animals that reflect the diversity and adaptation of life in water.

Footnotes

1. [common backswimmer – Entomology and Nematology Department](https://entnemdept.u ↩