Multimodal Aquatic Hexapods Use Hybrid Walking-Swimming Gaits in Shallow Water

Area of Science:

• Biomechanics
• Evolutionary Biology
• Robotics

Background:

• Animals exhibit diverse locomotor strategies for transitioning between aquatic, aerial, and terrestrial environments.
• Insects capable of both underwater and land locomotion offer insights into amphibious mechanics.
• Understanding these transitions is crucial for evolutionary studies and bio-inspired designs.

Purpose of the Study:

• To investigate how aquatic hexapods (Dytiscidae and Notonectidae) adapt their locomotion when moving from dry land to shallow water.
• To quantify gait changes at different water depths.
• To explore the underlying mechanics of amphibious locomotion in insects.

Main Methods:

• High-speed videography was employed to capture insect movement.
• Kinematic tracking was used to quantify gaits.
• Locomotion was analyzed at varying water depths (below, at, and above body height).

Main Results:

• On land, diving beetles use an alternating tripod gait; backswimmers use anterior legs for crawling.
• In shallow water, both species exhibit hybrid gaits with synchronous swimming strokes (metathoracic legs) and walking (anterior legs).
• At water levels above body height, insects switch to full swimming using metathoracic legs.

Conclusions:

• Locomotion strategies adapt to competing forces like water resistance, buoyancy, and ground reaction.
• Limb coordination is tuned for transitional environments and across interfaces.
• Findings provide insights into insect locomotion and inspire amphibious device design.