Hot day. A bee buzzes for a drink in a nearby lake, but oh no! Its wings just connected to the surface of the water; now it is stuck and aerodynamics are no longer an option. Is she safe?
According to the best estimates of scientists, the bee has only minutes before gravity threatens to pull it into the depths. But that's enough time – given the unique biocomputing strategy, the species of bees seems to have evolved.
In a new study, Kaltech researchers have identified a convenient bee for survival tactics ( Apis mellifera ) that can be used to escape from this type of wet difficulty: by running yourself through the water, using its wings to generate wool – a behavior never before documented in insects.
"The movement of the bee's wings creates a wave that her body is able to ride forward," says biomechanics engineer Mortez Garib.
"Seaplanes or surfboards."
The genesis of this strange discovery lies in the accidental observation by the co-author of Gharib, the scientific engineer Chris Ro, who one day just happened to observe a bee stuck in water in a still pond to the Caltech campus.
As Roh watched, he saw the bee's beating wings generate small waves behind him on the surface of the lake. Was that intentional, and if so, how did it work out?
To get a better idea of physics, Roch quickly pulled out a bee (now an unwilling research volunteer) and brought it to the water lab.
There, with Gharib, the two scientists tested him – and 32 other individual bees – in experiments where their water could be studied closely.
Recording bees waving in a pan full of water and capturing activity with slow cameras – researchers keep the secret of a bee lake exit strategy.
"Bees use their wet wings as hydrophols to propel their water surface," researchers write in an article on the phenomenon.
"Their locomotion gives a hydrodynamic impulse to the surrounding water in the form of asymmetric waves and a deeper water jet stream generating ∼20-µN average thrust."
(This is approximately 20 million Newton in terms of ms of force which means it's actually a pretty energy-efficient way to get around the water.)
Other insects such as honey bees and water lilies use different types of water movement called surface skimming. However, bees cannot do the same because when their wings touch the water, the underside of the wing sticks to it, and they cannot swing across the surface with enough force to clear the water.
Fortunately, the hydrophilic technique – aided by the way bees angle their wings while rocking up and down (to minimize it, then minimize contact with water as they press and then pull out their wings) is enough to move at three body lengths per second.
Experiments have revealed that bees cannot sustain the movement of hydrophore indefinitely, however – after about 5 minutes, they appear to show signs of muscle fatigue (probably because of how much harder it is to swing your wings against liquid water.
However, in a small enough pond, which is probably long enough for you to surf for safety, then just climb up when you reach Terra firma.
"When the bees were placed on the surface of local pond, they were able to invade they go ashore and get out of the water, "the authors write.
" Once out of the water, they dry out for a short time and fly away. "
The discoveries were respected in PNAS .