Pond Skating Insects Reveal Water-Walking Secrets

In a new article, science writer Stephen Ornes explains how pond skaters effortlessly skip across water leaving nothing but a small ripple in their wake.

As Ornes writes, our current understanding of the mechanisms adopted by the pond skater is down to the efforts of David Hu, who as a mathematics graduate from the Massachusetts Institute of Technology spent four years studying their behaviour.

Reveal-Water-Walking-Secrets

In a new article, science writer Stephen Ornes explains how pond skaters effortlessly skip across water leaving nothing but a small ripple in their wake.

Hu, along with his PhD supervisor John Bush, found that pond skaters use the middle of their three pairs of legs to “row” across the water. When a rowing boat’s oar slices the water, it creates swirling vortices just beneath the surface that twist away from the boat and move it forwards — the same vortices are created by tiny hairs that cover the pond skater’s legs. Read more

First Robot That Mimics the Water Striders’ Jumping Abilities

The first bio-inspired microrobot capable of not just walking on water like the water strider — but continuously jumping up and down like a real water strider — now is a reality. Scientists reported development of the agile microrobot, which could use its jumping ability to avoid obstacles on reconnaissance or other missions, in ACS Applied Materials & Interfaces.

First-Robot-That-Mimics-the-Water-Striders

The first bio-inspired microrobot capable of not just walking on water like the water strider – but continuously jumping up and down like a real water strider – now is a reality.

Qinmin Pan and colleagues explain that scientists have reported a number of advances toward tiny robots that can walk on water. Such robots could skim across lakes and other bodies of water to monitor water quality or act as tiny spies. However, even the most advanced designs — including one from Pan’s team last year — can only walk on water. Pan notes that real water striders actually leap. Making a jumping robot is difficult because the downward force needed to propel it into the air usually pushes the legs through the water’s surface. Pan’s group looked for novel mechanisms and materials to build a true water-striding robot. Read more

Water: Physical properties of water

We live on a planet that is dominated by water. More than 70% of the Earth’s surface is covered with this simple molecule. Scientists estimate that the hydrosphere contains about 1.36 billion cubic kilometers of this substance mostly in the form of a liquid (water) that occupies topographic depressions on the Earth. The second most common form of the water molecule on our planet is ice. If all our planet’s ice melted, sea level would rise by about 70 meters.

Drops_Imapct

Water is also essential for life. Water is the major constituent of almost all life forms. Most animals and plants contain more than 60% water by volume. Without water, life would probably never have developed on our planet.

Water has a very simple atomic structure. This structure consists of two hydrogen atoms bonded to one oxygen atom (Figure 1). The nature of the atomic structure of water causes its molecules to have unique electrochemical properties. Due to the way in which the hydrogen atoms are attached to the oxygen atom, the hydrogen side of the water molecule has a slight positive charge. On the other side of the molecule a negative charge exists. This molecular polarity causes water to be a powerful solvent and is responsible for its strong surface tension. Read more

Water: Hydrologic cycle

The hydrologic cycle is a conceptual model that describes the storage and movement of water between the biosphere, atmosphere, lithosphere, and the hydrosphere (see Figure 1). Water on our planet can be stored in any one of the following major reservoirs: atmosphere, oceans, lakes, rivers, soils, glaciers, snowfields, and groundwater. Water moves from one reservoir to another by way of processes like evaporation, condensation, precipitation, deposition, runoff, infiltration, sublimation, transpiration, melting, and groundwater flow.

hydrocycle-hires

The oceans supply most of the evaporated water found in the atmosphere. Of this evaporated water, only 91% of it is returned to the ocean basins by way of precipitation. The remaining 9% is transported to areas over landmasses where climatological factors induce the formation of precipitation. The resulting imbalance between rates of evaporation and precipitation over land and ocean is corrected by runoff and groundwater flow to the oceans. Read more

Robotic fish learns to navigate currents and turbulence in water

Robotic-fish-learns-to-navigate-currents-and-turbulence-in-waterThe goal of making robotic fish is to make them as functional as real fish but with the added sensors that humans want for detecting pollution, data about water, and so on.

But to get there, they need to have the sensors fish naturally have — including lateral line sensing. This is how fish detect and use flow features like currents in water.

Tallinn University of Technology reports, “Though flow is a highly volatile and unsteady state of matter, it can nonetheless be measured and characterized based on many salient features that do not change much in space and time (such as flow direction or turbulence intensity, for example)”. Read more