Nature Olympics : Aquatic Events

In honour of the summer Olympics, we thought we’d profile a few of our own natural athletes – the fauna that can be found in Ontario present some incredible contenders! If Mother Nature was to pit some of her sports players against humans, we suspect our multi-legged and feathered friends would be the ones winning all the cereal endorsements.

First up, the aquatic events.

Predacious Diving Beetle – Coelambus impressopunctatus by Stephen Luk

High dives and deep dives, this sport is unique for its combination of ability within two media – water and air. The first competitor up to the board is the predaceous diving beetle. The Dytiscidae family have some 500 members in North America, and come in a range of muted colours such as brown, dark green and black with varying patterns. They live in freshwater ponds or still-water areas, where their entire lifecycle can occur. Adults inject eggs into underwater plant material, while hatching larvae pupate in moist soil. The adults are air-breathing but dive under the water to catch their prey. These beetles eat other larvae, tiny fish and other small insects. Catching air pockets beneath their wings enables them to stay underwater, and powerful hind legs propel them downwards. A distinctive trait of this family is that the hind legs move simultaneously like those of a frog. If the beetle hasn’t a full enough stomach, it must sometimes ingest water and then propel it from its rectum in order to escape surface tension. Jet-propelled action!

Water striders. Photo from Resources for Rethinking, a Canadian not-for-profit with nature education resources for teachers.

Across the surface, the best-known medal contender for the rowing category would be the water strider, or Gerrid. Skimming across the surface of calm water as though they were ice dancers, water striders use their middle legs for rowing and their hind legs for steering. The rowing legs push down and outwards, creating a semi-circular wave that propels them forward at speeds that can reach up to one metre a second or more! Water striders manage to stay on top of the water by spreading their body weight over a large surface area through using their long legs. These same legs can flex with water movement to keep the insect above water. The body is covered with numerous small hairs that trap air pockets should the strider be covered with a wave or water. In this fashion the insect can reach buoyancy again quickly rather than be drawn down and trapped by surface tension. Physics give the water strider its competitive edge!

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