Concealed in the weed beds, the ranatre patiently awaits its prey. Under the frightened eyes of the children who observe the fascinating life of the aquatic world.
The "twig" bug of fresh water
It carefully moves its long body, 35 mm, on its 6 long legs, in the middle of aquatic plants. Water is its element. Like a twig, it remains motionless, observing its environment with its large round eyes. She captures her preys with her front legs transformed into ravenous claws, piercing them with her biting and sucking rostrum. The ranatre, Ranatra linearis, insect of the family Nepidae, is none other than an aquatic bug, known as heteropteran, a formidable predator of calm waters, common in the entire Palearctic zone.
It breathes oxygen from the air...under water
The ranatre lives, hunts, reproduces, under water. But it has neither gills nor breathing membranes. Then to find its oxygen it is equipped with a tuba. The end of its abdomen is extended by a long tube, made up of 2 half-stems with gutters, just as long as its body. This respiratory siphon links it to the air, allowing it to feed its tracheal system in air. It prefers to hunt close to the surface, in order to get regular supplies with less effort.
A carnivore on the lookout
At length of respiratory siphon of the surface, twig in the grasses, the ranatre settles and does not move any more. She waits. Aquatic insects, larvae, small crustaceans, tadpoles, and even small fish, are on its menu. If they pass within its reach, its legs fold up on the prey, hold it in a vice, hook and spine effectively close it. The continuation is terrible for the catch. And the observer. Seeing a small tadpole being pierced by the rostrum of the ranatre, being predigested, then absorbed by the hunter, is impressive, and not belonging to this small world is rather reassuring...
A clumsy swimmer
If the ranatre lives under water, swimming is not really her domain. It prefers to move at its own pace from plant to plant, hanging on with its long legs, which are not equipped with swimming bristles like its cousins the Notonectes and Naucores. And if it does not swim, or badly, it is able to leave water, to let itself dry, and... to take its flight. She spreads her wings, of a beautiful translucent blue, and leaves in search of new territories. Surprisingly, she reveals a red abdomen of the most beautiful effect, unexpected under her yellowish colors.
Males and females, aquatic meetings
The reproduction of ranatres takes place in spring. The female pierces the plants with her caudal auger and deposits eggs of about 2 mm, either scattered or in a line, depending on the plants chosen or available. 2 small air filaments are visible to the naked eye. At the hatching, the small ones resemble the adults, 5 larval stages will follow one another during 2 months to lead to the ranatre of final size. Which will live approximately 2 years.
If the ranatre is impressive when it captures its preys, to observe it cleaning itself delicately with its front legs, to stiffen like a twig, to deposit a line of eggs on a water lily, to fly away all colored, is a spectacle of which one does not get tired.
