It is a strange way to move forward!
Rugby is a strange sport. I played it a few times but decided that it was more fun for me to watch it on TV. My sons, however, were members of a local rugby team and loved the sport. The basic rule of the game is that in order to move forward on the pitch, you throw the ball backward. The players themselves don’t have to move backwards though, but they can, of course, if they want to. Some animals cannot.
As if they lacked the necessary programme for reversed motion, most caterpillars can only crawl forward. When they want to move back, they have to make a 180-degree turn (a U-turn). The legs of adult insects and spiders, too, are “wired up” in such a way that backward stepping becomes impossible. Yet, it has nothing to do with the fact that insects have six, spiders have eight and we have two legs. The centipede Geophilus sp. has over a hundred pairs of legs and can switch them into forward or backward gear at will and 10-legged crabs as well as lobsters can move forward and also sideways very well.
Horses, cows, cats (especially when a hood covers their head and eyes) are all quite good at stepping backwards, but nobody beats the squid. This tentacled creature habitually swims backwards at great speed and may even breach the water to make backward leaps of several metres. The technique of backwards-jumping (but this time just underwater) is also employed by, for example, rock lobsters, the octopus, and scallops in order to escape from a predator. Insects that do not have this option would either drop down or as mentioned above seek a way to turn around and flee in a forward direction, but away from the disturbance.
Darting forwards and backwards with lightning speed is the method by which male swordtail fish try to impress, perhaps even enthral, their females. But to what extent the latter, who never swim backward, even notice the males’ escapades, I still don’t know despite having watched the swordtail’s courtship in my aquarium and been captivated by it innumerous times.
Another species of fish, known by the discourteous name of “assfish” , also uses backward motion to wriggle into place when entering its sea cucumber’s host’s rear body opening (hence its vulgar name) and earthworms in their burrows, too, are adept at sliding forward or backward. When we turn our inquiring eye skyward, we notice that hoverflies and dragonflies and to some extent bumblebees and honey bees as well are capable of backward flight. Amongst our feathered friends, the hummingbird undoubtedly will carry away the prize as the best backward flyer. Come to think of it, having competitions for backward running and backward jumping in the Olympic Games mightn’t be such a bad idea and would have perhaps made more sense than having baseball added to the Games (or am I alone with this opinion?).
© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2019.
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