Do spiders survive if thrown from a height out of a window?
Hillary Shaw
Newport, Shropshire, UK
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In simple terms, an object’s speed when falling through air depends on its shape and weight. For us, the highest, or when falling near Earth’s surface is about 200 kilometres per hour, but for a cat it is nearer 100 km/h and for a squirrel about 40 km/h.
Spiders vary in size and weight, but assuming that a spider weighs about 3 milligrams and has a cross-sectional area of around 100 square millimetres, it will reach a terminal velocity of around 0.7 metres per second, which is a slow human walking pace. The spider can probably withstand hitting the ground at this speed, while grass and leaves may cushion its impact.
However, it may emit some web that can act as a parachute, and this, together with its non-aerodynamic shape, means that it won’t reach its terminal velocity anyway.
[Ed – to be on the safe side, why not release spiders onto the window sill instead of flinging them out?]
Colin Oatway
Wokingham, Berkshire, UK
The picture that accompanied this question when it was first posed (21 November) showed a pinktoe tarantula, Avicularia avicularia. Tarantulas aren’t true spiders (one difference is that true spiders have six silk-producing spinnerets, whereas tarantulas only have two).
There are two types of tarantula: arboreal (tree dwelling) and terrestrial (ground dwelling). For the tree-dwelling types, any fall from even a metre or so onto a soft surface can be fatal. This is because the impact can split the abdomen, resulting in massive blood loss.
As a consequence, keepers tend to keep tarantulas in containers with a low ceiling, and filled with lots of earth, so that if the tarantula does climb to the top and fall, there is a good chance that the impact won’t damage the abdomen too much.
I don’t know as much about true spiders, but they can travel long distances by spinning out a web thread to catch the wind, a process called ballooning. Some spiders have been found ballooning more than 3 kilometres up in the atmosphere. Due to their low weight compared with body surface area, and the thread acting as a parachute, a true spider should survive a fall. However, if it is a type of house spider, it may not survive outside regardless of any issues with falling.
Lachlan Jones
Brisbane, Australia
This question reminded me of an occasion when I found a big huntsman spider in a mop bucket. I banged out the bucket over a balcony rail and the spider floated off in the breeze on a silken thread.
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