Every so often, my adopted cat brings home geckos in two pieces, namely the still-moving tail and the rest of the body (also still moving). But there is never any obvious blood. Why?
• Wild animals often must recover from severe injuries, or die. Where we live, I am repeatedly amazed to see game birds survive incidental injuries and regain normal use of loosely flapping broken legs or wings that had been very crooked.
The realities of natural selection are so extreme that many snakes, insects, fish or birds have developed highly effective self-healing abilities. As a result, they can afford to try to redirect attacks towards non-critical areas at their rear, in particular frills of hair, loosely set feathers, fake heads – or, indeed, sacrificial tails. Some animals even use their tail non-sacrificially to attract prey.
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Many lizards have more or less fragile tails that distract predators by thrashing when broken off. If alarmed, some geckoes drop their tail whether or not something is tugging at it, an example of what is known as autotomy.
A tail is a major investment, served by its own artery. Letting it bleed would be fatal, so muscles at intervals along the blood vessels clamp the flow, and the blood clots rapidly. It is something surgeons can only envy.
Jon Richfield, Somerset West, South Africa
• Many lizards and geckos display this behaviour, which is known as autotomy. Where I live, there are no geckos but lots of wall lizards, which shelter in and around the garden. Occasionally, just moving one of my outside bins will reveal a wriggling tail, the startled lizard having made off.
My cat loves hunting lizards and has brought in tails – although less often now – but never both the tail and its owner together. The lizards do grow a new tail, but it lacks vertebrae and clearly doesn’t match the rest of the body.
Terence Hollingworth, Blagnac, France
• In Hawaii, I see geckos hunted by cattle egrets (both are invasive species there). The egrets walk on the tops of hedges and reach down to grab geckos with their beak. If one gets hold of the tail, I frequently see the gecko fall away, leaving the egret with only a tail in its mouth. If it grabs the body, the egret must still twist the gecko 90 degrees to swallow it, and so may still end up with just the tail.
Stephen Johnson, Eugene, Oregon, US
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