How many times can a worm be split in half and still grow back?

Thursday 29th July 2010
Uploaded by: nikkiwithers
Asked by: MARTIN HARRISON, BY EMAIL

To a biologist, ‘worm’ refers to many, quite different organisms. The ability to re-grow body parts differs enormously between them, although tails are generally easier to re-grow. If you mean earthworms, their tails usually die when severed, while for many other species the head portion (down to the ‘saddle’) can re-grow a tail – although often a stunted one. Some species can also regenerate the very front of the head.
My guess is certain earthworms could fully regenerate from one specific quarter of their body, although it’s not really known and cruel to try and find out – most would end up dead or stunted.
Some non-British earthworms can even repeatedly re-grow lost tails, although other segmented worms beat that: many reproduce asexually by severing themselves repeatedly, and parchment worms can entirely regenerate from just their 13th body segment.
However, the distantly related planarian flatworms have more extraordinary regenerative powers. Some Dugesia species can fully re-grow from random body fragments of about 10,000 cells: approximately 1/20th of the adult body size. 

GOT A QUESTION?

Scratching your head over a burning scientific conundrum? submit your question and we'll get our esteemed panel of experts to answer it for you.

 

Do whales sleep?
previous Q&A Article
What is the largest animal ever eaten by a Venus flytrap?
next Q&A Article
Q&A Tabs

Both fats and oils are molecules shaped like a capital E with a glycerol spine and arms made of fatty acid chains. In animals, the carbon atoms in the fatty acids are saturated with hydrogen atoms...

The world's nuclear reactors have generated tens of thousands of tonnes of high-level nuclear waste, and the current solution is to simply store the stuff. This is not without its dangers: an...

That depends on what you mean by life. If you mean life as we know it, the best bet is Mars, as it’s the most Earth-like of the other planets. But even the Earth is home to so-called...

All female mammals have a clitoris, the sole purpose of which is to react to sexual stimulation, and presumably this stimulation has evolved to be pleasurable for most species. But establishing...

To create a sound, we have to set matter - whether it's a gas like air, a liquid or even a solid material - in regular motion, creating a wave of specific frequencies, which we hear as a sound of...

Mirrors don’t reverse left and right either – that’s just our interpretation of what happens. Your reflection in the mirror is actually reversed front to back – if you have...

Discovered by an American student named Gary Flandro in the mid-1960s, the slingshot manoeuvre usually involves spacecraft briefly 'coat-tailing' a planet orbiting the Sun, extracting some of the...

The ice disappears because the wind blows away water molecules that have evaporated or 'sublimed' from the ice, so the ice slowly shrinks in size. The molecules that escape are those with the...

We use cookies to improve your experience of our website. Cookies perform functions like recognising you each time you visit and delivering advertising messages that are relevant to you. Read more here