|How come geckos have the ability to regenerate
limbs and tails but can still pass away from
|Question Date: 2017-09-30|
What a great question! There are actually
multiple levels of regenerative abilities
in animals, and this is a huge area of research
for scientists. Some animals have remarkable
regenerative abilities, like one called
botryllus, can regenerate entirely from
a single tiny piece of blood vessel. The worm
planarian can be cut in half and both
halves will regenerate to create two whole new
animals! The better-known starfish can
regenerate from a single limb!
Geckos can regenerate their limbs and
tails (but we humans cannot!). However,
geckos cannot regenerate everything.
Regeneration in geckos follows a similar pattern
to how geckos grow and develop – how the limbs and
tails are created when a baby gecko is forming!
But geckos, which are vertebrates (meaning they
have vertebrae/boney structures inside!) are
higher up on the evolutionary tree than those
other animals described earlier, and higher
animals have lost their ability to regenerate
their entire body because of their complexity.
Therefore, despite having the ability to
regenerate their tail, if the damage is too
severe, these abilities will not save the gecko
and it can still die from internal bleeding.
Thanks for the great question!
If a gecko didn’t regenerate its limbs it would
probably still survive. Before the limb is
regenerated, the wound is already sealed.
Therefore, the limb is regenerated for future
survival, since it will be easier for it to
find food and escape from predators if it
regenerates lost limbs. The lost limbs are
regenerated using a similar process to how the
limb was generated in the first place when the
gecko was an embryo.
Internal bleeding is when blood vessels rupture,
spilling blood into the internal cavities. Unlike
the loss of limb, this poses an immediate danger
and the slow process of limb regeneration won’t
Additionally, the blood vessels are present
throughout the entire body which makes it way more
complicated than re-growing an appendage in one
place. The loss of blood alone can kill the
gecko, or pressure of the blood can compress its
organs. Think about it this way, if you lose a
finger or even an arm you can survive, but if your
organs are severely damaged, you often can’t
It's a question of how much damage you inflict.
If you cut a gecko in half, it will die,
because you will have done too much damage to its
important organs. Limbs and tails are important
for moving around, but aren't so important for
just living, so the gecko can regenerate them.
Everything that is alive will die. It makes sense
that geckos and some other reptiles can lose a
tail or limb, and there's not too much blood loss;
and they can regrow the tail or limb. Once I was
digging in my garden, and I cut the tail off a
little lizard and the tail wiggled and wiggled in
my hand for maybe 15 seconds. I think that's how
long it took for all the chemical energy in the
tail to be used up.
But there's more blood in the internal
organs, and so if those start bleeding, the
gecko dies, just like all living things die when
they are too badly injured.
Geckos are able to regenerate their limbs and
tails because those processes are governed
differently than internal bleeding. Check out
this video of a leopard gecko tail regeneration!
DO NOT FORGET TO SKIP THE AD IN ORDER TO WATCH THE
Great question. The ability to regenerate limbs
and tails is pretty awesome. Scientists are very
interested in this because allowing people to
regrow even a finger is currently not possible.
The answer to this mystery probably has to do with
turning on certain genes in the stump of the
limb or tail.
Every cell in our bodies (except mature red
blood cells and sex cells) has a complete set of
DNA, but only certain genes are switched on at
certain times, depending on the age of the cell
and where it ends up. Our cells get locked into
certain “jobs” pretty early, so the cells in
our wrists won’t turn into cells that will make a
But why do geckos bleed to death from internal
injuries? Well, that’s a different process
from limb growth. Limb regeneration takes a
really long time. It can take weeks or months,
depending on things like the amount of damage,
nutrition, and temperature. Bleeding has to
stop pretty quickly, in seconds or minutes. We
have clotting factors in our blood that get
activated when our tissues are damaged. The tissue
sends out a chemical signal. If all goes well,
a plug of tiny fibers and platelets (pieces of
a special kind of blood cell) forms in the
tear, making a sort of patch until new cells
can replace the damaged ones. If the damage is
too bad, the plug can’t form or can’t form soon
enough. The process is probably similar in geckos.
Why do you think the ability to regenerate
limbs is pretty common in reptiles and amphibians,
but not possible in mammals?
Thanks for asking,
Blood serves a number of functions that are
necessary for an organism to live, including
transporting oxygen around the body and
bringing white blood cells which are involved in
fighting infections/diseases. If an organism
loses enough blood, these functions cannot be
properly executed, and the organism will lose its
life. Hope this helps!
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