The Naked Scientists

The Naked Scientists Forum

Author Topic: Why do cicadas have a 17 year lifecycle?  (Read 16004 times)

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Why do cicadas have a 17 year lifecycle?
« on: 15/08/2007 22:39:10 »
Life is for living yes ?

Now as far as I understand this beasty:



The Cicada, lives underground in some kind of stasis right ?...I know that some stay underground for as long as a seventeen year cycle !

This is what happens....cicada wakes up...burrows upwards....finds a mate..does the deed...then dies !!....

...Mummy goes and lays some eggs....then dies.....

...babies hatch.....burrow into ground.......go to sleep for seventeen years ! (or what ever the length of that particular cicadas cycle is for)


What I want to know is why do all this ?...it's not much of an existence is it ?
...other insects do it too don't they ?..Mayfly's ?...

...what is the point of living , if living is just to procreate for a few minutes and then die ?

« Last Edit: 03/04/2008 11:03:06 by chris »


 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #1 on: 19/08/2007 04:49:31 »
Not all Cicadas live such an abbreviated life cycle - from our perspective. If you realize that most of the over 2000 species don't hibernate or go dormant when underground , but actually feed and burrow and go through at lease two nymph stages.

So, there is a little more to it than just sex and death.
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #2 on: 19/08/2007 14:25:47 »
Thanks Jim.

Cripes !..there's really 2000 species of cicada !!

In the case in question though there must be quite a long stage or dormancy but i take your point and thank you for answering it. I forgot I'd asked it !

 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #3 on: 19/08/2007 17:54:10 »

This is what happens....cicada wakes up...burrows upwards....finds a mate..does the deed...then dies !!....


Sounds like a student
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #4 on: 19/08/2007 20:15:25 »

This is what happens....cicada wakes up...burrows upwards....finds a mate..does the deed...then dies !!....


Sounds like a student

LOL  ....won't students also be tanked up on beer and pot ?
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #5 on: 19/08/2007 20:18:39 »

This is what happens....cicada wakes up...burrows upwards....finds a mate..does the deed...then dies !!....


Sounds like a student

LOL  ....won't students also be tanked up on beer and pot ?

Yes
 

Offline showmen

  • Jr. Member
  • **
  • Posts: 21
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #6 on: 23/08/2007 01:46:20 »
You seem to be asking two questions there- firstly what's the "point" of life for them


...what is the point of living , if living is just to procreate for a few minutes and then die ?



I would think you've just answered your own question there. If they procreate, their offspring will survive- hence they will stay around for another generation or more.

Secondly, you seem to be asking, why bother laying dormant for so long?

JimBob rightly pointed out that not all Cicada species behave in this way.

To answer your question, there is a principle in evolutionary biology to explain some instances of living in groups which is called the "dilution effect"- i.e. if the cicadas emerge in huge numbers at the same time(which they do)the chance of any one cicada being eaten by a predator is reduced.

But the question still remains- why remain dormant for 17 years? Well, in fact there are 13 and 17 year life cycles. So, what's significant about 13 and 17? First of all, the advantage of a long dormant stage is that it forces specialist predators to become dormant themselves or to switch their preferred food. But why not 20 years or 15 years? There has been some speculation that 13 & 17 are significant because they are prime numbers so that a predator could not regularly fall into sychrony with cicadas if it had a short life cylce of which the cicada life cycle is a multiple. If the cicadas had a 15-year lifecycle, predators with 3 or 5 year life cycles would fall into step with their prey every third or fifth generation.
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #7 on: 23/08/2007 04:47:55 »
THANK YOU showmen (and welcome to the site)
Fascinating insight you have shared and I am grateful for it.

I know it seems that I may have answered the first part of my question but I do still not see the point of existing when existence is monopolised by procreation...and procreation only !.....BUT...perhaps I need to be a cicada to truly understand the nature of it and my mistake is to apply a human equation to my question.

It's great to have you on board....please stick around and THANK YOU.
 

Offline showmen

  • Jr. Member
  • **
  • Posts: 21
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #8 on: 23/08/2007 15:20:42 »
THANK YOU showmen (and welcome to the site)
Fascinating insight you have shared and I am grateful for it.


thanks. it seems like a cool forum. it's not my insight though-i should have mentioned my source actually now that i think of it - J.R. Krebs & N.B. Davies- An introduction to Behavioural Ecology Chapter 6 ,3rd Ed.
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #9 on: 23/08/2007 16:17:45 »
THANK YOU showmen (and welcome to the site)
Fascinating insight you have shared and I am grateful for it.


thanks. it seems like a cool forum. it's not my insight though-i should have mentioned my source actually now that i think of it - J.R. Krebs & N.B. Davies- An introduction to Behavioural Ecology Chapter 6 ,3rd Ed.

Well, I am still grateful you took the time to respond.

we're a friendly bunch and I think from what I have seen so far that you are more than welcome here.

I appreciate the reference source.
 

Offline dkv

  • Sr. Member
  • ****
  • Posts: 299
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #10 on: 17/09/2007 18:57:13 »
Life is for living yes ?

Now as far as I understand this beasty:



The Cicada, lives underground in some kind of stasis right ?...I know that some stay underground for as long as a seventeen year cycle !
REP: This is not true .... seventeen years doesnt make any sense.  What purpose can such a long hibernation serve .... If animals do not make use their physical abilities then they loose. FOr example if child since birth is kept under dark for  few months then he or she will go blind.
This applies to Cicada life cycle as well.
Moreover other benefits of hibernation includes safety
during a period of metamorphisis ... from physical state to another... but 17 year underground and doing nothing doesnt make any sense.
The size of insect is too small to demand such a strategy... they can easily overcome the security problem with greater number of eggs.
The eggs will easily run out of fuel in 17 years if the food is biological.

If the research is still true then it means that they have live a life underground... and do NOT intend to replicate for maximum period of time. Therefore the best strategy to do so is to reduce the metabolism to minimum thus slowing down the biological clock.
But why ?
THIS Strategy suggest desire to experience maximum pleasure ...(by reducing the frequency .. greater the frequency more mechanical the species is)
==============================

This is what happens....cicada wakes up...burrows upwards....finds a mate..does the deed...then dies !!....

REP: THIS WHAT TSP results into...
========================================
...Mummy goes and lays some eggs....then dies.....

...babies hatch.....burrow into ground.......go to sleep for seventeen years ! (or what ever the length of that particular cicadas cycle is for)
REP: Again sleep is not a sleep of usual kind ... it is a sleep to develop a system which can experience greater pleasure than its ancestor.
=======================================

What I want to know is why do all this ?...it's not much of an existence is it ?
...other insects do it too don't they ?..Mayfly's ?...

...what is the point of living , if living is just to procreate for a few minutes and then die ?

REP: THOSE FEW MINUTES IS LIFE..What matters for a life form is experience and not replication.
 ===========================================

Cheers

 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #11 on: 17/09/2007 19:58:42 »


REP: THOSE FEW MINUTES IS LIFE..What matters for a life form is experience and not replication.
 ===========================================
[/b]
Cheers


So why experience a life of just a few minutes ?
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #12 on: 17/09/2007 20:51:07 »
Quote
REP: THOSE FEW MINUTES IS LIFE..What matters for a life form is experience and not replication.


Do you believe this true of all life forms, includings humans, that it is the experience?
 

Post by dkv click to view.

Offline dkv

  • Sr. Member
  • ****
  • Posts: 299
    • View Profile
Re: Why do cicadas have a 17 year lifecycle?
« Reply #13 on: 17/09/2007 21:05:37 »
Shrunk
Why only few minutes?
REP: Life doesnt offer perpetual systems.That will against laws of thermodynamics. There are costs asscoiated with it.
=================================

Quote
REP: THOSE FEW MINUTES IS LIFE..What matters for a life form is experience and not replication.

Do you believe this true of all life forms, includings humans, that it is the experience?
REP: The theory says that as the species move towards
greater pleasure it increases the net fitness level of the Group to experience more stable forms of Pleasure signal.. in english it is called Happiness or contentment.
Happiness(if that is culturally relevant) stays longer. Humans create strategies for this sustainable pleasure.Humans experience is more stable and continuos because of the reasons I described.
Does that make any sense?
 

The Naked Scientists Forum

Re: Why do cicadas have a 17 year lifecycle?
« Reply #13 on: 17/09/2007 21:05:37 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums
 
Login
Login with username, password and session length