How many molts?

[mikeymig]

 question  - How many molts do you think it would take an Eldredgeops to go from 11mm (.43") to 64mm (2.52")?

[Kane]

Chatterton and Speyer (1997) estimate that the process of ecdysis occurred between 8 to 30 times during a trilobite's life. Of course, pinning down a precise number on the basis of the size of the moults probably would be problematic, as one might also have to consider unique differences (i.e., just as any other organisms of the same species and age may differ in size). 

[Walt]

Here is an informative article on molting in Trilobites.  Unfortunately it does not provide an answer to your question....

Thanks for asking it though.  I learn something new every time.

 

@piranha I don't know if you have this or not...I did not see it when I searched.

Recognising moulting behaviour in.pdf

[mikeymig]

The sites I collect at here in NY, Eldredgeops are not common and the local population is a classic bell shaped curve. I was always curious if I could guesstimate their age based roughly on size like lobsters. 

 

This molting, or shedding, occurs about 25 times in the first 5-7 years of life. Following this cycle, the lobster will weigh approximately one pound. After this time, the lobster may then only molt once per year (males) or once every two years (female). At this point, with each molt the lobster will increase about 15% in length and 40% in weight. No one has yet found a way to determine the exact age of a lobster. However, based on scientific knowledge of body size at age, the maximum age attained may approach 100 years. Lobsters can grow to be 3 feet or more in overall body length. The University of Maine

 

Thanks

[Walt]

4 minutes ago, mikeymig said:

The sites I collect at here in NY, Eldredgeops are not common and the local population is a classic bell shaped curve. I was always curious if I could guesstimate their age based roughly on size like lobsters. 

 

This molting, or shedding, occurs about 25 times in the first 5-7 years of life. Following this cycle, the lobster will weigh approximately one pound. After this time, the lobster may then only molt once per year (males) or once every two years (female). At this point, with each molt the lobster will increase about 15% in length and 40% in weight. No one has yet found a way to determine the exact age of a lobster. However, based on scientific knowledge of body size at age, the maximum age attained may approach 100 years. Lobsters can grow to be 3 feet or more in overall body length. The University of Maine

 

Thanks

They keep molting until they die.  And to my knowledge, no one has been able to establish a life span for trilobites.  There are a lot of the above variables missing, so I doubt you could come to more than a guess.  I'm sure someone out there has tried, though.  I will have to look if someone with the answer does not beat me to it.

[piranha]

5 hours ago, Walt said:

@piranha I don't know if you have this or not...I did not see it when I searched.

Recognising moulting behaviour in.pdf

 

Search again lol   ...and another excellent paper by the same authors:

Daley, A.C., & Drage, H.B. 2016

The fossil record of ecdysis, and trends in the moulting behaviour of trilobites. 

Arthropod Structure & Development, 45(2):71-96   PDF LINK

[Walt]

I seem to have a lot of trouble with the search function.....either there are no results, or 12,000 results.  I suspect operator error

Maybe I will hone my skills by searching for a thread on searching....

 

Thanks!

[thelivingdead531]

[Walt]

[digit]

17 minutes ago, thelivingdead531 said:

The world may never know

...to get to the Tootsie Roll center of a Tootsie Pop?

 

http://tootsie.com/howmanylick-experiments

 

I'm glad I'm not the only one who's mind went here when I first read this topic. I thought I was an oddball for a moment.   Wait? What?

 

 

Cheers.

 

-Ken

[Walt]

[daves64]

25 minutes ago, digit said:

...to get to the Tootsie Roll center of a Tootsie Pop?

 

Cheers.

 

-Ken

1 ..... 2 ........ 3 .......... *crunch* OUCH! (note to self.. stop licking the Tootsie Pop before biting it) 

 

As for the molts... 42 (the Ultimate Answer according to the Hitchhikers Guide to the Galaxy) 

[thelivingdead531]

14 hours ago, digit said:

...to get to the Tootsie Roll center of a Tootsie Pop?

 

http://tootsie.com/howmanylick-experiments

 

I'm glad I'm not the only one who's mind went here when I first read this topic. I thought I was an oddball for a moment.   Wait? What?

 

 

Cheers.

 

-Ken

I couldn’t help it, it was all I could think of after seeing the title in the picture.  I’m definitely an oddball, so you’re definitely one too!

[digit]

1 hour ago, thelivingdead531 said:

I’m definitely an oddball, so you’re definitely one too!

Good company then.

 

Leaving candy on a stick behind for a moment and back to the original question--

 

It would seem to me the only way of getting any approximation of the number of molts to get from the wee tiny one to the larger one pictured would be a really in depth analysis of our only tangible clue to this mystery--the molts themselves. I have no idea of the difficulties involved but I would think that if you had access to a locality where this species was quite common (something like the Wheeler Shale in the House Range in Utah for Elrathia kingii) that it might be possible to collect an abundance of molts. I know from the minimal experience I have collecting in Utah that the cheekless molts tended to outnumber the intact specimens. If you could collect a really large sample set from a site I wonder if it would be possible to accurately measure the lengths of the molts and then plot the sizes to see if the lengths grouped into distinct size ranges? It is possible that variation in food abundance between individuals might blur any signal with size differences between individuals at the same molting stage.

 

Even if it was not possible to determine distinct size classes in a large population, it still would be a great excuse to go out and collect a lot of trilobites.

 

Cheers.

 

-Ken

[ynot]

1 hour ago, digit said:

(something like the Wheeler Shale in the House Range in Utah for Elrathia kingii)

During a trip to Denver in 1999 I went to the natural history museum.

They had a display of Elrathia kingii molts that started at 1/16th inch and culminated with a perfect 3 1/2 inch complete specimen. The "steps" between sizes were around 1/16th inch. (At least I think that is about right.)

[piranha]

7 minutes ago, ynot said:

During a trip to Denver in 1999 I went to the natural history museum.

They had a display of Elrathia kingii molts that started at 1/16th inch and culminated with a perfect 3 1/2 inch complete specimen. The "steps" between sizes were around 1/16th inch. (At least I think that is about right.)

 

 

Elrathia kingii has a maximum size around 2 inches.  A growth series in 1/16 inch increments up to ~3" was probably from another common Utah trilobite: Asaphiscus wheeleri

[Walt]

3 hours ago, digit said:

Good company then.

 

Leaving candy on a stick behind for a moment and back to the original question--

 

It would seem to me the only way of getting any approximation of the number of molts to get from the wee tiny one to the larger one pictured would be a really in depth analysis of our only tangible clue to this mystery--the molts themselves. I have no idea of the difficulties involved but I would think that if you had access to a locality where this species was quite common (something like the Wheeler Shale in the House Range in Utah for Elrathia kingii) that it might be possible to collect an abundance of molts. I know from the minimal experience I have collecting in Utah that the cheekless molts tended to outnumber the intact specimens. If you could collect a really large sample set from a site I wonder if it would be possible to accurately measure the lengths of the molts and then plot the sizes to see if the lengths grouped into distinct size ranges? It is possible that variation in food abundance between individuals might blur any signal with size differences between individuals at the same molting stage.

 

Even if it was not possible to determine distinct size classes in a large population, it still would be a great excuse to go out and collect a lot of trilobites.

 

Cheers.

 

-Ken

I volunteer. (With generous grant funding, of course)

 

[Walt]

Does anyone know if adult molting in trilobites is tied to their mating?  I know there is some speculation, based on numerous trilos found molting at the same time in the same area, that they may have grouped together for protection during that vulnerable time.  But could it be the gather en mass because the could only mate when sans the exoskeleton?  

[Kane]

1 hour ago, Walt said:

Does anyone know if adult molting in trilobites is tied to their mating?  I know there is some speculation, based on numerous trilos found molting at the same time in the same area, that they may have grouped together for protection during that vulnerable time.  But could it be the gather en mass because the could only mate when sans the exoskeleton?  

There is not even significant consensus on sexual dimorphism in trilobites given such scant evidence, let alone mating behaviours. At best (and certainly far from ideal), there are attempts to compare with modern day crustaceans and arachnomorphs, which do present (on occasion) significant morphological differences on the basis of sex. It is not that there haven't been numerous hypotheses considered, such as those I recall by Hughes and Fortey in a 2012 paper. If I recall, Richard Fortey did suggest the possibility that forms of ornamentation (horns, frills, brims, etc.) on some species of trilobite might represent sexual differences as opposed to simply being for defense, camouflage, aid movement/locomotion, etc. 

[Walt]

1 hour ago, Kane said:

There is not even significant consensus on sexual dimorphism in trilobites given such scant evidence, let alone mating behaviours. At best (and certainly far from ideal), there are attempts to compare with modern day crustaceans and arachnomorphs, which do present (on occasion) significant morphological differences on the basis of sex. It is not that there haven't been numerous hypotheses considered, such as those I recall by Hughes and Fortey in a 2012 paper. If I recall, Richard Fortey did suggest the possibility that forms of ornamentation (horns, frills, brims, etc.) on some species of trilobite might represent sexual differences as opposed to simply being for defense, camouflage, aid movement/locomotion, etc. 

I'd forgotten about that.

[Kane]

1 hour ago, Walt said:

I'd forgotten about that.

Ha! Love this image.  

[ynot]

3 hours ago, piranha said:

 

 

Elrathia kingii has a maximum size around 2 inches.  A growth series in 1/16 inch increments up to ~3" was probably from another common Utah trilobite: Asaphiscus wheeleri

Please forgive an old man and his 20 year old memory for any inaccuracies.

[piranha]

26 minutes ago, ynot said:

Please forgive an old man and his 20 year old memory for any inaccuracies.

 

 

  = my memory on a good day