To coelenterate or not to coelenterate, that is the question...
Whether 'tis Nobler in the nomenclature to correlate
The Threads and Barbs of nematocysts,
With the colloblasts of the ctenophores,
And by opposing end their correlation: to declassify, to reclassify
No more; and by classify, to say we reorganize
The Heart-ache, and the thousand Natural shocks
That gelatinous bodies are heir to? 'Tis a re-classification
Devoutly to be wished. To declassify, to reclassify,
To reclassify, perchance to genetically code; aye, there's the rub,
For in that coding, what truth may come,
Comprehending these evolutionary differences,
Must give us pause. There's the respect
That makes Joy of so long life...
(with deepest apologizes to The Bard)
Science is active, it is about observing, testing, considering, and refining. With Science we learn additional information and refine our perspectives, the case of the cnidarians and the ctenophores is an excellent example; Science utilizes the method of using our best-current-facts to comprehend the world around us. Our ability to *see* the natural world around us changes greatly over time due to advancing technologies (microscopes, telescopes, genetic coding, etc.) and of course the effect of standing-on-the-shoulders-of-those-that-went-before (discovery builds on discovery, comprehension on comprehension... ).
E. Haeckel- Cnidaria |
So... what does this have to do with our coelenterate controversy?
...any excuse for a Haeckel! Ctenophora |
So, what are some of those differences which led scientists to go to the lengths of creating a whole new PHYLUM?!?
(and how the heck do you pronounce coelenterate, cnidaria (UK), and ctenophore anyway?!?)
Cnidarians (Coelenterates)
|
Ctenophores
|
|
Symmetry -body
|
Radial
|
Bi-radial
|
Digestive tract
|
Incomplete (single) digestive opening,
food enters and leaves the body through the same opening
|
Complete (one way) digestive tract
with 2 openings: oral (mouth) and anal.
|
Prey capture
|
*Stinging cells- cnidocytes/ nematocysts
|
Sticky cells- colloblasts
|
Larval form
|
Planula
|
Cydippid
|
Development
|
Diploblastic, with true tissue
|
Triploblastic
|
(by the way, any terms/words you are
uncertain of can easily be found online! I’m in a rush today! : )
*Those stinging cells are key by the way!
It appears that cnidarians are more directly in-line evolutionarily, and that the ctenophores are more of a sibling group to all other animals. Ctenophores have muscle and nervous systems that seem to have evolved independently from other modern animals (google Hox and Homeotic gene contingents!). Where the ctenophores sit in their forms and functions excluded them from being grouped in the Phylum Coelenterata.
So, you see, what some people may think of as a negative, "controversy", Science sees as normal growth and development. We start with basic information, and then, based on observation, testing, and consideration we develop and refine the information. Since our abilities and technologies improve our ability to perceive more of the natural world improves also; consider the path to what we know about genetics ...
Double Helix |
...and one of the RESULTs of all of that scientifically acquired knowledge? Modern medicine that allows targeted treatment of many genetics illnesses.
Science builds on *small* steps...
... ok, sometimes we get lucky and we get a big step, but you know what I mean...
And we *still* have a lot to learn about genetics!
This is how science is supposed to function, always improving on it's self, and how we see our world.
No comments:
Post a Comment