I am wondering why we call corals animals? According to http://www.dictionary.com - www.dictionary.com  an animal is defined as.

1. A multicellular organism of the kingdom Animalia, differing from plants in certain typical characteristics such as capacity for locomotion, nonphotosynthetic metabolism, pronounced response to stimuli, restricted growth, and fixed bodily structure.
2. An animal organism other than a human, especially a mammal.
3. A person who behaves in a bestial or brutish manner.
4. A human considered with respect to his or her physical, as opposed to spiritual, nature.
5. A person having a specified aptitude or set of interests: �that rarest of musical animals, an instrumentalist who is as comfortable on a podium with a stick as he is playing his instrument� (Lon Tuck).

Corals as far as I know do not have any form of locomotion especially SPS and LPS. Some soft corals can move by them selfs. Corals are also almost all photosynthetic. Corals also for the most part do not have a restricted growth or fixed body structure. This rules them out of the animal category completely.

Anemones are the closest to animals because they can move, have a restricted growth, and fixed structure. But they are still photosynthetic making them not animals.

Corals are also almost all photosynthetic.

No coral that I know of is photosynthetic.  The algae that lives inside their tissue is photosynthetic though...  But, I agree, corals are a strange animal indeed.

If you take away the light they will die. They can not live without light. The algae that live inside of them is part of them. To say it it a symbolic relationship is just non since. Thats like saying that we have a symbolic relationship with are white blood cells. Without are white blood cells we would get sick and die.

So with that in mind they are photosynthetic.

Besides even if they are not photosynthetic they still have no form of locomotion, they keep growing, and they do not have any set shape.

We should call them plants because plants have no form of locomotion, they keep growing, they do not have any set shape, and they are photosynthetic.

Chris- some very good questions.  Not many people actually ask these types of questions.

Corals are not photosynthetic.  Take away the light and lots of them live just fine.  In the hobby we tend to focus on the photosynthetic corals.   

They do have determinant growth, with a defined shape.  The problem is you just aren't seeing it.  Thing of an acropora head.  It is made of hundreds (and thousands) of individual little coral polyps, each its own living animal.  Looking at an acropora head is like looking at a field of snails, a ship hull covered in barnacles, a crowd of people at the delta center.  They can live as a community but each is a seperate animal.

Trust me, a coral is most definately an animal.  I'm sure you would agree that a jellyfish is an animal and that is basically a swimming coral.

Adam

Why are they animals?

Because when they spawn the eggs and sperm create a zygote (fertilized egg). Zygotes develop into a oval planula larval that hatches and swims. Planula larval is defiantly an animal. It can swim (locomotion), has restricted growth (does not grow much if any), has fixed body shape, and is non photosynthetic. Planula larval will settle down on a solid surface and then metamorphose into a polyp. Once one polyp is established it will continue to grow (LPS, softies) or asexually reproduce into more polyps (SPS).

Something I was not thinking about before was that a coral is a colony of polyps. Polyps are restricted to growth, and do have a fixed shape. The colony itself is not restricted in size or shape.

In summery corals are only animals because of how they start out in life. otherwise they would not be an animal.

Please correct me if I am wrong about this in any way.

Chris- you are almost right on the money here. 

But there is one more thing, that really is the true answer in terms of symantics.  Why are they animals? Because they evolved from animal ancestors.  That really is it.  An animal cell is going to give birth to another animal cell, and it won't ever turn into a plant.  Animal cells (including corals) have mitochondria and plants don't.  Plants have firm cell walls, animal cells are like a bag of jello with soft flexible membranes. 

Hard to explain but since I absolutely love this type of conversation I'm trying.

Adam

To say it it a symbolic relationship is just non since.

Why is it nonsense?  Is that corn field across the street part of you?  Without photosynthesis you would most certainly not exist.  Just 'cause some corals keep their farms inside their bodies doesn't mean they're plants.

In summery corals are only animals because of how they start out in life. otherwise they would not be an animal.

No.

A multicellular organism of the kingdom Animalia, differing from plants in certain typical characteristics such as capacity for locomotion, nonphotosynthetic metabolism, pronounced response to stimuli, restricted growth, and fixed bodily structure.

They are in the kingdom Animalia.  Some exhibit locomotion, some don't.  They are all nonphotosynthetic, they respond to stimuli, they show restricted growth and have a fixed body structure.  Maybe that definition isn't right

 Words!

We have to be carefull not to be blinded by symantics and dated lexical definitions. IMO we should try to craft our language around our world, not the other way around

Kingdoms of nature that we learned about in little school do not exist. Nature just isn't aranged in a hirearchy.

 Like Adam said, the way to define animals (or any critter/group of critters) that is most reflective of our reality is common ancestry. Here's how animals relate to other critters.

http://tolweb.org/tree?group=Eukaryotes - http://tolweb.org/tree?group=Eukaryotes

And here's how animals are related to each other:

http://tolweb.org/tree?group=Animals&contgroup=Eukaryotes - http://tolweb.org/tree?group=Animals&contgroup=Eukaryote s

This a cool website that is continously updated as new phylogenetic info is created.

btw, plants have mitochondria too.

dnellans wrote:   However i do not know if there is something called an animal that actually has chloroplasts as part of its own cell dna.  can anyone name one?

Maybe not yet, but there will be... Evolution is too slow so humans will speed the process up a little ;)

So the algae inside the coral does not have the same DNA as the coral does. This means it is a symbolic relationship.

So how does the coral get the algae when it changes from the Planula larval to the polyp?

Am glad that there is so many smart people on this board to help out on a subject like this. I am learning so much from this post.

It is a mutualistic sybiosis because the zooxanthallae and coral help each other. You have ancient sybionts in most cells of your body too, with their own DNA and everything.

Coral can either get their first zooxanthalae from eating it:

http://www.biolbull.org/cgi/content/abstract/196/1/70?maxtoshow=&HITS=&hits=&RESULTFORMAT=&fulltext=zooxanthellae+planulae&andorexactfulltext=and&searchid=1125797406707_41&stored_search=&FIRSTINDEX=0&resourcetype=1 - http://www.biolbull.org/cgi/content/abstract/196/1/70?maxtos how=&HITS=&hits=&RESULTFORMAT=&fulltext=zoox anthellae+planulae&andorexactfulltext=and&searchid=1 125797406707_41&stored_search=&FIRSTINDEX=0&reso urcetype=1

Or zooxanthallae can be implanted directly into the egg before fertilization:

http://www.biolbull.org/cgi/content/abstract/205/1/66?maxtoshow=&HITS=&hits=&RESULTFORMAT=&fulltext=zooxanthellae+planulae&andorexactfulltext=and&searchid=1125797406707_41&stored_search=&FIRSTINDEX=0&resourcetype=1 - http://www.biolbull.org/cgi/content/abstract/205/1/66?maxtos how=&HITS=&hits=&RESULTFORMAT=&fulltext=zoox anthellae+planulae&andorexactfulltext=and&searchid=1 125797406707_41&stored_search=&FIRSTINDEX=0&reso urcetype=1

The non-fishy People come over all the time and see my tank and ask "are Corals Plants or Animals?" and I answer, "both and neither", they are coral.

My understanding was that Corals were a class of their own because they were both Photosynthetic and they eat (and sometimes move), making them a class separate from either category.

To be honest, I can't remember where I heard this as a young child, but I always grew up believing their was 3 kinds of (multi-celled) life on the planet: Animal, Plant, and Coral.

Classification of Acropora sp.

Kingdom - Animalia (includes all animals)

Phylum - Cnidaria (includes all cnidarians - ie jelly fish, anemones, corals, hydras etc..)

Class - Anthozoa (includes all corals and anemones)

Order - Scleractinia (includes all stony corals)

Family - Acroporidae

Genus - Acropora

Species (ie palmata)

My thoughts, and you don't even need to pay me a penny!

1.  Corals are not photosynthetic.  No matter how you twist it they are not.

2.  Most corals are motile for part of their lives.  Just like a fish (or even better a jellyfish). 

3.  CORALS ARE ANIMALS.   NOT PLANTS.  Although they do have some plant like properties, so do worms!

Chris wrote: Deedo where do you get your info? How do you search for stuff like that? Also isn't your avatar a picture of a coral larval?

I like http://highwire.stanford.edu/ - http://highwire.stanford.edu/  for searching scientific literature. Many very beautifull papers about cnidarian biology are published in the Biological bulletin. This journal is also free . If you find a paper you really want to read that isn't free you can always go to the health science library at the U.

The picture in my avatar is a 20 hour old zebrafish.

The classical taxinomic hirearchy is dead. It has been shot down by science. --> there really is no such thing as a kingdom except in our wonderfull minds.

Here's a decent modern phylogeny:

Here's a better one:

You can see it is really very unnatural to force nature into a BS Linnean hirearchy and I cannot wait untill it is no longer taught in schools or used commonly. (steps off soapbox.)

Do we know how and why? Is there a reason it went this way? Is there a purpose for all of this? What is that purpose? Are we sure it happened along a time line, a heirarchy, or is each organism's existence in space and time, it's own separate entity, like a colony of coral polyps; a crowd of people; moment connected to moment. Are we sure that time marches on or is each moment of each organism separated only by it's relationship to all moments and all organisms? Is there food for thought or is it actually thought for food? Which came first, the chicken or the egg? Can it be that eggs are actually chickens in a more pure form of matter or is it the other way round? Is there really a circle of life? Once a circle is drawn, who knows the point at which it started? Who cares? How could one know the end from the beginning? Who knows the answers to these questions which are silly and yet serious too?

A'right. I'll play .

1. No, but lots of really smart people are trying hard to figure it out.

2. No, random chance.

3. No, random chance.

4. see #4.

5. Life is generated by decent with modification from an hypothesized last universal common ancestor of all life. We are sure that time never moves backwards and the generations get stranger, more fantastic, and more diverse.

6. there is both.

7. neither, it was dinosaurs maaan!

8. I don't think pure forms of matter exist in nature. It's all mixed up and stuck together maaan!

9. probably more like a web.

10. If it's drawn perfectly, only the artist. If not, you can tell by the smudge.

11. About phylogeny? I do, one of my favorite subjects. Very stimulating to think of natural history and the primitive earth and my temporal relationship to other life and my ancient ancestors.

12. I suppose the end of time is the present. it's always happening. The begginning is the hard part to know, but that makes it interesting.

13. I tried to answer them, but a few were pretty confusing

Sorry, I don't want to make it seem like I know all the answers. I'm really just a bit of a smart***

I think I agree with Deedo on everything, except I love the hierarchy breakdown.  I still think it works well and I'm glad we have it.  Although maybe I'm agreeing with you here after all.  I just think the breakdown and divisions should be made along the lines of the two graphics you posted.  Which I think is what you are saying.  Anyway I at least agree with everything else.

But classification of items based upon derived characteristics is awesome.  I can't imagine not having it.

Adam

Deedo, from time to time, I bust my gut laughing  at something on this MB. Your post was one of those. I never thought my serious rambling would result in something so funny. Thanks for giving me a healthy laugh. 

You might have guessed this but I believe that outside of this temporal existence we live in, time does not exist, at least not in the way we know it. I also believe there is purpose to life, not just random chance. Life appears to be complex, as you said, "stranger, more fantastic, and more diverse".  I believe that random chance would lead to degradation and less complexity, not more.

I know it's a personal failing but I have an argumentative streak :) And it's all in good fun right? I'll stay away from the existential metaphysics though, that is a very personal thing and not for argument, like broccoli :)

Randomness is not the key to evolution but rather high diversity and mutations.

But since these mutations are entirely random (unless you believe in Lamark) evolution is enabled by random proccesses. The fact that the selective pressures which shape evolution are not random does not remove this stochastic baseline. Put another way, there are infinite number of theoretical ways to survive in any niche, which ones are taken is left to chance. The same niche can be ruled with elegance or brutality.

Mutations are not, in any sense, major deviations from the parent organism or physically monstrosities.

As far as I know, the jury is still out on this one. The microevolution that we easily can see within our lifespans is indeed a process of small accumulating changes, however, we are unable to rule out the possibility of evolutionary 'leaps.' An exampe of a leap may be found in bony fish. They have had a whole genome duplication millions of years ago and thus tend to have two of every gene. The fact tht bony fishes rule the waters where once there was only cartilaginous fish and eels implies that in one generation a vastly more fit fish was born. microeveolution can only explain refinement, it kinda breaks down on questions of novelty. --> macroevolution has almost certainly happened but it's rare.

According to Julian Sprung some algae are classified are plants, some protists, and yet others monera.

To say that there are five kingdoms makes an artificial value judgment. (whether there is such a thing as a natural value judgment is another debate.) We have to say what is a big enough difference to warrant a whole new kingdom. So fungi gets a kingdom when really they are very closely related to us. Untill the 90s this was always done sort of arbitrarily. Now that we can sequence genomes and examine protein structures/functions it is becoming apparent that we can't pigeonhole all life into five groups and still adequately describe the realtedness of life.

Protista is an especialy bad grouping because it likely is not monophyletic. That is, some classically defined 'protists' are actually more closely related (evolutionarily) to plants than to other classically defined protists. So... lump ' these wierd ones with plants? NO! then are only ignoring the true diversity of life.

Monera is another bad one since it actually seems to contain 2 large groups, one of which seems to be more closely related to us. That's how the logic behind a seven layered hirearchy breaks down. To actually describe life we need superkingdoms and subkingdoms and subsubkingdoms and supersuper phylums etc. It becomes an unknowable mess.

To me it's all reminescent of the story of Ptolemy and Copernicus. The dogma of both their eras was that the earth sat stationary in the center of the universe. It was taught in school and written in books by very wise men so it must be true. Ptolemy was a brilliant thinker and mathematician and he actually modelled how this would look. the model was extraordinarily complex, a real testament to his genious. Nobody but the most brilliant of people can understand it to this day.

Copernicus found no fault with Ptolemy's math. He just went like "dude, that's nuts! If we let the planets rotate around the sun the math is  much more beautifull." 

Using these man made words like kingdom, phylum etc. to describe the diversity of life is like ptolemy building his models. It is so much more beautifull, simple and true to draw a tree.

whoa, sorry 'bout the rant everyone . I think I might feel a little too strongly about this. Time to go sit in front of the tank .

SandRider wrote: .....Evolution is a process that does occur but the timelines and to what extent is obviously very controversial and questionable.

Not sure how this conversation merged into a discussion of evolution, but for a bunch of science nerds, you are all sure behind on your reading:

http://www.darwinismrefuted.com/20questions01.html - http://www.darwinismrefuted.com/20questions01.html

Darwin's theory of evolution has been disproved as impossible by modern science. The problem is that when they tried to 'update' high school science classes with this new information, there was an uproar from athiests stating that teaching that evolution is impossible is preaching religion (creationism as they call it) in classrooms.

Quite an interesting little political battle to follow. We are essentially being stopped from teaching current science findings least it prove the existance of God.

Apparently Oklahoma was able to win the battle, so we'll probable hear more noise about this as is spreads across the country:

http://www.simonyi.ox.ac.uk/dawkins/WorldOfDawkins-archive/Catalano/education/oklahoma.shtml - http://www.simonyi.ox.ac.uk/dawkins/WorldOfDawkins-archive/C atalano/education/oklahoma.shtml

http://www.science-spirit.org/archive_cm_detail.php?new_id=261 - http://www.science-spirit.org/archive_cm_detail.php?new_id=2 61

improdigal wrote: ...The problem is that when they tried to 'update' high school science classes with this new information, there was an uproar from atheists stating that teaching that evolution is impossible is preaching religion (creationism as they call it) in classrooms.

What percentage of this Country is Atheist?  It seems that we are moving from pleasing the majority to pleasing the minorities...Or the loudest (squeaky wheel gets the grease).

Summertop wrote: What percentage of this Country is Atheist?  It seems that we are moving from pleasing the majority to pleasing the minorities...Or the loudest (squeaky wheel gets the grease).

15% at last poll (atheist or agnostic)

More important from my point of view is that people seem to be forgetting that this country was setup to be tolerant of all beliefs. Instead they are moving toward being Intolerant of ALL Beliefs (so that we don't offend those that believe differently).

The idea was for everyone to act like grown-ups and let people think what they want. Little too much to ask apparently...

 I have found that arguing about evolution always ends up the same.... both sides more strongly holding to thier beliefs and a lot of hurt feelings.

From what I heard about it, Mark actually stated the results of the evolution battle above:

 I believe that random chance would lead to degradation and less complexity, not more.

What I heard was that they found the process of natural selection resulted in the simplest, not the most complex organism always winning out. ie. there wouldn't be people and animals walking around, there would be a planet of large algaes and various fungi. :-)

Deedo is totally right about that article, I honestly couldn't find a better one when I was looking yesterday. I haven't seen the 'proof' myself at all. I've only read all the politcal articles about how the school system is trying to decide what to teach now that Darwin has been disproven by modern science.  And even those articles are hard to find, because this battle stated 1-2 years ago.

Adams right though, there will always be people on both sides that won't budge. I believe most religions agree the almighty intentionally setup 2 points of view for everything, so people had to believe via faith rather than proof.

This has been quite the fun conversation though, you can actually read people biting their tongue and trying to be polite when disagreeing.

I think Chris is trying to say symbiotic realationship, not symbolic.  Symbiotic means "A close, prolonged association between two or more different organisms of different species that may, but does not necessarily, benefit each member."

http://dictionary.reference.com/search?r=2&q=symbiotic - http://dictionary.reference.com/search?r=2&q=symbiotic