OK, I can ID either one fairly easily... but what really separates the two? How do they get scallops to be associated with octopi and not with brachiopods??? Clue me in here.
Brachiopod or Mollusk... what's the real diff?
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H2Andy
Contributor
i am so glad you asked this, because just the other day i asked myself this
same question. the differences used to classify the critter as either a bivalve or a brachiopod are as follows:
1. Brachiopods have two valves which are different when seen from the side of the animal. Seen from above, the valves are symmetrical. The bivalves have two valves which are mirror images of each other when seen from the side. Seen from above the valves are not symmetrical.
2. Brachiopods have calcareous arches supporting the brachia. The bivalves lack these.
3. Brachiopods are attached to the substrate by the muscular pedicle. Bivalves use thin threads for attachment.
4. Brachiopods have valves made of calcium carbonate or calcium phosphate. Bivalves have valves only of calcium carbonate.
There are in fact only a few living brachiopods today, from what i understand.
The bivalves basically squeezed them out of existence.
same question. the differences used to classify the critter as either a bivalve or a brachiopod are as follows:
1. Brachiopods have two valves which are different when seen from the side of the animal. Seen from above, the valves are symmetrical. The bivalves have two valves which are mirror images of each other when seen from the side. Seen from above the valves are not symmetrical.
2. Brachiopods have calcareous arches supporting the brachia. The bivalves lack these.
3. Brachiopods are attached to the substrate by the muscular pedicle. Bivalves use thin threads for attachment.
4. Brachiopods have valves made of calcium carbonate or calcium phosphate. Bivalves have valves only of calcium carbonate.
There are in fact only a few living brachiopods today, from what i understand.
The bivalves basically squeezed them out of existence.
OP
They died out with the dinosaurs... and only a few deep water specie exist now.
What, pray tell, is a brachia??? I don't think it's dem things I have holdin' up my shelves!
What, pray tell, is a brachia??? I don't think it's dem things I have holdin' up my shelves!
H2Andy
Contributor
hahaha... the root is not "brachia" but "brachio" meaning "arm" or "radial" (from the
Latin brachium) (brachia is the plural?)
and then you add "pod" to that (as in, foot, foot-like part) (from Latin podium, Greek podion) and you end up with:
arm foot-like ?????
yikes... try two
well... as far as i know, the brachiopoda are a pair of arms that have tentacles for capturing food, which gives the brachiopods their name... i've heard them described
as "brush-like arms" so i imagine two stalks with bunches of little "hairs" at the end. never seen a pic.
Latin brachium) (brachia is the plural?)
and then you add "pod" to that (as in, foot, foot-like part) (from Latin podium, Greek podion) and you end up with:
arm foot-like ?????
yikes... try two
well... as far as i know, the brachiopoda are a pair of arms that have tentacles for capturing food, which gives the brachiopods their name... i've heard them described
as "brush-like arms" so i imagine two stalks with bunches of little "hairs" at the end. never seen a pic.
mbuff
Registered
woof good question. And some good answers.
According to a couple of different sources, (Pearse, Buchenbaum, 1987 and the website below) the Brachiopods are also distinct because of their lophophores -- winglike feeding appendanges that preceed the mouth. They are considered to be deuterostomes ... organisms where the anus develops before the mouth. Molluscs are protostomes... "mouth before anus" in development. The difference in symmetry is important as well, as mentioned above.
I took my info from this website as well as my trusty ol' invert zoo book.
http://www.ucmp.berkeley.edu/phyla/lophotrochozoa.html Click on the morphology link.. that's a good page too and addresses some of the body plan differences (and gives a nice diagram...
According to a couple of different sources, (Pearse, Buchenbaum, 1987 and the website below) the Brachiopods are also distinct because of their lophophores -- winglike feeding appendanges that preceed the mouth. They are considered to be deuterostomes ... organisms where the anus develops before the mouth. Molluscs are protostomes... "mouth before anus" in development. The difference in symmetry is important as well, as mentioned above.
I took my info from this website as well as my trusty ol' invert zoo book.
http://www.ucmp.berkeley.edu/phyla/lophotrochozoa.html Click on the morphology link.. that's a good page too and addresses some of the body plan differences (and gives a nice diagram...
There are tons of brachiopod species alive today... just ask the New Zealanders. Can't get away from the dang things.
Just because they had a slump following the Paleozoic doesn't mean they're a relict group. Heck, almost EVERYTHING had a slump at this time. Brachiopods are doing just fine and dandy in cooler, deeper waters, especially in the southern hemisphere where american media and bad science fears to tread. They've actually done quite a bit of speciation following the Cretaceous, putting them on the ecological upswing the last 60+ million years.
Heck, all the specimens in my lab are pickled. I have to bring in a fossil from HOME to show students!
Just because they had a slump following the Paleozoic doesn't mean they're a relict group. Heck, almost EVERYTHING had a slump at this time. Brachiopods are doing just fine and dandy in cooler, deeper waters, especially in the southern hemisphere where american media and bad science fears to tread. They've actually done quite a bit of speciation following the Cretaceous, putting them on the ecological upswing the last 60+ million years.
Heck, all the specimens in my lab are pickled. I have to bring in a fossil from HOME to show students!
H2Andy
Contributor
archman:
see, that's my problem. not a single New Zealander around
when i need my questions answered.
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