Tuesday, November 12, 2013

Because Brachiopods-that's why! 5 Things to know about Brachiopods!

Boreadortis recula aequivalvata Öpik
Image by Open Up!
What are Brachiopods?  
Brachiopods are actually a PHYLUM of animals. That's right a whole GROUP of animals that most folks have probably never heard of!
Brachiopod, Mucrospirifer thedfordensis,  Fossil No. F-202
image by Herman Giethoom
Brachiopods are a very old, old group of invertebrates with a relatively rich fossil record.  They have two shells (and are superficially similar to bivalves, e.g; clams and mussels) but are better known in several other ways...

Brachiopods are one of the few groups of marine animals which live ONLY in the Ocean! (Echinoderms being one of the others...)

Some places you learn about some new mammal, but HERE at the Echinoblog? you learn about a whole PHYLUM of animals in five easy steps!

1. What does the name mean? 
Brachiopoda, when you break it down:  "brachio"= arm and "poda"= foot. Wha?  The Arm foot?

The name refers to a structure known as the pedicle. That's the purple stalk bit that is anchoring the animal down to the substrate. This is how the pedicle looks
in the group informally known as the "articulate" brachiopods. Arm refers to the muscular arm-like aspect and "foot" to its use (or disuse) in attatching to the bottoms.

The pedicle manifests in two different ways relative to which of the two major groups of brachiopods you are looking at!

One group has been referred to as the "Articulate" brachiopods. And yes; they are very well spoken thank you. ha ha.you have now caught up with the jokes:

The "articulate" part refers to how the two shells have teeth that articulate with one another.. Here are some hinges on various brachiopod valves.. (images below by Open Up! fr. this awesome photoset fr. the University of Tartu-go take a look at some AWESOME photos! )
Ladogiella imbricata Öpik  Clinambon anomalus praecendens Öpik
Boreadortis crassa Öpik, 1934Ilmarinia sinuata (Pahlen, 1877)

In the "inarticulate" brachiopods the pedicle is this much more developed tail-like feature. the animal is almost kind of a worm. These live in burrows. People eat these! (see below)
亞氏海豆芽 Lingula adamsi Dall
Lingula adamsi Dall by Changhua Coast Conservation Action
2. So these look like clams? What's the diff? 
Relative to the animal inside, brachiopod shells are oriented top-bottom vs. those in bivalves, which are oriented left-right
This image from Kristie Bradford's Historical Geology web page!
Yes. I know the symmetry seems strange and can be oddly difficult to "get" the first time around. Here are some brachiopods...
425,000,000 Years Old Today !
image by mpjones_007

Coptothyris adamsi3a
Image by Alexander Semenov
and here's some clam for comparison (positioned for convenience!)
Two Halves are Better than One
Image by Royston Vasey

3. What/How do they eat?
Brachiopods have a feathery feeding structure called a lophophore! Brachiopods are basicaly suspension feeders. Water flows in and over the lophophore and tiny finger-like bits called cilia pick the food up!

Here's some reality from the very talented Arthur Anker showing the lophophore with the animal's valves open!
Deep-water brachiopod

A further GREAT pic of the lophophore can be found here..

And here is the diagrammatic approach that gives you a general idea of what you're looking at.... The animal below has been turned upside down to show parallel orientation with the pic above...

4. In the Paleozoic (roughly 250-500 million years ago), brachiopods were once THE happening invertebrate! 
Brachiopod Slab
image by David Cartier
Earliest known fossils date back to the Cambrian (600 million years ago-but probably more), but the time of the brachiopod was in the Paleozoic!  (bear in mind how vast a time period 250 million years is.. that's MUCH older than humanity..).  They dominated in diversity and abundance. This was their "time"...   Sadly, most brachiopods underwent a huge extinction at the end of the Paleozoic...

According to the World Brachiopod Database only about 385 species occur today from the ~30,000 described (mostly fossil) ones!!

Many of these species live in out of the way and isolated places...

Here is a gorgeous pic of Coptothyris adamsia from the Sea of Japan
Coptothyris adamsi3a
Image by Alexander Semenov
Here is Laqueus californica from Monterey Bay in some pretty amazingly high densities...

and more from Alexander Semenov: Hemithyris psittacea (Rhynchonella psittacea)
Brachiopod pair

5. Geology! Fossil Brachiopod Shells are sometimes replaced by Pyrite! (aka Fool's Gold)
In the fossil record, the "shells" (called valves) of brachiopods sometimes undergo a process in which they are replaced with pyrite aka fool's gold!

This makes them golden and sparkly!
Pyritized shell pavement, Middle Devonian Silica Shale, Sylvania, Ohio, USA
Image by jsj1771
Fossils and Pyrite 2
Image by E. Sese
Pyritized Paraspirifer bownockeri, Silica Fm, Middle Devonian, Lucas Co, Ohio, USA
Image by JS1771

5a! More Geology Fun! Brachiopod valves are often found in cross sections of rock! 
Geologists know the value of a good cross section! Brachiopods are VERY abundant in Paleozoic rock. And if you cut through the shells of one you get some pretty distinctive impressions in the rock..
Brachiopods Of #4 Kildare St. (With Guinness-Tinted Fingernail For Scale)
Image by Maitri

Sometimes there are minerals such as agate!
Agatized fossil clams (brachiopods) found in some South Dakota decorative rock
Image by Captain Tenneal

Brachiopod shells can be pretty dense and sometimes you see a lot of them! 
Sometimes you see some neat rare stuff.. like this soft-part preservation of a lophophore!
Brachiopod fossil with preserved lophophore
Image by Dietmar Down Under

FUN FACT!  People EAT brachiopods!
I wrote about this earlier... but yes, apparently some curry and/or garlic is appropriate....
Lingulids, Thai market
Image by Peter Roopnarine


octopod said...

JFC, man, is that the lophophore preserved in the agatized specimens? Wow...

ChrisM said...

This one actually shows a really nicely preserved spirifera. It seemed too complicated to show it relative to the lophophore.. http://www.flickr.com/photos/56837663@N03/9362574328/in/photolist-fgkDaj-9FmFXV-grSJZv-duuAe3-a7bSgQ-8FD19D

Artful Nature said...

I have fossil brachiopods interesting,brings them to life. thanks

Anonymous said...

very interesting I have a jar of fossil brachiopods some I found here in Florida, this brings them to life. thanks

myomin hlaing said...

Best for knowledge share and want more in other aquatic life. Thank you