tiki Ryan Photographic - Brachiopoda - Lamp shells

 

Photo Library

Chordates

Invertebrates

Phylum Brachiopoda

There are around 330 species of brachiopod and they are widely distributed in the world's oceans. However, they reach peak abundance in cold water and under low light conditions. They range in size from 1mm to 10 cm. Prior to the great Permian-Jurassic extinction 252 million years ago, lamp shells were at least as common as the bivalve molluscs. Subsequent to the disaster, both bivalves and brachiopods increased in the number of species but the bivalves did so at a much greater rate. It used to be believed that brachiopods were out-competed by the bivalves, but this view is no longer widely accepted. Indeed, in some parts of the world, brachiopods outnumber bivalves by orders of magnitude (New Zealand's Fiordland is the prime example but there are others such as Puget Sound).

Brachiopods are divided into two major subgroups; the articulata and the inarticulata (there are times when I think I belong in the latter group). The articulata, as the name suggests, have a distinct articulation between their two valves while the inarticulata do not. The inarticulata use muscles to keep their two valves (shells) in the correct orientation. This gives them more freedom of movement and allows some of them to burrow. Another difference between them is that the inarticulata usually possess a long pedicel, a stalk that keep the shell and body of the animal above the substrate. The articulate lampshells lie on their bottom valve with the top valve typically gaping open, which allows an incurrent of water. Both types possess a lophophore, a ciliated, often horseshoe-shaped, organ that provides both sustenance and gas exchange.

In both Fiji and Indonesia the inarticulate brachiopod Lingula is eaten. A recent paper determined that the brachiopod has a high protein content and low levels of heavy metals. However, most, if not all, of the articulate lamp shells are apparently distasteful to predators. A quote from Peter Ward's book On Methuselah's Trail: Living Fossils and the Great Extinctions follows. As it is quite lengthy you can click here if you want to jump to the photos.

 

My friend holds up the remains of the now thoroughly destroyed brachiopod and has derisive things to say about how little flesh there is for so large a shell. "No wonder they are almost extinct," he mumbles, and then asks me if they are any good to eat."Don't do it!" I tell him. My friend assures me that anything that comes out of Puget Sound waters is edible. "Don't do it!" I shout. He gives me his best stage sneer, the one reserved for scientists and their practical ignorance: "Too much college and not enough high school." The brachiopod, remnant of one of the great stocks of life, survivor since the early Paleozoic, disappears into his mouth and plays its part in the ongoing process of evolution. It's (sic) death surely serves some purpose, for it greatly diminishes the probability that at least one human being will ever again try to eat a brachiopod: even before the wretched creature is halfway down my friend turns green, and retches violently on the beach. I can't help myself, I roar with laughter. "One thing about college," I tell him when he regains his composure and control of his stomach. "At least they teach you not to eat brachiopods."

I am not certain about some of the identifications in my photographs - I am happy to accept suggestions. For more on brachiopods either read Peter Ward's book or check out the Wikipedia entry.

 

Liothyrella neozelandica white brachiopod

DW Liothyrella neozelandica white brachiopod Fiordland.jpg

Liothyrella neozelandica? white brachiopod, Fiordland

white brachipod

Liothyrella neozelandica, white brachiopods with significant growth of other sessile organisms growing on their valves, Fiordland

Magasella sanguinea

Magasella sanguinea

Magasella sanguinea, Fiordland, New Zealand

Magasella sanguinea

The main brachiopod is Magasella sanguinea but there are three other brachiopod species in the photo - this could be a world first ...

Massed brachiopods

Neothyris lenticularis

Massed brachiopods, Fiordland, New Zealand

Neothyris lenticularis

Neothyris lenticularis

Neothyris lenticularis, Fiordland, New Zealand

Invertebrates

Home

Contact Paddy

 

Ryan Photographic, Phone 303-919-7145