Brachiopods
Brachiopods are one of the oldest lifeforms in today’s oceans. The first brachiopods lived in the oceans of the Cambrian Period. They were plentiful all during the Paleozoic Era. Take a look at the spindle chart on the right. This chart shows how brachiopods have fared through the ages as a group. The width of the chart represents the sheer numbers and the diversity of species. You can see that the numbers of brachiopods declined sharply in the great extinction at the end of the Permian Period . They have never returned to the dominance of the Paleozoic. The hayday for brachiopods was the Devonian Period. Today there are about 300 living kinds of brachiopods that belong to 3 orders. They are:
The Lingulata
The Rhynchonellida
The Terebratulida.
Even though they are fairly common they are rarely seen because these animals inhabit very deep ocean regions.
Brachiopods live on the ocean floor and are filter feeders. That means they eat tiny bits of organic matter that float by. They have a special organ that takes in sea water and collects plankton.
Many brachiopods have a fleshy appendage called a pedicle. They use the pedicle to anchor themselves to the sea floor.
At first glance you might think you were looking at a kind of mollusk. Clams and other bivalves share some characteristics with brachiopods but the truth is they are not closely related. Brachiopods belong to the phylum Lophophorata and are related to bryozoans. They can be divided into two groups: articulate, and inarticulate. Articulate (Articulata ) brachiopods have a hinge that connects the two shell together. The inarticulate (Inarticulata ) variety hold their shells together with muscles.
Brachiopods are common fossils especially from Paleozoic Era rock layers. The Devonian Period saw the most diversity in brachiopod species.
