Modern Forms

Although highly abundant in the fossil record, brachiopods have been in decline since the end-Permian mass extinction 250 million years ago.  Today, there are less than 350 extant species of brachiopod in total, comprising about 100 genera.  Extant brachiopods still range throughout a variety of depths, though they are more likely to be found in cold waters between 100 and 200 metres deep.  There is quite a high abundance of brachiopods off the coasts of Great Britain; as many as 21 species.  Amongst the most well known modern forms of brachiopod is the inarticulate Lingula (subphylum Linguliformea).  A photograph of living Lingula can be seen below.

Lingula anatina
Lingula anatina, a living inarticulate brahiopod, from Australia.  Image from opencage.info.

Lingula  has been present in an almost unchanged form since first appearing in the Cambrian period around 500 million years ago.  Once found in more widespread environments, today's Lingula are confined to brackish intertidal habitats, where they live in burrows in the sand (as demonstrated in the reconstruction of the extinct Linguliform Baroisella, on the inarticulate brachiopod homepage).  One theory as to why Lingula has persisted for so long without change is that it has adapted to a habitat with few competitors.  No other brachiopods have ever managed to adapt to an infaunal (within the sediment) lifestyle.  Lingula is the only brachiopod eaten by people.  In Asia, the pedicle of this animal, which can clearly be seen from the picture above, is considered a delicacy.

Of the subphylum Craniiformea, only three genera survive today, the most common being Crania.  Crania, like all members of its subphylum, lacks a pedicle valve, and is found encrusted on hard substrates.  The Craniiformes were never a very abundant group of brachiopods.


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Characters and Anatomy
Major Subgroups
The Fossil Record
Literature and Weblinks

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