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, 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.
Return to Inarticulate Brachiopod Homepage
Characters and Anatomy
Major Subgroups
The Fossil Record
Literature and Weblinks
Return to Fossil Groups Homepage
