To know some more

Lophophore

The lophophore is composed of many filaments, supported or not by a calcareous skeleton called brachidium. It ensures the breathing and the nutrition of the animal.

Internal features of Terebratula (d'after A. E. Brehm 1884)

Anatomy of a recent species

Conchyliology Book
Woodward 1870

Notosaria nigrigans (Sowerby)

Brachial apparatus (brachidium)

Spiriferina

Terebratula

Zeilleria

The attachment of the shell.

The attachment processus of the valves varies relative to the way of life of the brachiopods. Many species have a muscular foot (pedicle)

with which they are anchored on the rocks, rollers, shells..., it is the case of Terebratula s. l. This fixing can still be reinforced by a "pseudo-byssus", divided into multiple filaments. Other shells, like Craniidae, are directly cemented on the substrate by their ventral valve. On sand or mud, the brachiopods have to adapt their attachment system to the movable sediment.

In order to avoid being buried

.

- Productidae have spines,

- Spiriferidae have "fins,"

- Atrypidae have "ruffles"

As for Lingula, it lies burried in the substrate. It uses its long stalk (more 30cm) to move like a worm. Lingula is the only brachiopod that is able to leave the place where it fixed initially. The majority of the species stay definitively at the same place. They are sessile animals, except the larvae, which swim freely during several days.

Some brachiopods attached to

  • muddy sediments :

Aulacophoria, Chonetes, Dictiothyris, Digonella, Mucrospirifer, Pentamerus, Productus,netes, Dictiothyris, Digonella, Mucrospirifer, Pentamerus, Productus,

  • movable substrates :

Atrypa, Cyrtina, Parajuresania, Platystrophia, Spiriferina, Strophomena,

  • hard substrates :

Cancellothyris, Davidsonia, Goniorhynchia.

Reproduction

In almost all the brachiopods the sexes are separated and hermaphrodites are uncommon. Consequently, reproduction is mainly sexual. The reproduction period is subject to variation in temperature. Genitals are in the visceral cavity and the sinus of the mantle

Among the articulated brachiopods, one animal can lay more than 3000 eggs a day. The fertilization may be external, but mostly it is internal.

A tiny trefoil larva leaves the egg, - swims for some time freely in the water, to fix itself finally by one of its lobes. From then, the mantle begins to secrete the shell.

Among the inarticulated brachiopods, the fertilization often is external, only sometimes it is internal. The Lingulidae, for instance, already secrete their embryonic shells (protegulum) before they are born. As soon as they are born, they first adopts a pelagic way of live for a couple of weeks.They live in the plankton and grow slowly. Then it attaches itself to the substratum.

The presence of antennas

Rare genera (Cheirothyris of the Jurassic superior and Tetractinella of the Triassic...) seem to be provided with sensory appendicular bodies.

The frayed prolongations of frontal commissure (see photo below)do indeed look like antennae.

Cheirothyris

Tactile sensitivity

In the current forms, the cilia probably have a tactile function, whereas in the fossil species, such as the tubular spines fixed on the shell of Acanthothiris spinosa (Linnaeus), played this sensory role, with an aim of warning the animal.

The spiny shell of Acanthothiris spinosa (L.)

Live expectancy

Some current brachiopods may live up to 15 years.

In the aquarium

Aquarium experiences with the Craniidae prouved that these organisms can live for several months in closed environment, resistant to variations in temperature, intense sunlight, changing of salt concentration and jolts during the transport...! (Grzimek, B.1970).

Glossary

Hermaphrodite : who is equipped with the characters of the two sexes (bisexual)

Pedoncle : fleshy stalk

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