Paleoecology

Antipredation system

Some brachiopods of the group Mickwitziidae, had undoubtedly found the means of moving away from the bothersome parasites.Using a multitude of small pores or punctae in its shell, the animal ejected a chemical, thus getting rid of its attacker.

Feeding

Histo-enzymologic studies had proved that brachiopods are omnivorous.

These suspensivorous filterers pump water with their gills (lophophores) to filter it and to thus recover the planktonic micro-organisms (diatoms, Foraminifera, spicules of sponges, larvae of molluscs and Echinodermata, silks of worms...) for food.

But how does it works in practical terms? Powerful muscles open the shell and let penetrate the water on the two sides, carried into the shell by the beat of the gills. The food, edible particles or not, are collected by the frontal gills of the coat. A mucus secretion, emitted by the tentacles, makes it possible to bind the fragments of food to finally direct them towards the mouth. From time to time the nonedible particles are rejected by the animal.

Commensalism et parasitism...

No, the tuft on the external edge of this shell does not belong to the Terebratula. It is algae and bryozoans which had elected to reside there. Like other epibenthic and sessile forms of life, the shells of brachiopods are often encrusted with others suspensivores, which benefit thus from their hosts, without damaging them. However, there are a few true parasitic ones which attack, some trematodes, Protozoa, gastropods....

Perforation undoubtedly due to a polychaete worm
Burrows of polychaete worms on an Obovothyris shell
Tiny sponge on the brachial valve of Ferrythyris.

Food chain

Whereas the brachiopods are microphagous and live on zooplankton, in their turn they are devoured by fish,

reptiles, gastropods and crustaceans...

Present environment

The current-day brachiopods live in almost all the marine environments, which shows a certain adaptability.The inarticulated forms are particularly littoral organisms. Articulated forms occupy, either cold and deep water (Rhynchonellacae), or swallow, more or less warm water. With regard to their fossil ancestors, they also occupied very diversified ecological niches, even if the majority of them lived in fairly shallow water. The survival of brachiopods is closely related to the salinity of water, the nature of their food and of the substrate.They tolerate variations in environmental conditions with difficulty. An exception nevertheless, Lingules, with approximately fifteen species and the much studied Lingula anatina (Lamarck), live close to the coast and in brackish water.

Living alone or...

Many species lived or are still living in colonies.

A "small colony" of recent Terebratulida
Recent Terebratulida accuring in clusters
Epithyris, a middle Jurassic genus

But there are also examples of solitary brachiopods,

such as
.
Terebrirostra, a genus found in the Cretaceous chalks
Terebratalia transversa (Sow.) is a solitary animal, living attached undersides of rocks in intertidale or subtidale zones along the American coasts.

Small waterworld

Porifera (sponges) were locally very abundant and sometimes built reef-like edifices. Moeschia, Argovithyris, Lacunosella.. are articulated brachiopods who lived, together with ammonites and other mollusca, between the Oxfordian sponges. But beside this macrofauna,also existed a somewhat ignored microfauna : Thecideidae, Craniidae...

Rioultina virdunensis (Buv. 1852), a millimetric triangular form, belonged to the species which colonized sponge skeletons (dead or alive), shells of ammonites.... Moreover, in this marine biotope any dead solid support was systematically encrusted by mixed settlements.This fact played an significant role in the erecting of Porifera bioconstructions. Generally, the process taked place in two phases. First, the larvae of the encrusting organisms (annulida, bryzoa...) occupied the free places. Then, once settled and adult, these organisms was in their turn used as a support for other creatures, such as the tiny thecidean brachiopoda Rioultina.

With a little help...

(Gaillard, C., 1983)

Rioultina, serpula and other "encrusters"

Together for best and worst...

... the articulate species Hebertella occidentalis (Hall) had to carry its inarticulate "cousine" Petrocrania scabiosa (Hall). This brachiopode better likes living on the back of its Ordovician host, post mortem or still alive this is the question ?

Glossary

Epibenthic : sedentary organisms living on the sea-bed .

Sessile : animals living fixed to the substratum.

Zooplankton : small marine animals, kept in suspension by water movements and dispersed more by those movements thanby their own activities.
Serpula : segmented worm, polychaete
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