page_title: Brachiopod
section_title: Feeding and excretion
hierarchical_section_title: Brachiopod / Description / Feeding and excretion
caption_attribution_description: English: Liospiriferina rostrata (Brachiopod). Brachiopods filtered plankton, using a specialized organ: the lophophore. It is exceptional to be able to find silicified skeleton of this organ, visible in this specimen. Stage&#160;: Pliensbachian (189.6 ± 1.5 Ma and 183 ± 1.5 Ma (million years ago)) Lower Jurassic. Locality&#160;: France Size: 35x30 mm Français&#160;: Liospiriferina rostrata (Brachiopode). Les brachiopodes filtraient le plancton à l’aide d’un organe spécialisé le lophophore. Il est exceptionnel de pouvoir retrouver le squelette silicifié de cet organe, visible sur ce spécimen. Etage : Pliensbachien (-189,6 ± 1,5 et -183,0 ± 1,5 millions d'années) Jurassique inférieur. Localité&#160;: France Taille: 35x30 mm
context_page_description: Brachiopods, phylum Brachiopoda, are a group of lophotrochozoan animals that have hard "valves" on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection. Two major groups are recognized, articulate and inarticulate. The word "articulate" is used to describe the tooth-and-groove features of the valve-hinge which is present in the articulate group, and absent from the inarticulate group. This is the leading diagnostic feature, by which the two main groups can be readily distinguished. Articulate brachiopods have toothed hinges and simple opening and closing muscles, while inarticulate brachiopods have untoothed hinges and a more complex system of muscles used to keep the two valves aligned. In a typical brachiopod a stalk-like pedicle projects from an opening in one of the valves near the hinges, known as the pedicle valve, keeping the animal anchored to the seabed but clear of silt that would obstruct the opening.
  The word "brachiopod" is formed from the Ancient Greek words brachion and podos.
context_section_description: The water flow enters the lophophore from the sides of the open valves and exits at the front of the animal. In lingulids the entrance and exit channels are formed by groups of chaetae that function as funnels. In other brachiopods the entry and exit channels are organized by the shape of the lophophore.  The lophophore captures food particles, especially phytoplankton (tiny photosynthetic organisms), and deliver them to the mouth via the brachial grooves along the bases of the tentacles.
  The mouth is at the base of the lophophore. Food passes through the mouth, muscular pharynx ("throat") and oesophagus ("gullet"), all of which are lined with cilia and cells that secrete mucus and digestive enzymes. The stomach wall has branched ceca ("pouches") where food is digested, mainly within the cells.
  Nutrients are transported throughout the coelom, including the mantle lobes, by cilia. The wastes produced by metabolism are broken into ammonia, which is eliminated by diffusion through the mantle and lophophore. Brachiopods have metanephridia, used by many phyla to excrete ammonia and other dissolved wastes. However, brachiopods have no sign of the podocytes, which perform the first phase of excretion in this process, and brachiopod metanephridia appear to be used only to emit sperm and ova.
  The majority of food consumed by brachiopods is digestible, with very little solid waste produced. The cilia of the lophophore can change direction to eject isolated particles of indigestible matter. If the animal encounters larger lumps of undesired matter, the cilia lining the entry channels pause and the tentacles in contact with the lumps move apart to form large gaps and then slowly use their cilia to dump the lumps onto the lining of the mantle. This has its own cilia, which wash the lumps out through the opening  between the valves. If the lophophore is clogged, the adductors snap the valves sharply, which creates a "sneeze" that clears the obstructions. In some inarticulate brachiopods the digestive tract is U-shaped and ends with an anus that eliminates solids from the front of the body wall. Other inarticulate brachiopods and all articulate brachiopods have a curved gut that ends blindly, with no anus. These animals bundle solid waste with mucus and periodically "sneeze" it out, using sharp contractions of the gut muscles.
caption: A fossil of Spiriferina rostrata with visible brachidium (lophophore support)
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