Marine Biology (2+1)

Feeding biology of the muddy shore organisms

The greater availability of food materials as organic matter permits more large organisms to live on muddy shores. The dominant feeding types on mud flats are deposit feeders and suspension feeders, which is in contrast to open sand beaches, where the availability of organic matter is sparse. Deposit feeders are generally abundant as this area is abound with organic matter as well as large populations of bacteria in the sediments. Deposit feeding polychaetes include the genera such as Arenicola and Capitella. These polychaetes feed by burrowing through the mud, ingesting it and digesting out the organic matter including bacteria and passing out the undigested material through anus. Arenicola lives in a U-shaped burrow, in which one end of the burrow is permanently open shaft to the surface, called tail shaft and the other end of the burrow is filled with sediment which the worm ingests. The ingested sediment is passed out as faecal mounds in the tail shaft. Capitellids on the other hand, form no permanent tubes but move like earthworms through the surface layers of the sediment and ingesting it. Apart from these deposit feeders, the species of surface feeding terebellid polychaetes and the burrowing hemichordates are also represented here. The deposit feeding bivalves included are the species of Macoma and Scrobicularia. These bivalves are abundant in the temperate shores and they have separated siphons of very long inhalant and exhalent siphons, which extended up to the surface of the sediment. The long inhalant siphon helps the animal to suck the deposited organic matter and bring the same for ingestion.

Suspension feeders include the species such as various species of clams ( Mya arenaria, Macoma balthica), some crustaceans and variety of polychaetes. In general deposit feeders are more common in fine grained shores and suspension feeders become more abundant in coarser sediments where there is very little organic matter.

The common carnivorous animal on the muddy shores included are mainly fishes (e.g. Periophthalmus sp.), which feed when the tide is in and the birds, which feed when the tide is out. Indigenous mud flat predators include a few polychaete worms (Glycera sp.), moon snails (Natica, Polinices), nemertean worms and crabs.