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The Zoobenthos
  • Infauna
    • live within the sediment, mostly soft bottom; 
    • mostly clams and worms (polychaetes) 
    • borrow tubes for food scavenging and oxygen supply

  • Epifauna
    • live on top of sediment, soft bottom or rocks, attached or free
    • about 80% of larger zoobenthos; hard bottoms more diverse
    • prominent examples: corals, mussels, starfish, seaearchin, sponges, barnacles

  • Epibenthos or demersal animals: live in association with seafloor but temporarily swim up into the water (prawns, shrimp, cod)

  • Size classes of zoobenthos:
    • Macrofauna (also macrobenthos): animals retained by 1.0 mm sieve; largest animals such as starfish, mussels, corals, sponges
    • Meiofauna (also meiobenthos): animals 0.1 to 1.0 mm in size, often 0.45 to 1.0 mm (depending on textbook); small animals commonly found in sand or mud, e.g. small molluscs, worms, copepods
    • Microfauna (also microbenthos): smaller than 0.45 mm; mostly protozoa (ciliates, thecate amoeba, foraminifera)
  • The interstitial community: „Sandlückensystem“, explored by Adolf Remane (Kiel, Germany). Animals that live within the water canals between the sand grains; 
    • mostly microfauna; small body size to „fit into canals“
    • long and slim bodies, length-to-width ratio up to 100:1 (normal 3-10:1)
    • flexible bodies because the interstitial room barely provide streight canals
    • organs to attach temporarily to sand grains to avoid being washed out 
    • often ciliated body surface
    • special forms occur here, such as single-individual Bryozoa, which normally only occur as colonial forms
    • some only recently discovered phyla only occur in the interstitium

  • For some nice photographs of meiobenthos click here