The Mactridae Family includes 181 species comprising 5 subfamilies (Mactrinae (25 genus), Lutrariinae (8), Tanysiphoninae (1), Resaniinae (1), Darininae (1))
and 36 genus (Mactra (51 species), Lutraria (19), Spisula (16), Mactrotoma (13), Mulinia (10), Oxyperas (9), ...)

Phylum      : Mollusca
 Class       : ⤷Bivalvia 
  Subclass    : ⤷Autobranchia 
   Infraclass  : ⤷Heteroconchia 
    Subterclass : ⤷Euheterodonta 
     Superorder  : ⤷Imparidentia 
      Order       : ⤷Venerida 
       Superfamily : ⤷Mactroidea 
        Family      : ⤷Mactridae

Common name : otter shell, trough shells or duck clams

Aspect : equivalve (two valves equal in size), inequilateral (beaks not central, shifted anteriorly), and typically elongated-oval or trapezoidal; The outline is rounded posterior and more pointed anterior; moderately inflated and thick-walled; smooth surface with concentric growth lines; color ranges from white/cream to yellowish-brown; hinge with strong cardinal teeth (usually 2 in each valve) and lateral teeth; size varies from ~3–5 cm up to 20–25 cm

Feeding : filtration of microorganisms in suspension (phytoplankton, zooplankton, detritus, and organic particles)

Environment : cosmopolitan, temperate to tropical waters; in intertidal to shallow subtidal (0–100 m) in marine coastal zones; buried in sand or muddy sand on clean, medium- to coarse-grained sands