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Characters and anatomy

    Ostracods are small crustaceans, their size ranges from about 0.05 - 2mm long and inhabit a wide range of habitats, they are mainly found in freshwater, marine and brackish environments. Ostracods are mainly found living on the sea floor (benthic), although some are found floating in surface waters (planktonic). Diagram 1 at the bottom of the page shows a diagram of an ostracod.
   
    A distingishing feature that ostracods have is a bi-valved calcified carapace which is hinged at the upper margin (often found fossilized), which encloses the soft bodied parts. Adductor muscles are attached to this carapace and are used to open and close it. They have apendages which can drop out and can use for walking, swimming, reproduction or feeding.
   
    The soft bodied parts can be divided into two main parts the head (cephalon) separted by the thorax (between the head and abdomen) by a slight constriction.
 
   
They can reproduce both sexually and asexually and display sexual diamorphism, the male and females carapaces are differnt shapes.

Photograph of a female Leptocythere lacertosa
Photograph 1. of a female Leptocythere lacertosa. Taken from Recent British Intertidal Ostracoda. Photograph of a male Leptocythere lacertosa
Photograph 2. Of a male Leptocythere lacertosa. It is clear to see that compared to the female it is more elongate. Taken from Recent British Intertidal Ostracoda.    
   
    They grow like other crustaceans by moulting (ecdysis). They have 9 moult stages and by the 9th moult stage they are an adult.
One way ostracods can be divided is based on the features of their carapace.  Pelagic forms tend to have a smooth carapace and may have long powerful swimming appendages. Benthic ostracods can burrow into the substrate, so tend to have carapaces that are smooth, robust and occassionaly elongate.

    They display a range of eating habits being scavengers, filter-feeders, detritivores or herbivors.


A sketch of the interior and exterior of an ostracod carapace, both of a left valve. Permission sought from UCL
Diagram 1, displays a sketch of the interior and exterior
of an ostracod carapce, both of a left valve.
Permission sought from UCL.