Biodiversity #23 – Feather stars

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Biodiversity #23 – Feather stars are a type of crinoid, a word derived from the Greek meaning roughly ‘lily’ and ‘form’.

Featherstar

Like starfish – or more correctly sea stars – the feather star is a echinoderm. They are marine animals characterised by a mouth on top surrounded by feeding arms.  Compare the sea star which has a mouth on the bottom surrounded by feeding arms.  Like sea stars they display pentaradial symmetry (i.e., 5 planes of symmetry – down the centre of each arm). Primitive feather stars had just five arms, in modern feather stars these arms have branched into larger numbers. They have been around since the Ordovician period i.e., about 450,000,000 years! There are currently around 600 species and the majority are able to swim freely. (And I bet you thought they were plants – I did!) Here’s a video of a feather star feeding taken at Australia’s Christmas Island.