By Josh Moloney
Known as Periclimenes soror until a recent taxon swap, the Seastar Shrimp Zenopontonia soror is a commensal species of shrimp with a distribution in the Indo-Pacific region, Japan and Hawaii. In Australia it has been recorded from Western Australia across the top of the continent and down the east coast to Sydney. It benefits from its association with seastars, obtaining nutrients and shelter. They come in a variety of colours often matching their host. Their markings are variable and they are often heavily speckled and occasionally have a white strip along the back.
If you carefully turn over the Mosaic Seastar Plectaster decanus here in Sydney you can sometimes find them kickin’ it on the underside, close to the centre near the mouth. They don’t seem too bothered by this making them easy to photograph if you’re macro-equipped!
Other seastars that Z. soror have been found to associate with include Choriaster granulatus (Doughboy Seastar), Culcita novaeguineae (Cushion Seastar), Acanthaster planci (Crown of Thorns Seastar), Linckia laevigata (Blue Seastar), Asteropsis carinifera (Sheriff-Badge Seastar) to name a few. If you find them associated with any seastars other than those mentioned here please take photos of both the shrimp and host and share them on our Facebook page.
Just remember to be gentle and leave them the way you found them!