Critter of the Week: Amphinome rostrata - marine bristle worm
Amphinome rostrata (Pallas, 1766), in the polychaete family Amphinomidae, can be found living amongst goose barnacles (species of Lepas) on drift objects in tropical oceans worldwide.
This large predatory species is rarely encountered in the cooler waters of New Zealand, so our polychaete expert Geoff Read was very pleased to be sent images of a specimen found near the Poor Knights Islands. This one is likely to have drifted in from the Indian Ocean, and feeds on the Lepas barnacles.
The species was first described exactly 250 years ago, and entirely in Latin (see this page at BHL), in a book by the famous German naturalist Peter Pallas. He placed his example in Linnaeus's genus Aphrodita, one of the few worm genera known at the time, and said it was collected from the "ultimo Orientis Oceano" or the Far East Ocean.
Understanding their distribution - how you can help
Amphinome rostrata broods its young, but nothing is known on how these juveniles disperse to reach new barnacle colonies to live on. Citizen science projects like NatureWatch NZ will be able to help here by recording observations of rare species in the wild helping us to understand their natural distribution patterns and biology. It is worth checking washed up barnacles on logs for other marine animals that might be hiding amongst them.
Other amphinomid species
There is also another amphinomid species to be found on goose neck barnacles, Hipponoe gaudichaudi Audouin & Milne Edwards, 1830. Hipponoe gaudichaudi [also seen spelt Hipponoa] is much smaller than A. rostrata and lives commensally inside the barnacle plates.
Check out some images of Amphinome rostrata and Hipponoe gaudichaudi in situ on their floating homes:
You can help to log observations of species you find in the wild with photographs at Nature watch NZ: http://naturewatch.org.nz/