Description: This polychaete worm lives as an ectosymbiont on sponge and is extremely well camouflaged against the surface of the sponge. It is relatively small and broadly oval in shape. It is orange in colour with transverse ridges visible running across the dorsal surface body. The animal is usually flecked with lighter coloured sections which have the appearance of a lights or sparks, hence the genus name 'Spinther', which is Greek for spark.

Habitat: Lives as an ectosymbiont on sponge.

Distribution: Scattered records from around Britain and Ireland, possibly under-recorded due to cryptic nature.

Similar Species: Unlikely to be confused with any other species.

Key Identification Features:

• Distinctive oval-shaped orange worm.
• Lives on orange-coloured sponge.
• Covered in lighter patches of colour that give the appearance of sparks.
• Transverse ridges visible.

Distribution Map from NBN: Spinther oniscoides at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Spinther oniscoides at iNaturalist World Species Observations database.

GBIF data for Spinther oniscoides

WoRMS: Spinther oniscoides at World Register of Marine Species. Accepted name: Spinther oniscoides Johnson, 1845. AphiaID: 131102.

Classification: Biota; Animalia; Annelida; Polychaeta; Polychaeta incertae sedis; Spintheridae; Spinther