Idanthyrsus pennatus   (Peters,  1855) (Marine Worm)
Organism information awaits expert curation
Class: Polychaeta

Size: 27mm by 4mm

Colour: Nuchal hooks, coppery red.

Prostomium covered by two large opercular stalks bearing modified setae in two rows. The paleae of outer opercular series with strongly curved plume-like shaft. Inner paleae slightly curved, pointed, plain. Three parathoracic setigers with oar-shaped setae and fine twisted setae with teeth along its distal end on the dorsal rami and on the ventral rami oar-shaped setae and fine, serrated setae. Modified setae arranged in two rows on the opercular stalks. Abdomen with dorsal uncinigerous tori and ventral fine, long capillary setae with series of comb plates on either side of the main shaft. Uncini with seven teeth and a very long, fine basal process. A pair of curved nuchal hooks, on the dorsal side. Dorsal filiform gills in the thoracic and abdominal segments, much reduced posteriorly. Caudal region achaetous, apodous, segments numerous and indistinguishable.

Synonym (s)
Hermella bicornis Schmarda, Michaelsen, 1892
Pallassia pennata Willey, 1905
Idanthyrsus pennatus Peters Thampi and Rangarajan, 1964
Cryptopomatus geayi Gravier, 1909
(Subjective synonym)
Pallasia pennata (Peters, 1855)
(Objective synonym)
Sabellaria (Pallasia) pennata Peters, 1855
(Objective synonym)

Common Name (s)
Economic Importance and Threats



• Andaman and Nicobar Islands, Andamans INDIA
• Andaman and Nicobar Islands, Nicobars INDIA
• Karachi PAKISTAN
• Red Sea
• Andaman and Nicobar Islands, South Andaman, Aberdeen Bay INDIA

Literature Source(s)
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Achari, GPK (1974) Polychaetes of the family Sabellariidae with special reference to their intertidal habitat Proceedings of the Indian National Science Academy. Part B: Biological Sciences 38 (5&6) 442-455 Available at -
  • Tampi, PRS and Rangarajan, K (1964) Some polychaetous Annelids from the Andaman waters Journal of the Marine Biological Association of India The Marine Biological Association of India, Cochin, India 6(1) 98-123 Available at -
  • James, PSBR ; Thomas, PA ; Pillai, CSG and Achari Kumaraswamy, GP (1969) ´╗┐Catalogue of types and of sponges, corals, polychaetes, crabs and echinoderms in the reference collections of the Central Marine Fisheries Research Institute Bulletin of Central Marine Research Institute CMFRI, Cochin 7 1-66 Available at -

Page last updated on:2011-03-16

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