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Paridotea munda (Family Idoteidae)

Blunt-tailed Sea Centipede, or Little Sea Centipede


The Blunt-tailed Sea Centipede's distribution range includes NSW, Vic, Tas and SA. (NSW, VIC, TAS, SA)


The Blunt-tailed Sea Centipede is a small, long, thin crustacean that superficially looks like a cross between a prawn and a centipede. It grows to a length of 22 mm. The body surface is smooth, but dull when dry, and is not shiny like the other sea centipedes. Its abdomen consists of a single segment, with faint sutures crossing it. The second and third joints of the first antennae are about the same length. Its abdomen end is blunt with two faint bumps at the edges. Its relation the Sharp-tailed Sea Centipede, P. ungulata, has two sharp tail tips.

The Blunt-tailed Sea Centipede is usually olive or pinkish-brown in colour. This individual from southern Tasmania was rich light green to match the Sea Lettuce, Ulva lactuca, frond on which it was clinging. Hale (1927-9) describes a specimen from Port Willunga, SA, that exactly colour matched the olivaceous colour "of the vegetation to which it clings", but does describe others that "were pinkish-brown, with a pale, elongated spot, outlined in black, at each side of the segments of the thorax".

Ecology/Way of Life:

The Blunt-tailed Sea Centipede occurs at low tide fringe, in pools and gutters down to three metres. It occurs on algae that is the same colour as itself. It swims using its rapidly moving pleopods. Its first three legs are held straight forwards, while the last four pairs of legs are held backwards, so that the legs do not help in the swimming at all. The uropods open downwards, and do not move. When the pleopods stop their rapid movements, the uropods close. The sea centipede then slowly drops, with its legs extended, ready to grasp a frond of algae, the same colour as itself.

Interaction with Humans/Threats:

This interesting creature is only mentioned in Hale (1927-9) and in no other recent field guide or common reference book, with the exception of my book, so it is difficult to guess what its conservation status is at the moment.

Further Reading:

Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. p.45, New Holland Press, Sydney.

Hale, H. M. (1927-9). The Crustaceans of South Australia. Parts I and II. p.319-10. Reprinted 1976. Government Printer, South Australia.

Jones, D. and Morgan, G. (1994). A Field Guide to Crustaceans of Australian waters. Reed.


Text, map and photograph by Keith Davey.

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