A sea cucumber (Ocnus planci)
|Researched by||Dr Harvey Tyler-Walters||Refereed by||Admin|
|Other common names||-||Synonyms||Cucumaria planci (Brandt, 1835)|
A large sea cucumber up to 15 cm long and 3.5 cm in diameter but usually smaller. The body is tough, stiff, smooth and slightly angular. Usually russet, dark or purple-brown in colour, often with spots or dark lines between each of the five body sections. Tube feet are lighter in colour than the body and arranged in five double rows. The eight large and two small feeding tentacles are branched, leaf-like, and lighter in colour than the body.
Recorded distribution in Britain and Ireland
Recorded from Wider Firth, Orkney; off Runswick Bay, east England; Dogger Bank; Tremadoc Bay, north Wales; southern Ireland; Carlingford and Strangford Lough, Northern Ireland, and sea lochs and inlets of western Scotland.
Recorded from Portugal, the Mediterranean and West Africa (Senegal).
Found on soft muddy sediments in areas of moderate to weak water flow at depths of 2 -175 m. It is epifaunal, congregating on rises in the substratum, pebbles, cobbles, sessile invertebrates or on the fronds of algae.
- Tube feet arranged in double rows.
- Body russet brown and skin smooth.
- Eight large and two small, ventral feeding tentacles.
- Spicules in body wall, mainly knobbed button shaped plates with more than 4 holes, with superficial, small, flat baskets.
Ocnus planci is the unique characterizing species of the biotope IMU.Ocn (see review for details). Ocnus brunneus may be a smaller form of Ocnus planci. Ocnus brunneus is russet brown in colour, with tube feet singly arranged in five rows, growing up to 2.5 cm in length and 0.5 cm in diameter but usually smaller. The taxonomy of Ocnus planci and Ocnus brunneus was discussed in detail by McKenzie (1984 & 1991). McKenzie (1997) suggested that these species should be recorded separately until their taxonomy had been resolved. McKenzie (1991) noted that Ocnus planci had also been confused with Aslia lefevrei. Therefore, some of the records mapped above may have been mis-identified.
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This review can be cited as:
Last Updated: 19/11/2002