Planodasys littoralis   Rao,  1993 (Gastrotrich)
Organism information awaits expert curation

Size: Length 760-800 µm and a maximum width 85-90 µm.

The whole body is transparent, dorsoventrally flattened and ribbon-like. Anterior end is bluntly rounded, while the posterior end slightly tapers into a tail with two terminal symmetrical lobes. The tail lobes are distinct and triangular with broad bases and tapering tips. The lobes are 15-20 µm long and highly retractable. The head is indistinct and merges with the posterior trunk. Dorsal surface of body is smooth without any cuticular ornamentation as hooks or scales. Epidermis contains 8 pairs of oval and dorsolateral glands measuring about 10 µm in diameter. Head with two shallow lateral pits, each carrying a pestle organ sensory in function. Anterior and lateral margins of head and trunk bear sensory hairs. Ventral ciliation occurs in two distinct longitudinal bands. Ventral glands indistinct.
Adhesive tubes occur in three paired groups, namely, anterior, lateral and posterior. Anterior tubes occur disposed in a diagonal row broken in the middle on ventral surface of head just behind buccal cavity. Each group consists of 6 tubes directed forwards. Lateral tubes extend from just behind anterior tubes close to the posterior end. There are about 30 lateral tubes on either side of the body. Each tail lobe bears 8 posterior tubes, 4 tubes being disposed on either side. The tubes are directed backwards, progressively increase in size and attain a length of 6-10 µm, the distal two tubes being always the longest. Adhesive tubes are absent on the posterior border of the animal between the two tail forks.
Mouth is 20 µm wide, terminal and inclined to ventral surface. It lacks any accessory structures. Buccal cavity is shallow, cup-shaped, with thin cuticularized walls. Pharynx is about 260 µm long with numerous refringent granules and occupies nearly 1/3rd of the total gut length. Pharyngeal pores are well developed and occur close to the hind end of pharynx. The gut following the pharynx is almost straight and consists of a broad stomach and slender intestine. Anus is subterminal and opens on the ventral surface.

The species is a hermaphrodite with paired testes and ovaries situated lateral to the digestive tract. The testes run from just behind the pharyngeal knobs along the anterior part of stomach. Ovaries lie just behind testes. Position of male genital pore is indistinct, but the vasa deferentia converge posteriorly anterior to the egg cells. A cylindrical bursa copulatrix characteristic of the genus occurs posteriorly, running close to the intestine to the level of anus. The bursa is slightly bent and muscular, with a conspicuous internal ciliated canal opening ventral surface close to anus.

Synonym (s)

Common Name (s)
Economic Importance and Threats

Habitat:  Demersal, Sandy, Coastal


• Andaman and Nicobar Islands, Andaman Islands (Lat: 10) (Long: 93) INDIA
• Andaman and Nicobar Islands, Harmindar Bay (Lat: 10.75) (Long: 92.5) INDIA
• Andaman and Nicobar Islands, Harmindar Bay INDIA (Record: 25/03/1990) (Depth: 0.1 mts)
• Andaman and Nicobar Islands, South Bay INDIA (Record: 26/03/1990)
• Andaman and Nicobar Islands, Harmindar Bay INDIA

Literature Source(s)
  • Rao, GC (1993) Littoral meiofauna of Little Andaman Records of the Zoological Survey of India. Occasional paper no. 155 ZSI, Calcutta 120 pp Available at - NIO, Goa
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Priyalakshmi, G and Menon, NR (2008) Indian marine Gastrotricha Available at -
  • Sealifebase Available at -

Page last updated on:2010-11-22

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