CLASSIFICATION OF CIONA

PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present)

GROUP :- ACRANIATA (No head, cranium or brain)

SUB-PHYLUM :- UROCHORDATA (Marine. Body covered by a thick test. Notochord present only in larval tail)

CLASS :- ASCIDIACEA (Test with scattered muscles. Many pharyngeal gill-slits. Bottom-dwelling).

ORDER :- ENTEROGONA  (Neural gland ventral to nerve ganglion. Gonad one).

FAMILY :- CIONIDAE

Genus :  Ciona

GEOGRAPHICAL DISTRIBUTION

  • Ciona is a common mono-ascidian found in shallow waters.

HABIT AND HABITAT

  • Solitary and sedentary animal found in shallow waters attached with rocks.
CIONA DIAGRAM

GENERAL CHARACTERSTICS OF CIONA

  • Ciona resembles with Herdmania and measures 9 to 12 cm in length.
  • Body of the animal cylindrical, tubular, transparent and longer than broad.
  • It contains 8-lobed branchial siphon and 6-lobed atrial siphon anteriorly. 
  • Branchial and atrial siphons contain mouth and atriopore respectively. Tentacles present at the base of branchial siphon. One left side nerve ganglia present.
  • Body covered by a transparent test and through the test, prominent thick longitudinal muscle bands can be seen. Below test is mantle.
  • Alimentary canal is complete, V-shaped and consists of pharynx, oesophagus, stomach and intestine and it lies in the epicardial cavity. Heart is surrounded by pericardium.
  • Different parts of gut occupy the same topographical parts as that in Herdmania. The gill-slits are rectaagular. The dorsal lamina present. Intestine contains typhlosole. Running parallel with the endostyle are right and left ciliated bands which continue posteriorly as retropharyngeal bands. 
  • Gonads lie in the loop of intestine. Gonads open by genital pore through the genital duct.
  • Longitudinal muscle bands are clearly seen. 
  • Fertilization external and the floating egg develops into an Oikopleura-like larva which settles and undergoes metamorphosis to change into adult.
CIONA

SPECIAL FEATURES

  • Ciona is hermaphroditic and protogynous. The blood of Ciona is rich in a green pigment, called as haemovanadin, containing vanadium produced by vanadocytes. The pigment probably does not take part in oxygen transport. Ciona intestinalis is the common species.

IDENTIFICATION

  • The animal contains thick longitudinal muscle bands and above features hence, it is Ciona.
CIONA
CIONA

REFERENCES

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