Department of Zoology at ANDC/Zoology Museum/Museum specimens/Urochordata

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Phylum Urochordata

Date & Time : 20, June 2024 12:59

General Characteristics of Urochordata

Classification of Urochordata

A Few Examples


Geographical distribution: India, Pacific and the Atlantic oceans and from Malaya and West Indies

Habitat: solitary marine form

Food: microscopic plants and animals i.e. diatoms, algae and infusorians

Characteristic Features:

1. Body: roughly oblong in outline

2. Body Length: 9.5 to 12 cm long

3. Body Colour: pink

4. Attachment of animal is at posterior ventral end by foot

5. Body free end is provided with two external openings of the branchial and the atrial apertures

6. Opening of mouth through branchial aperture or siphon,while anus by atrial aperture

7. Sac-like pharynx perforated by numerous stigmata

8. U-shaped alimentary canal

9. Respiration through branchial – sac. Test also act as an accessory respiratory organ

10. Open – type blood vascular system

11. Excretory organ is neural gland present above the nerve ganglion

12. Hermaphrodite

2. Doliolum

Geographical distribution: Tropical and sub-subtropical waters

Habitat: free- swimming,pelagic form inhabiting the warm water

Characteristic Features:

1. Body: barrel-shaped with the mouth and at opposite end lies anus

2. Test or tunic : thin,transparent and has no cells

3. Open ends of barrel are fringed with lobes

4. In volumnous pharynx oral funnel opens broadly

5. Pharynx: perforated by dorsal and rows of stigmata present ventrally

6. In the pharynx Endistyle and peripharyngeal ciliated bands are present

7. Absence of dorsal lamina and tentacles

8. Stomach small and intestine short and anus open posteriorly

9. Hermaphrodite

10. Near the anterior end dorsal ganglion and subneural glands are situated

11. Life cycle show an alteration of sexually mature adult , the gonozoid with the asexually reproducing phase,the oozoid

3. Salpa

Geographical distribution: Tropical seas

Habitat: free swimming,solitary pelagic forms

Characteristic Features:

1. Body: barrel-shaped with the mouth and atrial aperture present at opposite end

2. transparent test

3. Presence of Endostyle and pharyngeal bands

4. Dorsal lamina present and is known as gill

5. On dorsal surface a single tentacle is present

6. Digestive system and heart is present in a spot called nucleus

7. Eye is present near near the nerve ganglion

8. In front of the pharynx dorsal tubercle is present

9. Presence of subneural gland ventral to the ganglion

10. Salpa is found in 2 forms:

a) Asexual phase or oozoid

b) Sexual phase or blastozooid

3. Ciona

Geographical distribution: Western region

Habitat: solitary marine form attached to rocks

Characteristic Features:

1. Body: cylindrical ,tubular ,transparent and longer than broad

2. Body Length: 3.5-5inches

3. Body covered with thin transparent test or mantle

4. Opening of mouth is in branchial siphon and anus into atrial-siphon

5. Branchial aperture is 8-lobed while atrial aperture is 6-lobed

6. Longitudinal folds absent in pharynx

7. U – shaped alimentary canal consist of pharynx, oesophagus, stomach and intestine

8. Rectangular stigmata

9. Horse-shoe shaped dorsal tubercle

10. Hermaphrodite and protogynous