What are Protochordates what are the difference between subphyla Urochordates and cephalochordates and comparrision between Urochordates and cephalochordates

1. NAME :- MARYAM SHAMSUL ISLAM
SHAIKH
CLASS :- MSc – 1 SEM 2
COLLEGE :- MAHARSHI DAYANAND
COLLEGE

2. Content
1) What are chordates
2) Classification of chordates
3) Protochordates
4) Urochordata
5) Herdmania
6) Cephalochordata
7) Branchiostoma , Amphioxus
8) Comparison of characteristic between subphyla Urochordates and
Cephalochordates
9) Reference

3. WHAT ARE CHORDATES?

30. Urochordata or Tunicata:
General characters –
∆ Habitat –
• Marine, free swimming or attached with rocks.
• Adult – Fixed
Larva – Free swimming
∆ They have test all over their body.
∆ Made up of Tunicine.
∆ Notochord is found only in tail of tadpole larva.
∆ Chordate characters are found only in the tail region of
tadpole larva, urochordata.

31. ∆ Dorsal tubular nerve cord is found in nerve system, which is present only in
larva stage.
∆ In adult stage, nerve cord is modified into a neural ganglion.
∆ Reproduction –
• Asexual reproduction.
• By budding
• OVO- testes
∆ Fertilization –
• They show cross fertilization.
• Swimming larva stage tadpole larva.
Urochordata or Tunicata:

32. ∆ Members of the subphylum show “Retrogressive metamorphosis”.
∆ Only one Chordate character is found.
∆ In adult i.e pharyngeal gill clefts are found.
Urochordata or Tunicata:

33. Urochordata or Tunicata:
• Examples –
• Herdmania – Sea-potato or sea squits
• Ascidia

34. Herdmania
Systematic position :-
Phylum – Chordata
Sub-phylum – Urochordata
Class – Ascidiacea
Sub-class – Pleurogona
Order – Stolidobranchia
Family – Pyuridae
Genus – Herdmania (sea squirt)

35. Cephalochordata :
• Found in shallow sea water.
• They form burrows.
• Body is segmented.
• No head only trunk and tail is present.
• Alimentary canal is complete.
• Ciliary feeder.
• Blood vascular system is closed type and respiratory pigment
absent.

36. • Nervous system – Dorsal, tubular, hollow nerve cord.
• Notochord – Remain extended from one end of the body to the
other end throughout the life.
• Unisexual
• Fertilization is external.
• Development is indirect.
• First complete Chordata animals.
Cephalochordata :

37. Cephalochordata :
• Example –
• Branchiostoma or Amphioxus (Lancelet).

38. Branchiostoma
(Amphioxus) The lancelet
Systematic position :-
Phylum – Chordata
Group – Acrania
Sub-Phylum – Cephalochordata
Class – Leptocardii
Family - Branchiostomidae

40. Comparison of characteristics between
Subphyla Urochordata and Cephalochordata
Characters Urochordates Cephalochordates
Distribution Marine, world wide Marine, world wide
Habits and habitat Solitary or colonial fixed or free
swimming
Solitary burrowing and free
swimming
Shape Degenerate , bag like Fish-like laterally compressed
Body division Unsegmented without head and
tail
Segmented without distinct head
Post anal tail Absent Present
Fins Absent Median-fins
Coelom Absent, replaced by atrial cavity Reduced by atrial cavity

41. Characters Urochordates Cephalochordates
Atrial cavity Greatly developed Well developed
Notochord Only in larval tail, absent in adult Persistent throughout life
Muscles Unsegmented Metamerically segmented as
myotomes
Digestive tube Complete coiled Complete straight
Feeding mechanism Ciliary Ciliary
Respiratory organs Absent, respiration through body
surface
Absent, respiration through body
surface
Heart Well developed muscular heart Heart absent
Excretory Organs Neural gland, pyloric gland and
nephrocytes
Protonephridia
Nervous system
Sexes United Separate
Comparison of characteristics between
Subphyla Urochordata and Cephalochordata

42. Characters Urochordates Cephalochordates
Gonads One pair Numerous pairs metamerically
arranged
Gonoducts Present Absent
Food Planktonic microorganism’s Planktonic microorganism’s
Feeding habit Microphagus Microphagus
Water current Enters bronchial sac through mouth
and through atriopore
Enters branchial sac through
mouth, reaches atrial cavity
through gill slits and outside
through atriopore
Reproduction Only sexual, sexes united some
reproduce asexually by budding
Only sexual,sexes separate, no
asexual reproduction
Development Indirect with Retrogressive
Metamorphosis
Indirect with Metamorphosis
Comparison of characteristics between
Subphyla Urochordata and Cephalochordata

43. Reference
• R.l kotpal book of Vertebrates