Characteristics of Protochordata

  • All the protochordates are marine, solitary and may be micro figure.
  • The body is covered by single layer of cunic which is Transport and made of single layered of epithelium.
  • In the body of animal Skelton absent. In some animal a thick membrane present which support the body.
  • In pharynx there present pharyngeal Gill's Slits which are supported by cilia.
  • The Notochord present whole of the body are some part of body and found in any stage of life.
  • In cephalochordata the Notochord present whole length of the body and in urochordata the Notochord present in tail region of larva but in hemichordata the Notochord present in buccal divertucullum and not well develope.
  • In animal the nature of food material is help by dorsal lamina and endostyle.
  • The circulatory system is well develope and consist of heart, blood vessels and sinuses.
  • The nerve system is primitive and much developed in cephalochordata.
  • In urochordata the nervous system present only in larval condition but in adult ganglion.
  • The excretion takes place by nephredia and in some animal change into glomerulus and neural gland.
  • The reproduction by whole type asexual and sexual and the development is direct and indirect.

Protochordate Examples | Protochordates Examples

E.g., Balanoglossus, Herdmania, Amphioxus.

Classification of protochordata

The protochordates is classified into three group or Sub-phylum on the basis of presence of Notochord in the body. 
  1. Hemichordata
  2. Urochordata
  3. Cephalochordata

Hemichordata

  • The animals are solitary or colonial and most of them are tubicolous soft and fragile.
  • The body is divided into three region.
a) Proboscis
b) Collar
c) Trunk
  • The body of animal has tentaculated arms present on second segment of body.
  • The buccal divertucullum which is modified form of Notochord present in Proboscis region.
  • The alimentary canal is straight and open into anus and also "U" shaped digestive track.
  • Several pair of Gill's glits present on the dorsal surface of anterior part of innnerside of collor.
  • The animals are muco-cilliary feeder.
  • The nervous system is primitive type.
  • The circulatory system is open type.
  • The excretion takes place by glomerulus.
  • The reproduction is mostly sexual.
  • The Development may be direct or indirect and takes place through Tornaria larva.
  • The Sub-phylum hemichordata is divided into three classes.
a) Enteropneusta
b) Pterobranchia
c) Planctosphaeraidea

Urochordata

Uro - Tail
Chorda - Notochord
  • The urochordate are marine, solitary or colonial and fixed or pelegic. The animals are distributed to littoral or abysal.
  • The body are differentiated in shape and size. The body is covered by a hard covering called tunic or test. The tunic is composed of tunicine [(C6H10O5)n] which is cellulose like glycogen.
  • The tunic are transparent in some animal and translucent or opaque.
  • The tunicates have two pores as atrial and branchial siphon.
  • The pharynx is situated in archentrial cavity and provided dorsal lamina and endostyle grave.
  • The wall of pharynx perforated by ciliated Gill's Slits.
  • The tunicates feeds upon microscopic organism by cilliary feeding.
  • The heart is ventrally located in pericordial envelope.
  • The nervous system is represented by small ganglion.
  • The sex are United and gonads are partialy male and partialy female.
  • Some tunicates may be unisexual most are oviporous and some are viviparous.
  • Metamorphosis is retrogressive with degeneration of advanced character.

Cephalochordata

  • The animals are totally marine and distributed I  shallow sea water.
  • The animals are mostly sedentric and buried with my anterior body and project out above the bottom.
  • The body is small and 5-8 cm long fish like and transparent.
  • In animals the head is lacking and the body has trunk and tail.
  • In animal appendages paired is absent and median find present.
  • Endo-skelton in the body is absent and Epidermis is single layered.
  • The muscle are dorso lateral segmented into myotoms.
  • The coelom is anterocoelous.
  • The Notochord is rod like persistent sprit from rostrum to tail so the name given as cephalochordata.
  • The digestive system is well develope pharynx I large.
  • Animals are filter filler.
  • Respiration takes place general surface of the body so there is absence of any respirative organ.
  • The circulatory system well developed without heart and respirative pigment 
  • Hepatic portal system present.
  • The excretion takes place by protomephredia with solanocytes.
  • The Nervechord is tubulor present on dorsal side of body without nerve ganglian and brain.
  • The sexes are seprate, gonduct absent.
  • Fertilization is external takes place in sea water.
  • The development is indirect and takes place by swimming larva.