Phylum

1. CLASSIFICATION OF HEMICHORDATES
PRESENTED BY: HADIA IFTIKHAR
ROLL # 22011514-004
BS-ZOOOLOGY
DEPARTMENT OF ZOOLOGY

2. CONTENTS
• PHYLUM HEMICHORDATA
• CLASSIFICATION OF HEMICHORDATA
• CLASS ENTERONEUSTA
• General Characters
• Maintainance Functions
• CLASS PTEROBRANCHIA
• General Characters
• Maintainance Functions
• CLASS PLANCTOSPHAEROIDEA
• REFRENCES

3. PHYLUM HEMICHORDATA
hemi,half+chorda,cord
Habitat ;
Marine
Environment
Deuterostomates
(anus develops first)

4. General Characters
Half
Cord
Triploblastic
Ciliated
Pharynge
al Slits
Open
Circulatory
System
Complete
Digestive
System
Dorsal or
tubular
nerve cord
Dioecious
Organisms

5. cont...
They have three body regions
Probocis Collar Trunk

6. CLASSES OF HEMICHORDATES
CLASS
ENTEROPNEUSTSA
CLASS
PLACTOSPHAEROIDEA
CLASS
PTEROBRANCHIA

7. CLASS
ENTEROPNEUSTA
• 70 Species
• 10-40 cm long
• some about 2m
long
• U-shaped
burrows
• acorn worms

8. GENERAL CHARACTERS
• Marine Habitat
• Ciliated Pharyngeal Slits
• Open Circulatory System
• Complete igestive Tract
• Proboscis;short and conical projection at the anterior
end
• Collar; ring like
• Trunk ; elongated
• Ciliated epidermis and gland cells

9. Maintainance Functions
• Feeding
• probocis
• cilia
• mucous
• mucoid string
• Pharyngeal slits

10. Cont...
Digestion
• Simple tube
• hepatic sacs
• complete
digestive
system
• from mouth to
anus

11. Respiration
• Diffusion
• Pharyngeal
Slits
• diffusion
(blood and
water)
Excretion
• Pores in collar
• Ammonia
• Diffusion
• Through anus

12. Cont...
Circulatory System
• 1 dorsal and 1 ventral blood
vessel
• anteriorly and posteriorly
circulates
• blood colorless
• distributes nutrients
• open circulatory system
• Glomerulus
Nervous System
• ectodermal in
origin
• a dorsal and a
ventral nerve
cord
• neve plexus
• no major
ganglia
• sensory
receptors

13. cont...
Reproduction and
development
• Dioecious
• 2 rows of gonads
• external fertilization
• tornaria larvae

14. CLASS
PTEROBRANCHIA
• deep oceans
• 20 species
• 0.1 to 5 mm long
• form asexual colony

15. GENERAL
CHARACTERS
• Triploblastic
• 3 body regions
• probocis; shield- like
• Collar ; 2-9 arms and tentacles
• Trunk; U- shaped
• Complete digestive tract
• Open Circulatory System
• Dioecious

16. MAINTAINANCE
FUNCTIONS
Feeding
• Cilia
• mucoid string
• Arms
• Tentacles
• filter feeding

17. Digestion
• U-shaped
• complete
digestive tract
• mouth to anus
• enzymes in
stomach
• digestion and
absorption

18. cont...
Excretion
• ammonia
• diffusion
• anus (the last part of
digrstive tract)
Respiration
• Gills
• pharyngeal
slits

19. Cont....
Circulatory System
• Contractile Heart-
like blood vessel
• sinuses
• open circulatory
system.
Nervous System
• no proper system
• intra-epidermal
• concentration of
nerves at the base
of tentacles

20. Cont...

21. Cont....
Reproduction and
development
• Dioecious
• Asexual colony
• Sexualy also
• External fertilization
• Planula- like larvae
• Tube of female
• Metamorphosis
• Adult

23. Class Planctosphaeroidea
• 1 Specie
• P. pelagia
• U-Shaped digestive tract
• cilia band for food capturing
• Mucous secreting gland
• feeding
• deterring predators and parasites
• Free swimming
larvae
• Tornaria
• similar to
Enteropneusta’s
larvae but large in
size .

24. Cont...

25. Refrences
Websites
https://www.britannica.com [11am] [12/5/23]
https://www.greeksforgreeks.org [3 pm] [12/5/23]
https://www.biologydiscussion.com [5 pm] [13/5/23]
https://www.sciencedirect.com [7 pm] [ 13/5/23]
https://www.journals.uchicago.edu [8pm] [13/5/23]
Books
Zoology by Stephen A. Miller and John P. Harley , fifth
edition , chapter no.17, page no. 255- 265
Zoology By Stephen A Miller and John P. Harley , tenth

26. QUESTIONS???