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PRESENTATION ON TYPE
STUDY OF “HERDMANIA”
Dr. Jagdish kaur
P.G.G.C., Sector 11
CLASSIFICATION OF TYPE
HERDMANIA
1. phylum : chordata
2. subphylum:urochordata
3. class : ascidiacea
4. order : pleurogona
ABOUT HERDMANIA:
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Found in shallow nature
Commonly called sea squirt
It is hermaphrodite
Fertilization is external
Pinkish in colour
Body is covered by test
Basal attached part of it is called foot
Spicules are of two types:
1.Megascleres
2.Microscleres
DIGESTIVE SYSTEM OF HERDMANIA:
 IMPORTANT PARTS OF DIGESTIVE SYSTEM:
1.ALIMENTARY CANAL
2.DIGESTIVE GLAND
1.ALIMENTARY CANAL COMPRISES OF:
1. MOUTH : IT FORMS THE OPENING OF BRANCHIAL
SIPHON
2.BUCCAL CAVITY : IT HAS ITS BASE A STRONG
BRANCHIAL SPHINCTER.THERE IS ALSO A BRANCHIAL
TENTACLES CLOSE TO THE SPHINCTER.IT FOLLOWED BY
PHARYNX
3.PHARYNX: IT IS LARGEST PART OF ALIMENTARY
CANAL.DIVIDED INTO 2 REGIONS:
1.PREBRANCHIAL ZONE
2. BRANCHIAL SAC : GIVES THE APPEARANCE OF
BASKET ,WALLS ARE PERFORATED BY STIGMATA OR
GILL SLITS
4.oesophagus: short curved tube. sharply bend and leads
to stomach.
5. stomach:relatively wide. it leads into intestine
6. intestine: u-shaped tube .two limbs are there:
1.descending limb
2.ascending limb
7.rectum: short narrow tube leads into anus
8:anus: bounded by four lip
2. digestive glands comprises of:
1. liver: 1.drains yellowish brown fluid into stomach .
2.Contains enzymes amylase,protease,weak lipase
2.pyloric gland: mainly consists of branching tubules.
DIGESTION:
IT OCCURS BY PHARYNX WITH THE HELP OF
STIGMATA BEATING , OESOPHAGUS WHERE MUCUS IS ADDED
INTO FOOD , STOMACH WHERE DIGESTION TAKES PLACE BY
ENZYMES WHICH DIGESTS STARCH PROTEASE , INTESTINE
WHERE PROCESS IS COMPLETED COMPLETELY.
BLOOD VASCULAR SYSTEM OF
HERDMANIA:
IMPORTANT PARTS OF BLOOD VASCULAR
SYSTEM IN HERDMANIA ARE GIVEN
BELOW:
(1) HEART AND PERICARDIUM:
1.IT IS A NON CONTRACTILE, ELONGATED AND TRANSPARENT TUBE
RUNNING OBLIQUELY BELOW THE RIGHT GONAD.
2.FILLED WITH A COLOURLESS PERICARDIAL FLUID.
3.THE HEART IS ENCLOSED WITHIN THE PERICARDIUM .
4.THERE ARE NO VALVES BUT A PEAR SHAPED BODY PRESENT MIDWAY
IN THE PERICARDIAL BODY, PROBABLY REGULATES THE FLOW OF
BLOOD IN THE HEART
(2) BLOOD VESSELS : FOUR MAIN BLOOD VESSELS :
1. VENTRAL AORTA:
DIVIDES INTO ANTERIOR AND POSTERIOR LIMBS
LARGEST VESSEL
SENDS TRANSVERSE BRANCHIAL VESSELS THAT CONNECTS WITH
LONGITUDNAL BRANCHIAL VESSEL
ANTERIOR LIMB SENDS PERIPHARYNGEAL VESSELS AND
SUBTENTACULAR VESSELS
(B) DORSAL AORTA:
1. LYING MID-DORSALLY ON THE DORSAL WALL OF BRANCHIAL SAC.
2.IT COMMUNICATES WITH VENTRAL AORTA THROUGH
TRANSVERSE VESSELS OF THE BRANCHIAL SAC , THE CIRCULAR PERIPHARYNGEAL , SUBTENTACULAR VESSELS
(C) BRANCHIOVISCERAL VESSEL:
1.IT ENDS BEHINDS IN TWO BRANCHES: {A} RIGHT OESOPHAGEAL
VESSEL CARRIES BLOOD TO RIGHT PARTS OF BODY
{B} VENTROINTESTINAL VESSEL CARRIES BLOOD TO LEFT PARTS OF
BODY
(D) CARDIOVISCERAL VESSEL: IT GIVES:
{A} RIGHT HEPATIC ARTERY TO RIGHT LOBE OF LIVER
{B} OESOPHAGEOTEST VESSEL SUPPLIES TO OESOPHAGUS
{C} GIVES THREE BRANCHES: MEDIAN DORSAL, LEFT GONADIAL,
GASTROINTESTINAL TEST VESSEL I.E. DORSOINTESTINAL VESSEL AND
DORSAL TEST VESSEL
COURSE OF BLOOD CIRCULATION:
BLOOD:
CONTAINS EIGHT TYPES OF CELLS:
1.ORANGE CELLS
2.SIGNET CELLS
3.GREEN OR MORULA CELLS
4.COMPARTMENT CELLS
5.EOSINOPHILOUS CELLS
6. LYMPHOCYTES
7.MACROPHAGES
8.NEPHROCYTES
DIFFERENT TYPES OF BLOOD CELLS:
RESPIRATORY SYSTEM OF HERDMANIA:
1.BRANCHIAL SAC:
{A} MAIN RESPIRATORY ORGAN
{B} WATER CURRENT IS MAINTAINED BY BEATING OF CILIA
{C}WALL OF BLOOD VESSELS FACILITATES THE GASEOUS EXCHANGE
2. TRABECULAE:
VASCULAR AND CONSTANTLY BATHED IN FRESH SEA WATER
3.TEST:
AMPULLAE PRESENT IN IT HELPS IN BRINGING BLOOD VERY CLOSE
TO SEA FOR GASEOUS EXCHANGE
NERVOUS SYSTEM:
L.S. NERVE GANGLION:
NERVOUS SYSTEM OF HERDMANIA
NERVOUS SYSTEM CONSISTS OF:
{A} CENTRAL NERVOUS SYTEM:
(1.) CONSISTS OF SINGLE PINKISH NERVE GANGLION
(2.)LIES IN INTERSIPHONOL REGION OF BODYWALL
(3.) REFFERED TO AS BRAIN
(4.) NERVE GANGLION COMPOSED OF NERVE CELLS AND NERVE
FIBRES.
{B} PERIPHERAL NERVOUS SYSTEM:
(1.) COMPRISES OF THREE ANTERIOR NERVES AND TWO POSTERIOR
NERVES
(2.)ANTERIOR NERVES SENDS FIBRES TO TEST
(3.) POSTERIOR NERVES SUPPLY BRANCHES TO TENTACLES , MUSCLES
OF ATRIAL SIPHON
SENSE ORGANS:
(A) TANGORECEPTORS
: SENSITIVE TO CONTACT
(B) PHOTORECEPTORS :
{1.} SENSITIVE TO LIGHT
{2.} CONSISTS OF SQUAMOUS CELLS CONTAINING RED PIGMENTED
GRANULES
(C) CHEMORECEPTORS:
A. DORSAL TUBERCLE: 1. LIES IN PREBRANCHIAL ZONE , 2. CONSISTS
OF BASE WITH CONICAL LOBES, 3.IT IS OLFACTORY CUM GUSTATORY
RECEPTOR
B. TENTACLES : REGARDED AS OLFACTORECEPTORS
(D) RHEORECEPTORS: SENSITIVE TO WATER
(E) THERMORECEPTORS : SENSITIVE TO TEMPERATURE
REPRODUCTIVE SYSTEM OF HERDMANIA:
SPERM OF HERDMANIA: OVUM OF HERDMANIA:
REPRODUCTIVE SYSTEM CONSISTS OF :
{A} GONADS:
(1). EACH GONAD CONSISTS OF TEN TO TWENTY FIVE LOBES
(2). MEDIAN LOBE IS BEAN SHAPED
(3). LOBES HAS TWO PARTS: TESTICULAR PART AND OVARIAN PART
{B} GONODUCTS:
(1).EACH GONAD HAS OVIDUCT AND VAS DEFERENS
(2). SPERM DUCTULE LEADS TO VAS DEFERENS
(3). OVARIAN DUCTULE LEADS TO OVIDUCT
{C} GAMETES:
(1).SPERM: HAS HEAD, MIDDLE PIECE, AND TAPERING TAIL
(2).OVUM: 1.CONTAINS YOLK IN IT
2. LARGE EXCENTRIC NUCLEUS
3. CLOSELY INVESTED IN VITTELINE MEMBRANE
4. OUTSIDE IT :INNER CHORION AND OUTER CHORION LIE
5.INNER FOLLICLE AND OUTER FOLLICLE CELLS ARE THERE
THE END