Displaying articles by tag: Zoology Notes

BS Media in Zoology
Friday, 07 July 2017 12:08

AFFINITIES OF UROCHORDATES

The typical tunicate looks like a non-chordate animal. If the life history of such animal is studied, the larval form reveals the chordate characters of that animal. In 1816, Lamarck and Cuvier placed these animals in one class ‘Tunicata’. Allis described a compound Ascidian “Botryllus’ in 1756. KowalevskSi. Worked on…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Affinities of Urochordates
Read 10425 times
BS Media in Zoology
Friday, 07 July 2017 11:29

CLASSIFICATION OF UROCHORDATA

Subphylum Urochordata is divided into three classes.   CLASS 1.  ASCIDIACEA CLASS 2. THALIACEA CLASS 3. LARVACEA (APPENDICULARIA)   CLASS 1. ASCIDIACEA:   These are sedentary tunicates. The body is covered by a test. Pharynx is large and contains gill-slits. Notochord, nerve-cord and tail are absent These are Bisexual animals.…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Classification of Urochordata
Read 12333 times
BS Media in Zoology
Thursday, 06 July 2017 18:42

GENERAL CHARACTERS OF UROCHORDATA

The tunicates were first regarded as sponges. Lamark in 1816 placed Tunicata in between the Radiata and Vermes in his system of classification. Later, they were included in Mollusca. In 1866 Kowalevsky kept them in chordates.   Their chordate features are clearly seen in the larval stages. All Urochordates are…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • General Characters of Urochordata
  • Urochordata General Characters
Read 26623 times
BS Media in Zoology
Thursday, 06 July 2017 18:11

ORGANOGENY IN AMPHIOXUS

The development of organ system is called as Organogeny. In Amphioxus the gastrula elongates in the future anteroposterior direction and the blastopore comes nearer to the posterior end of the dorsal surface and starts the development of organ system.   1. FORMATION OF NEURAL TUBE INAMPHIOXUS: Neural ectoderm cells of…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Organogeny in Amphioxus
Read 2429 times
BS Media in Zoology
Thursday, 06 July 2017 17:01

REPRODUCTION IN AMPHIOXUS: POST FERTILISATION CHANGES

FATEMAP OF FERTILISED EGG OF AMPHIOXUS: Conklin in 1932 studied the fate map of Amphioxus. In 1962 Tunguntung described the egg of amphioxus 4 regions are clearly seen.   Clear cytoplasm occupying the animal pole will mainly become epiderm& ectoderm. The granular yolky cytoplasm near the vegetal pole will become…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Reproduction in Amphioxus
  • Post Fertilisation Changes in Amphioxus
Read 3301 times
BS Media in Zoology
Thursday, 06 July 2017 16:35

REPRODUCTION IN AMPHIOXUS

Amphioxus is a Cephalochordate animal. Its Life history in the early stages shows resemblance with ascidians. HATSCHE’K WILSON. CONKLIN’ worked on the part of embryogenesis of Amphioxus. ‘CONKLINS’ work in more accurate and is recent.   Amphioxus is a unisexual animal. But sexual dimorphism is absent. Amphioxus shows 26 pairs…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Reproduction in Amphioxus
Read 4908 times
BS Media in Zoology
Thursday, 06 July 2017 16:20

ATRIUM IN AMPHIOXUS

In amphioxus a big space is present, called Atrium it is lined by ectoderm. It encloses pharynx, and part of intestine. It opens out through atriopore at 36 myotome in front of caudal fin. The dorsal wall of the atrium is folded. ln the larva the atrium develops at the…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Atrium in Amphioxus
Read 5696 times
BS Media in Zoology
Thursday, 06 July 2017 16:07

ENDOSTYLE IN AMPHIOXUS

In the Urochordate and Cephalochordate animals the ventral side of the pharyhx wilI contains endostyle. It is a glandular ciliated groove present on the floor of the pharynx. This contains alternate bands of ciliated and glandular cells. The gland cell secretes mucus. This mucus will concentrate the food particles of…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Endostyle in Amphioxus
  • TS of Endostyle
Read 2881 times
BS Media in Zoology
Thursday, 06 July 2017 15:53

NOTOCHORD IN AMPHIOXUS

In chordate animals notochord, dorsal tubular nerve cord and pharyngeal slits are present.   In Amphioxus notochord is a cylindrical rod extending the whole length of the body from anterior end to posterior end. it is present below the dorsal nerve cord and above the alimentary canal. The notochord is…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Notochord in Amphioxus
  • TS of Notochord
Read 4566 times
BS Media in Zoology
Thursday, 06 July 2017 15:40

SKELETON IN AMPHIOXUS

Exoskeleton is absent in Branchiostama. Endoskeleton include the notochord, gelatinous rods and plates, fin-ray boxes etc.   1. Notochord in Amphioxus: The notochord of Amphioxus is extending the whole length of the body along the mid-dorsal line just below the central nervous system. The notochord consists of a single longitudinal…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Skeleton in Amphioxus
Read 3308 times
BS Media in Zoology
Wednesday, 05 July 2017 12:18

EXTERNAL CHARACTERS OF AMPHIOXUS

Amphioxus belongs to Cephalochordate. In 1778 Amphioxus was first discovered and described by Palias. He called it a Molluscan animal. In 1834, it was described as a chordate animal by Costa. He called it ‘Branchistoma’. In 1836, Yarrell gave th name Amphioxus. Amphioxus lives in shallow marine waters and burrows…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Characters of Amphioxus
  • External Characters of Amphioxus
Read 8226 times
BS Media in Zoology
Wednesday, 05 July 2017 11:29

CLASSIFICATION AND SYSTEMIC POSITION OF CEPHALOCHORDATE

The sub-phylum Cephalochordata includes a single class Leptocardii, which has single family, Branchiostomidae. The family contains only two genera Branchiostoma and Asymmetron.   The subphylum - Cephalochordata includes Amphioxus or Branchiostoma.   Pallas described this animal first. He named it as Umax lancealatus, He included this in Mollusca. In 1834,…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Classification of Cephalochordate
  • Systemic Position of Cephalochordate
Read 7887 times
BS Media in Zoology
Tuesday, 04 July 2017 19:16

GENERAL CHARACTERS OF CEPHALOCHORDATA

Cephalochordata includes two genera, 1. Asymmetron and 2. Branchiostoma (Amphioxus). Cephalochordates are small fish like animals which show Chordate characters. The notochord extends the entire length of the body. They show a dorsal, tubular neural tube without a definite brain.   GENERAL CHARACTERS:   Body is fish-like and is useful…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Characters of Cephalochordata
Read 33760 times
BS Media in Zoology
Tuesday, 04 July 2017 12:31

CLASSIFICATION PHYLUM CHORDATE

Phylum Chordate is divided into three Sub-Phyla.   SUB-PHYLUM: UROCHORDATA SUB-PHYLUM: CEPHALOCHORDATA SUB-PHYLUM: VERTEBRATA   The first two sub phyla are called lower chordates or PROTOCHORDATES. They are usually called Acrania group. The vertebrata sub-phylum is called CRANIATA group.   1. SUB-PHYLUM: UROCHORDATA:   The urochordate animals belonging to this…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Classification of Chordate
Read 15227 times
BS Media in Zoology
Tuesday, 04 July 2017 11:43

BIOLOGY OF CHORDATES

CHORDATES   The Phylum Chordate includes bilaterally symmetrical, metamerically segmented, triploblastic, enterocoelomate metazoans exhibiting hights complex organization. This phylum is supposed to be one of the most heterogenous and diversified gruop of animal kingdom. The minute sessile cephalodiscus, work-like Balanoglossus, degenerate tunicates, Amphioxus and the true vertebrates have been included…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • Biology of Chordates
Read 4562 times
BS Media in Zoology
Tuesday, 04 July 2017 11:28

GENERAL CHARACTERS OF CHORDATES

The animal kingdom is divided into two sub-kingdoms:   Chordata Non-Chordata   GENERAL CHARACTRS OF CHORDATES   The Chordate characters appear in the developmental stage will persist in the adult or modified in the adult or disappeared in the adult   They are,   1. PRESENCE OF NOTOCHORD: It is…

  • Zoology
  • Zoology Notes
  • Notes
  • Article
  • General Characters of Chordates
  • Chordates General Characters
Read 14105 times
Page 2 of 20