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Theories to explain the origin of Bilateria from Radiata
1. Ctenophore-polyclad theory
This theory was proposed by Kowalevsky (1880) and Arnold Lang (1881-84) and emphasises that polyclads evolved from ctenophore-like ancestor. Modern polyclads, such as Leptoplana and Notoplana are marine, free-living, bottom dwelling turbellarians that belong to Order Polycladida or Phylum Platyhelminthes. They creep on the bottom and use their ventral mouth to feed on detritus. On the other hand ctenophores are freely floating animals exhibiting radial as well as bilateral symmetry that is also termed as biradial symmetry. Ciliary bands are radially placed on the body while a pair of antennae is bilateral. A ctenophore-like ancestor could have given rise to bilaterally symmetrical animals by acquiring bottom crawling mode of life. There are some crawling ctenophores existing today, e.g. Ctenoplana and Coeloplana.
2. Ctenophore-trochophore theory
This theory takes into consideration the larval stages of coelenterates, ctenophores, helminthes and annelids and tries to establish evolutionary relationship among them. Planula larva of coelenterates has elongated and cylindrical body that is ciliated all over. Cydippid larva of ctenophores is also ovoid in shape but has longitudinal ciliary bands arranged radially around the body. Muller’s larva of Polycladida (Helminthes: Turbellaria) also has ciliary bands on swimming arms and apical tuft of cilia on the anterior side. Mouth is ventral in this larva and there is no anus. The trochophore larva of Polychaeta resembles Muller’s larva in having ciliary bands and apical tuft of cilia and ventral mouth. Since cydippid larva of ctenophore, Muller’s larva of polyclads and trochophore larva of polychaetes all resemble one another in structure and ciliary band, this theory considers larvae of acoelomate bilateria (flat worms) as early stages of trochophore.
3. Planuloid-Acoeloid theory
This theory was first proposed by Ludwig von Graff (1882) and later elaborated by L. H. Hyman (1951). The theory postulates that the primitive acoelomate bilateria (helminths) evolved from some planuloid ancestor which was very similar to the planula larva of coelenterates. The planuloid ancestor must have been free-living, radially symmetrical, ciliated and with a diffused nerve net. Such planuloid must have developed into a gastrula-like ancestor by the formation of mouth and archenteron and adopted a bottom creeping mode of living rather than free swimming habit of planula. Creeping habit produced cephalisation of nervous system towards the anterior side and since the food was available at the bottom, the anterior mouth moved to the ventral side and the body became dorso-ventrally flattened, as is the case in turbellarian helminths of today.
yeh waali theories ?
Haan bhai... yahi bol rhe the... yai hona chahiye... theories me
Dang it main yeh naam nahi likhe baaki massala yahi daala hai
Haha.. sahi hai h sahi h...(y). But dekhiyega... avg scores upar honge is baar zoology ke bhi... as accordingly kyuki other optionals were also easy. Btw essay kaun kaun sa likhe?
Last year waala examiner na hua to hoga uppar varna Ram nam satya ho jaye ga.... Essay classrooms wala aur Natural rights waala
Theories to explain the origin of Bilateria from Radiata
1. Ctenophore-polyclad theory
This theory was proposed by Kowalevsky (1880) and Arnold Lang (1881-84) and emphasises that polyclads evolved from ctenophore-like ancestor. Modern polyclads, such as Leptoplana and Notoplana are marine, free-living, bottom dwelling turbellarians that belong to Order Polycladida or Phylum Platyhelminthes. They creep on the bottom and use their ventral mouth to feed on detritus. On the other hand ctenophores are freely floating animals exhibiting radial as well as bilateral symmetry that is also termed as biradial symmetry. Ciliary bands are radially placed on the body while a pair of antennae is bilateral. A ctenophore-like ancestor could have given rise to bilaterally symmetrical animals by acquiring bottom crawling mode of life. There are some crawling ctenophores existing today, e.g. Ctenoplana and Coeloplana.
2. Ctenophore-trochophore theory
This theory takes into consideration the larval stages of coelenterates, ctenophores, helminthes and annelids and tries to establish evolutionary relationship among them. Planula larva of coelenterates has elongated and cylindrical body that is ciliated all over. Cydippid larva of ctenophores is also ovoid in shape but has longitudinal ciliary bands arranged radially around the body. Muller’s larva of Polycladida (Helminthes: Turbellaria) also has ciliary bands on swimming arms and apical tuft of cilia on the anterior side. Mouth is ventral in this larva and there is no anus. The trochophore larva of Polychaeta resembles Muller’s larva in having ciliary bands and apical tuft of cilia and ventral mouth. Since cydippid larva of ctenophore, Muller’s larva of polyclads and trochophore larva of polychaetes all resemble one another in structure and ciliary band, this theory considers larvae of acoelomate bilateria (flat worms) as early stages of trochophore.
3. Planuloid-Acoeloid theory
This theory was first proposed by Ludwig von Graff (1882) and later elaborated by L. H. Hyman (1951). The theory postulates that the primitive acoelomate bilateria (helminths) evolved from some planuloid ancestor which was very similar to the planula larva of coelenterates. The planuloid ancestor must have been free-living, radially symmetrical, ciliated and with a diffused nerve net. Such planuloid must have developed into a gastrula-like ancestor by the formation of mouth and archenteron and adopted a bottom creeping mode of living rather than free swimming habit of planula. Creeping habit produced cephalisation of nervous system towards the anterior side and since the food was available at the bottom, the anterior mouth moved to the ventral side and the body became dorso-ventrally flattened, as is the case in turbellarian helminths of today.
yeh waali theories ?
Haan bhai... yahi bol rhe the... yai hona chahiye... theories me
Dang it main yeh naam nahi likhe baaki massala yahi daala hai
Haha.. sahi hai h sahi h...(y). But dekhiyega... avg scores upar honge is baar zoology ke bhi... as accordingly kyuki other optionals were also easy. Btw essay kaun kaun sa likhe?
Last year waala examiner na hua to hoga uppar varna Ram nam satya ho jaye ga.... Essay classrooms wala aur Natural rights waala
Theories to explain the origin of Bilateria from Radiata
1. Ctenophore-polyclad theory
This theory was proposed by Kowalevsky (1880) and Arnold Lang (1881-84) and emphasises that polyclads evolved from ctenophore-like ancestor. Modern polyclads, such as Leptoplana and Notoplana are marine, free-living, bottom dwelling turbellarians that belong to Order Polycladida or Phylum Platyhelminthes. They creep on the bottom and use their ventral mouth to feed on detritus. On the other hand ctenophores are freely floating animals exhibiting radial as well as bilateral symmetry that is also termed as biradial symmetry. Ciliary bands are radially placed on the body while a pair of antennae is bilateral. A ctenophore-like ancestor could have given rise to bilaterally symmetrical animals by acquiring bottom crawling mode of life. There are some crawling ctenophores existing today, e.g. Ctenoplana and Coeloplana.
2. Ctenophore-trochophore theory
This theory takes into consideration the larval stages of coelenterates, ctenophores, helminthes and annelids and tries to establish evolutionary relationship among them. Planula larva of coelenterates has elongated and cylindrical body that is ciliated all over. Cydippid larva of ctenophores is also ovoid in shape but has longitudinal ciliary bands arranged radially around the body. Muller’s larva of Polycladida (Helminthes: Turbellaria) also has ciliary bands on swimming arms and apical tuft of cilia on the anterior side. Mouth is ventral in this larva and there is no anus. The trochophore larva of Polychaeta resembles Muller’s larva in having ciliary bands and apical tuft of cilia and ventral mouth. Since cydippid larva of ctenophore, Muller’s larva of polyclads and trochophore larva of polychaetes all resemble one another in structure and ciliary band, this theory considers larvae of acoelomate bilateria (flat worms) as early stages of trochophore.
3. Planuloid-Acoeloid theory
This theory was first proposed by Ludwig von Graff (1882) and later elaborated by L. H. Hyman (1951). The theory postulates that the primitive acoelomate bilateria (helminths) evolved from some planuloid ancestor which was very similar to the planula larva of coelenterates. The planuloid ancestor must have been free-living, radially symmetrical, ciliated and with a diffused nerve net. Such planuloid must have developed into a gastrula-like ancestor by the formation of mouth and archenteron and adopted a bottom creeping mode of living rather than free swimming habit of planula. Creeping habit produced cephalisation of nervous system towards the anterior side and since the food was available at the bottom, the anterior mouth moved to the ventral side and the body became dorso-ventrally flattened, as is the case in turbellarian helminths of today.
yeh waali theories ?
Haan bhai... yahi bol rhe the... yai hona chahiye... theories me
Dang it main yeh naam nahi likhe baaki massala yahi daala hai
Haha.. sahi hai h sahi h...(y). But dekhiyega... avg scores upar honge is baar zoology ke bhi... as accordingly kyuki other optionals were also easy. Btw essay kaun kaun sa likhe?
Last year waala examiner na hua to hoga uppar varna Ram nam satya ho jaye ga.... Essay classrooms wala aur Natural rights waala
Theories to explain the origin of Bilateria from Radiata
1. Ctenophore-polyclad theory
This theory was proposed by Kowalevsky (1880) and Arnold Lang (1881-84) and emphasises that polyclads evolved from ctenophore-like ancestor. Modern polyclads, such as Leptoplana and Notoplana are marine, free-living, bottom dwelling turbellarians that belong to Order Polycladida or Phylum Platyhelminthes. They creep on the bottom and use their ventral mouth to feed on detritus. On the other hand ctenophores are freely floating animals exhibiting radial as well as bilateral symmetry that is also termed as biradial symmetry. Ciliary bands are radially placed on the body while a pair of antennae is bilateral. A ctenophore-like ancestor could have given rise to bilaterally symmetrical animals by acquiring bottom crawling mode of life. There are some crawling ctenophores existing today, e.g. Ctenoplana and Coeloplana.
2. Ctenophore-trochophore theory
This theory takes into consideration the larval stages of coelenterates, ctenophores, helminthes and annelids and tries to establish evolutionary relationship among them. Planula larva of coelenterates has elongated and cylindrical body that is ciliated all over. Cydippid larva of ctenophores is also ovoid in shape but has longitudinal ciliary bands arranged radially around the body. Muller’s larva of Polycladida (Helminthes: Turbellaria) also has ciliary bands on swimming arms and apical tuft of cilia on the anterior side. Mouth is ventral in this larva and there is no anus. The trochophore larva of Polychaeta resembles Muller’s larva in having ciliary bands and apical tuft of cilia and ventral mouth. Since cydippid larva of ctenophore, Muller’s larva of polyclads and trochophore larva of polychaetes all resemble one another in structure and ciliary band, this theory considers larvae of acoelomate bilateria (flat worms) as early stages of trochophore.
3. Planuloid-Acoeloid theory
This theory was first proposed by Ludwig von Graff (1882) and later elaborated by L. H. Hyman (1951). The theory postulates that the primitive acoelomate bilateria (helminths) evolved from some planuloid ancestor which was very similar to the planula larva of coelenterates. The planuloid ancestor must have been free-living, radially symmetrical, ciliated and with a diffused nerve net. Such planuloid must have developed into a gastrula-like ancestor by the formation of mouth and archenteron and adopted a bottom creeping mode of living rather than free swimming habit of planula. Creeping habit produced cephalisation of nervous system towards the anterior side and since the food was available at the bottom, the anterior mouth moved to the ventral side and the body became dorso-ventrally flattened, as is the case in turbellarian helminths of today.
yeh waali theories ?
Haan bhai... yahi bol rhe the... yai hona chahiye... theories me
Dang it main yeh naam nahi likhe baaki massala yahi daala hai
Haha.. sahi hai h sahi h...(y). But dekhiyega... avg scores upar honge is baar zoology ke bhi... as accordingly kyuki other optionals were also easy. Btw essay kaun kaun sa likhe?
Last year waala examiner na hua to hoga uppar varna Ram nam satya ho jaye ga.... Essay classrooms wala aur Natural rights waala
Acha sahi h...thoda alag hai... maine farming aur social media... Btw copy checking start ho gyi hai...abi 10-12 din tak days compulsory papers ki chalegi..
Theories to explain the origin of Bilateria from Radiata
1. Ctenophore-polyclad theory
This theory was proposed by Kowalevsky (1880) and Arnold Lang (1881-84) and emphasises that polyclads evolved from ctenophore-like ancestor. Modern polyclads, such as Leptoplana and Notoplana are marine, free-living, bottom dwelling turbellarians that belong to Order Polycladida or Phylum Platyhelminthes. They creep on the bottom and use their ventral mouth to feed on detritus. On the other hand ctenophores are freely floating animals exhibiting radial as well as bilateral symmetry that is also termed as biradial symmetry. Ciliary bands are radially placed on the body while a pair of antennae is bilateral. A ctenophore-like ancestor could have given rise to bilaterally symmetrical animals by acquiring bottom crawling mode of life. There are some crawling ctenophores existing today, e.g. Ctenoplana and Coeloplana.
2. Ctenophore-trochophore theory
This theory takes into consideration the larval stages of coelenterates, ctenophores, helminthes and annelids and tries to establish evolutionary relationship among them. Planula larva of coelenterates has elongated and cylindrical body that is ciliated all over. Cydippid larva of ctenophores is also ovoid in shape but has longitudinal ciliary bands arranged radially around the body. Muller’s larva of Polycladida (Helminthes: Turbellaria) also has ciliary bands on swimming arms and apical tuft of cilia on the anterior side. Mouth is ventral in this larva and there is no anus. The trochophore larva of Polychaeta resembles Muller’s larva in having ciliary bands and apical tuft of cilia and ventral mouth. Since cydippid larva of ctenophore, Muller’s larva of polyclads and trochophore larva of polychaetes all resemble one another in structure and ciliary band, this theory considers larvae of acoelomate bilateria (flat worms) as early stages of trochophore.
3. Planuloid-Acoeloid theory
This theory was first proposed by Ludwig von Graff (1882) and later elaborated by L. H. Hyman (1951). The theory postulates that the primitive acoelomate bilateria (helminths) evolved from some planuloid ancestor which was very similar to the planula larva of coelenterates. The planuloid ancestor must have been free-living, radially symmetrical, ciliated and with a diffused nerve net. Such planuloid must have developed into a gastrula-like ancestor by the formation of mouth and archenteron and adopted a bottom creeping mode of living rather than free swimming habit of planula. Creeping habit produced cephalisation of nervous system towards the anterior side and since the food was available at the bottom, the anterior mouth moved to the ventral side and the body became dorso-ventrally flattened, as is the case in turbellarian helminths of today.
yeh waali theories ?
Haan bhai... yahi bol rhe the... yai hona chahiye... theories me
Dang it main yeh naam nahi likhe baaki massala yahi daala hai
Haha.. sahi hai h sahi h...(y). But dekhiyega... avg scores upar honge is baar zoology ke bhi... as accordingly kyuki other optionals were also easy. Btw essay kaun kaun sa likhe?
Last year waala examiner na hua to hoga uppar varna Ram nam satya ho jaye ga.... Essay classrooms wala aur Natural rights waala
Acha sahi h...thoda alag hai... maine farming aur social media... Btw copy checking start ho gyi hai...abi 10-12 din tak days compulsory papers ki chalegi..
Key takeaways... 1. Always complete the syllabus. Anything left will b left forever, and will definitely appear in exam. 2. Make short mini notes of syllabus topics, along with diagrams... to be able to revise in 1.5 day gap before exam. 3.start mugging up, dont leave mugging for exams... car me kar lunga, centre pe jake delh lunga... won't do 4.interlinking of concepts. 5.Sources apart from books- youtube, ncbi, biologydiscussion and your article library. 6. Completing the syllabus initially may take time, but don't worry...subsequent revisions won't be painful. 7. Practicing, upgrading, and revision is a continuous process...
Key takeaways... 1. Always complete the syllabus. Anything left will b left forever, and will definitely appear in exam. 2. Make short mini notes of syllabus topics, along with diagrams... to be able to revise in 1.5 day gap before exam. 3.start mugging up, dont leave mugging for exams... car me kar lunga, centre pe jake delh lunga... won't do 4.interlinking of concepts. 5.Sources apart from books- youtube, ncbi, biologydiscussion and your article library. 6. Completing the syllabus initially may take time, but don't worry...subsequent revisions won't be painful. 7. Practicing, upgrading, and revision is a continuous process...
Looks like there are less people with Zoology Optional.
Let's ask seniors - Guy's what are the takeaways from Mains 2017 Zoology Optional ? Please share your experience. How did it go this time?
Key takeaways... 1. Always complete the syllabus. Anything left will b left forever, and will definitely appear in exam. 2. Make short mini notes of syllabus topics, along with diagrams... to be able to revise in 1.5 day gap before exam. 3.start mugging up, dont leave mugging for exams... car me kar lunga, centre pe jake delh lunga... won't do 4.interlinking of concepts. 5.Sources apart from books- youtube, ncbi, biologydiscussion and your article library. 6. Completing the syllabus initially may take time, but don't worry...subsequent revisions won't be painful. 7. Practicing, upgrading, and revision is a continuous process...
+1 I did not revised only ETC from whole syllabus and it appeared in the paper
Key takeaways... 1. Always complete the syllabus. Anything left will b left forever, and will definitely appear in exam. 2. Make short mini notes of syllabus topics, along with diagrams... to be able to revise in 1.5 day gap before exam. 3.start mugging up, dont leave mugging for exams... car me kar lunga, centre pe jake delh lunga... won't do 4.interlinking of concepts. 5.Sources apart from books- youtube, ncbi, biologydiscussion and your article library. 6. Completing the syllabus initially may take time, but don't worry...subsequent revisions won't be painful. 7. Practicing, upgrading, and revision is a continuous process...
Looks like there are less people with Zoology Optional.
Let's ask seniors - Guy's what are the takeaways from Mains 2017 Zoology Optional ? Please share your experience. How did it go this time?
Key takeaways... 1. Always complete the syllabus. Anything left will b left forever, and will definitely appear in exam. 2. Make short mini notes of syllabus topics, along with diagrams... to be able to revise in 1.5 day gap before exam. 3.start mugging up, dont leave mugging for exams... car me kar lunga, centre pe jake delh lunga... won't do 4.interlinking of concepts. 5.Sources apart from books- youtube, ncbi, biologydiscussion and your article library. 6. Completing the syllabus initially may take time, but don't worry...subsequent revisions won't be painful. 7. Practicing, upgrading, and revision is a continuous process...
+1 I did not revised only ETC from whole syllabus and it appeared in the paper
Lolzz... i left mollusca, bilateral theories, Though i also left insect mouth parts...
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Comments
Btw copy checking start ho gyi hai...abi 10-12 din tak days compulsory papers ki chalegi..
Let's ask seniors - Guy's what are the takeaways from Mains 2017 Zoology Optional ?
Please share your experience. How did it go this time?
@maggie @sapphire♦ @stable_graphene @LBSNAA @dexter_morgan @Supersonic @pizza @Pagalmadmax @Queen @laxmimehra @Geheimnisse @alisha1995 @Jhon siga @chetna29 @mayurmeena @pradeepajit @princemanoj009 @amitshanky @him @Moana_of_Motunui
1. Always complete the syllabus. Anything left will b left forever, and will definitely appear in exam.
2. Make short mini notes of syllabus topics, along with diagrams... to be able to revise in 1.5 day gap before exam.
3.start mugging up, dont leave mugging for exams... car me kar lunga, centre pe jake delh lunga... won't do
4.interlinking of concepts.
5.Sources apart from books- youtube, ncbi, biologydiscussion and your article library.
6. Completing the syllabus initially may take time, but don't worry...subsequent revisions won't be painful.
7. Practicing, upgrading, and revision is a continuous process...
Though i also left insect mouth parts...