The discoblastula is found in

Options

A. Echidna/Birds/Reptiles /Fishes
B. Man
C. Branchiostoma
D. Rana.

Answer

To solve the question "The discoblastula is found in", we will follow these steps:

### Step 1: Understand the term "disco blastula"
- The term "disco blastula" refers to a specific type of blastula that is formed during embryonic development. It is characterized by a disc-shaped structure.

### Step 2: Identify the type of eggs associated with discoblastula
- Discoblastula is typically found in organisms that have telolecithal eggs. Telolecithal eggs are those that have a large amount of yolk concentrated at one end, which influences the type of cleavage and embryonic development.

### Step 3: List organisms with telolecithal eggs
- Organisms that exhibit telolecithal eggs include birds, reptiles, echidnas, and certain fish. These organisms show a modified form of blastula known as discoblastula during their embryonic development.

### Step 4: Analyze the options provided
- The options given in the question are:
a. Echidna, birds, reptiles, fishes
b. Man
c. Brachiostoma
d. Rhena
- Based on our understanding, option A includes all the organisms known to have telolecithal eggs and thus discoblastula.

### Step 5: Select the correct answer
- Since discoblastula is found in echidnas, birds, reptiles, and fishes, the correct answer to the question is option A.

### Final Answer:
The discoblastula is found in option A: echidna, birds, reptiles, and fishes.

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