Question

Identify the schizocoelomate phyla from the following.
I. Platyhelminthes
II. Nematoda
III. Annelida
IV. Chordata
V. Arthropoda
VI. Echinodermata
VII. Mollusca

• A. II, III, IV
• B. III, V, VII
• C. IV, VI
• D. I, II

Hint:

To remember coelom types: \begin{itemize} \item \textbf{Acoelomates:} Platyhelminthes (Flatworms - A for Absent coelom). \item \textbf{Pseudocoelomates:} Nematoda (Roundworms - Pseudo-coelom). \item \textbf{True Coelomates:} \begin{itemize} \item \textbf{Schizocoelomates (Protostomes):} Coelom from splitting mesoderm. Examples: Annelida, Arthropoda, Mollusca (A-A-M). \item \textbf{Enterocoelomates (Deuterostomes):} Coelom from gut pouches. Examples: Echinodermata, Chordata (E-C). \end{itemize} \end{itemize}

Answer 1

The Correct Option is B

Step 1: Understand Coelom Types
The coelom (body cavity) is a fluid-filled space between the digestive tract and the outer body wall. Its development varies among different animal phyla.
There are broadly three types based on the presence and origin of the coelom: \begin{itemize} \item Acoelomates: Animals without a body cavity (e.g., Platyhelminthes). \item Pseudocoelomates: Animals with a body cavity that is not lined by mesoderm (e.g., Nematoda). \item Coelomates (Eucoelomates): Animals with a true coelom, which is a body cavity lined by mesoderm. Coelomates are further divided based on the origin of the coelom: \begin{itemize} \item Schizocoelomates: The coelom arises from the splitting of the mesoderm. These are typically protostomes. Examples include Annelida, Arthropoda, and Mollusca. \item Enterocoelomates: The coelom arises from pouches of the archenteron (embryonic gut). These are typically deuterostomes. Examples include Echinodermata and Chordata. \end{itemize} \end{itemize} Step 2: Classify each given phylum based on coelom type
Let's go through each phylum in the list:
\ I. Platyhelminthes (Flatworms): These are acoelomates (no true body cavity).
II. Nematoda (Roundworms): These are pseudocoelomates.
III. Annelida (Segmented worms): These are schizocoelomates.
IV. Chordata (Vertebrates and related): These are enterocoelomates.
V. Arthropoda (Insects, crustaceans, spiders): These are schizocoelomates.
VI. Echinodermata (Starfish, sea urchins): These are enterocoelomates.
VII. Mollusca (Snails, clams, octopuses): These are schizocoelomates. Step 3: Identify the schizocoelomate phyla
Based on the classification in Step 2, the schizocoelomate phyla are:
III. Annelida
V. Arthropoda
VII. Mollusca
Step 4: Choose the correct option The option that includes only III, V, and VII is (2).