Identify the correct morphological features corresponding to numbers I – IV in the echinoid illustrated below:
Identify the correct morphological features corresponding to numbers I – IV in the echinoid illustrated below:
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- I-Periproct II-Ambulacra III-Interambulacra IV-Peristome
- I-Periproct II-Interambulacra III-Ambulacra IV-Peristome
- I-Peristome II-Interambulacra III-Ambulacra IV-Periproct
- I-Peristome II-Ambulacra III-Interambulacra IV-Periproct
The Correct Option is A
Solution and Explanation
Step 1: Understanding echinoid morphology.
Echinoids are echinoderms (sea urchins) with a specific set of morphological features. These include the periproct (where the anus is located), ambulacra (the areas where tube feet are located), interambulacra (the areas between the ambulacra), and the peristome (the mouth area).
Step 2: Analyzing the options.
(A) I-Periproct II-Ambulacra III-Interambulacra IV-Peristome: This is the correct answer. This matches the typical echinoid morphology, where the periproct is the anus, the ambulacra are the radial areas with tube feet, the interambulacra are the spaces between them, and the peristome is the mouth.
(B) I-Periproct II-Interambulacra III-Ambulacra IV-Peristome: This is incorrect because the positions of the ambulacra and interambulacra are swapped.
(C) I-Peristome II-Interambulacra III-Ambulacra IV-Periproct: This is incorrect because the peristome is not correctly positioned as the mouth.
(D) I-Peristome II-Ambulacra III-Interambulacra IV-Periproct: This is incorrect because the peristome and periproct are swapped.
Step 3: Conclusion.
The correct answer is (A) I-Periproct II-Ambulacra III-Interambulacra IV-Peristome because this accurately reflects the positions of the features in an echinoid.
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