Chapter 27, Problem 8A

Summary Introduction

Introduction:

Echinoderms (scientific name Echinodermata) are a significant gathering of just marine creatures. The name originates from the Greek word for "spiked skin". There are around 7,000 species found ordinarily on the ocean bottom in each marine environment from the intertidal zone to the sea profundities. They have a wide variety of hues.

Answer to Problem 8A

Correct answer:

The correct answer is option (c) Larvae have bilateral symmetry and adults have radial symmetry.

Explanation of Solution

Explanation/justification for the correct answer:

Option (C) Larvae have bilateral symmetry and adults have radial symmetry.

Mostly all the animals are of bilateral symmetry except the ones having radial symmetry. But in the Echinodermata phylum which includes animals like sea stars, sea urchins show the radial symmetry as an adult but the larvae stage shows bilateral symmetry, They are also known as Secondary radial symmetry.

Explanation for incorrect answer:

Option (a) Larvae are protosomes and adults are deuterostomes.

The larva cannot be protosomes as it includes arthropods, annelids and mollusks. So, this answer is incorrect.

Option (b) Larvae are deuterostomes and adults are .protosomes.

As Deuterostomes include the vertebrates, echinoderm, and chordata as it helps the blastopore to develop into an anus. But the adults are not protosomes as it includes arthropods, annelids and mollusks. So, this answer is incorrect.

Option (d) Larvae have radial symmetry and adults have bilateral symmetry.

In the Echinodermata phylum, animals show the radial symmetry as an adult but the larvae stage shows bilateral symmetry. So, this is an incorrect answer.

Conclusion

The main difference between Larvae and Adults is Larvae have bilateral symmetry and adults have radial symmetry.

Hence, the correct answer is option (C) genes.