Problem 3 - Campbell Biology

Question

The water vascular system of echinoderms \begin{equation}\begin{array}{l}{\text { (A) functions as a circulatory system that distributes nutrients }} \\ {\text { to body cells. }} \\ {\text { (B) functions in locomotion and feeding. }} \\ {\text { (C) is bilateral in organization, even though the adult animal }} \\ {\text { is not bilaterally symmetrical. }} \\ {\text { (D) moves water through the animal's body during filter feeding. }}\end{array}\end{equation}

Step-by-Step Solution

Answer

The water vascular system functions in locomotion and feeding.

Step 1 - Understanding the Water Vascular System

First, identify what the water vascular system of echinoderms is. It is a network of hydraulic canals unique to echinoderms such as starfish, sea urchins, and sand dollars.

Step 2 - Determine the Functions

Research and understand the primary functions of the water vascular system. It is mainly involved in locomotion, feeding, and respiration.

Step 3 - Evaluate Each Option

Now, evaluate each option in the context of what the water vascular system actually does:(A) Incorrect - The system is not primarily for distributing nutrients.(B) Correct - The water vascular system is indeed involved in locomotion and feeding.(C) Incorrect - The system does not relate to bilateral organization.(D) Incorrect - It does not primarily serve the purpose of moving water for filter feeding.

Step 4 - Select the Correct Answer

Based on the evaluation, the correct answer is option (B). The water vascular system functions in locomotion and feeding.

Key Concepts

echinoderm locomotion

Echinoderms move in a fascinating and unique way compared to other animals. Their movement relies heavily on their water vascular system. This system consists of a network of hydraulic canals filled with seawater. To move, echinoderms like starfish use tiny tube feet located on the underside of their arms. These tube feet function through a process called hydraulic pressure. When the echinoderm wants to extend a tube foot, it pumps water into the foot, causing it to elongate. To retract the foot, the water is withdrawn. This coordinated movement of hundreds of tube feet enables the echinoderm to creep along surfaces. This method of locomotion allows them to navigate across the ocean floor with precision and flexibility.

feeding mechanisms in echinoderms

Feeding mechanisms in echinoderms are as unique as their locomotion. Echinoderms have adapted various ways to feed, depending on their species. For example, starfish often feed on bivalve mollusks such as clams and oysters. They use their tube feet to pry open the shells of their prey. Once they've managed to open the shell enough, they extend their stomachs out of their mouths and into the shell to digest the mollusk. Sea urchins, on the other hand, use a jaw-like structure called Aristotle’s lantern to scrape algae off rocks. Brittle stars utilize their flexible arms to capture food particles suspended in the water. Despite differences in their feeding strategies, the water vascular system plays a critical role in enabling these activities, whether it's extending tube feet or manipulating their mouths for feeding.

unique hydraulic systems in marine animals

The water vascular system is a remarkable hydraulic mechanism unique to echinoderms. Unlike any other group of animals, echinoderms use the seawater that surrounds them to power their movement and feeding. This system includes components such as the madreporite, a sievelike structure on the surface of the body. Water enters the vascular system through the madreporite, travels down the stone canal, and reaches the ring canal encircling the gut. From the ring canal, radial canals extend into each arm where they branch into lateral canals leading to the tube feet. The hydraulic system works by changing water pressure within these canals to extend or contract the tube feet. This unique adaptation not only assists in locomotion and feeding but also in sensory reception and respiration. By harnessing the power of hydraulics, echinoderms have adapted to thrive in their marine environments in ways that set them apart from other animals.