Question

Canal system and choanocytes are characteristic of (a) Ctenophora (b) Coelenterates (c) Platyhelminthes (d) Porifera

Short answer

(d) Porifera

Step-by-step solution

Understand the Terms

Learn about the definitions of 'Canal System' and 'Choanocytes'. A canal system is a unique type of water flow system found in certain types of sponges, and Choanocytes are cells that capture food and transport water out of the sponge.

Associate Characteristics with Phylum

Associate these characteristics with the various phyla mentioned in the choices.

Eliminate Incorrect Choices

Eliminate the choices (a) Ctenophora, (b) Coelenterates, and (c) Platyhelminthes since these phyla do not carry the two traits of having both a canal system and Choanocytes.

Confirm Correct Choice

Confirm the remaining choice (d) Porifera, which is the phylum where organisms show the presence of a canal system and Choanocytes.

Key concepts

Canal System

The canal system is a remarkable feature unique to the phylum Porifera, commonly known as sponges. This system plays a critical role in various essential functions such as feeding, respiration, and waste removal. Imagine sponges as having a complex plumbing system made up of a series of interconnected canals. This structure allows the efficient circulation of water throughout the body of the sponge.

The water enters the sponge through tiny openings called ostia. Meticulously designed canals then transport the water to specialized chambers lined with choanocytes, before it exits the sponge through a larger opening called an osculum. This continuous water flow is crucial, as it brings food and oxygen into the sponge and carries away unwanted waste materials.

• The canal system increases surface area for nutrient absorption.
• Canals can vary in complexity, from simple to more intricate systems.
• Efficient for survival in aquatic environments.

Choanocytes

Choanocytes, also known as collar cells, are a defining characteristic of sponges. These unique cells line the inner chambers of the sponge's canal system and play a pivotal role in maintaining the sponge's life functions. Each choanocyte has a flagellum—a whip-like structure—that beats rhythmically.

This motion generates a water current that facilitates the movement of water through the sponge's body. Surrounding the base of the flagellum is a collar-like structure made of microvilli, capturing tiny food particles from the water. The choanocytes not only aid in feeding but also help with gas exchange, ensuring the sponge receives enough oxygen.

• Essential for capturing food and ingesting nutrient particles.
• Help in generating currents to filter water efficiently.
• Aid in reproduction by catching sperm from the water.

Phylum Characteristics

The phylum Porifera is intriguing due to several unique characteristics that set it apart from other phyla. As the most primitive multicellular animals, sponges lack the typical features found in more complex organisms. They do not have true tissues or organs. Instead, they rely on specialized cell types working in harmony.

These fascinating creatures display an incredible ability to adapt to various marine and freshwater environments. Porifera showcases a remarkable cellular level of organization, and its structural simplicity is deceptive given its ecological effectiveness. Key characteristics include:

• Porous body with numerous tiny openings for water flow.
• Presence of a specialized fibrous skeleton made of spongin and/or spicules.
• Can regenerate lost parts, showcasing evolutionary resilience.

Understanding these characteristics is vital to appreciating the complex yet simplistic life of sponges and their crucial role in the aquatic ecosystems they inhabit.