Phylum Porifera - NOTES and MCQs

Table of Contents

• Phylum – Porifera
• Characteristics of Phylum Porifera
• Water Transport System
• Reproduction in Porifera
• FAQs
• MCQs

Phylum – Porifera

Members of this phylum are commonly known as sponges. They are generally marine and mostly asymmetrical animals. Sponges are primitive multicellular animals with a cellular level of organization.

Characteristics of Phylum Porifera

Sponges have several distinct characteristics:

• Habitat: Mostly marine
• Symmetry: Mostly asymmetrical
• Organization: Cellular level
• Skeleton: Made up of spicules or spongin fibers
• Sexes: Hermaphrodite (eggs and sperms are produced by the same individual)

Water Transport System

Sponges possess a unique water transport or canal system:

• Ostia: Minute pores through which water enters
• Spongocoel: Central cavity where water is collected
• Osculum: Opening through which water exits
• Choanocytes: Also known as collar cells, they line the spongocoel and canals

This water pathway aids in food gathering, respiratory exchange, and waste removal. Digestion is intracellular.

Reproduction in Porifera

Sponges can reproduce both asexually and sexually:

• Asexual Reproduction: By fragmentation
• Sexual Reproduction: By formation of gametes

Fertilization is internal, and development is indirect with a larval stage that is morphologically distinct from the adult.

FAQs

Q: What are sponges?
A: Sponges are primitive multicellular animals belonging to the phylum Porifera. They are mostly marine and asymmetrical.

Q: How do sponges reproduce?
A: Sponges reproduce both asexually by fragmentation and sexually by forming gametes. Fertilization is internal, and development includes a distinct larval stage.

Q: What is the water transport system in sponges?
A: The water transport system in sponges involves water entering through ostia, moving into the spongocoel, and exiting through the osculum. This system helps in food gathering, respiratory exchange, and waste removal.

Q: What supports the body of a sponge?
A: The body of a sponge is supported by a skeleton made up of spicules or spongin fibers.

Q: What are choanocytes?
A: Choanocytes, or collar cells, line the spongocoel and canals in sponges. They play a role in the water transport system and aid in digestion.

MCQs

1. What is the common name for members of the phylum Porifera?
   1. Jellyfish
   2. Corals
   3. Sponges
   4. Sea anemones

   Answer: C. Sponges

2. Where does water enter a sponge?
   1. Osculum
   2. Spongocoel
   3. Ostia
   4. Choanocytes

   Answer: C. Ostia

3. What supports the body of a sponge?
   1. Cartilage
   2. Spicules or spongin fibers
   3. Chitin
   4. Calcium carbonate

   Answer: B. Spicules or spongin fibers

4. How do sponges reproduce asexually?
   1. By budding
   2. By fission
   3. By fragmentation
   4. By parthenogenesis

   Answer: C. By fragmentation

5. What type of cells line the spongocoel and canals in sponges?
   1. Collar cells
   2. Amoebocytes
   3. Pinacocytes
   4. Mesenchyme cells

   Answer: A. Collar cells

6. What is the central cavity of a sponge called?
   1. Osculum
   2. Gastrovascular cavity
   3. Spongocoel
   4. Coelom

   Answer: C. Spongocoel

7. What is the term for organisms that have both male and female reproductive organs?
   1. Dioecious
   2. Monoecious
   3. Hermaphrodite
   4. Bisexual

   Answer: C. Hermaphrodite

8. Which of the following is a freshwater sponge?
   1. Sycon
   2. Spongilla
   3. Euspongia
   4. All of the above

   Answer: B. Spongilla

9. What is the process of internal fertilization in sponges followed by?
   1. Direct development
   2. Indirect development
   3. Parthenogenesis
   4. External fertilization

   Answer: B. Indirect development

10. Which structure in sponges is responsible for the removal of waste?
    1. Ostia
    2. Osculum
    3. Spongocoel
    4. Choanocytes

    Answer: B. Osculum

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