Lecture 6 Flashcards
What is the defining characteristic of Phylum Porifera?
Porifera are “pore-bearing” animals, organized around a system of water canals and chambers
What is the likely ancestral group of sponges?
Phylum Choanoflagellata, single celled eukaryotes similar to sponge choanocytes
What is the ecological importance of sponges?
They serve as microbial symbionts, create habitats for other organisms, and act as filter feeders in aquatic ecosystems
What is the skeletal structure of sponges made from?
Spicules, which provide internal support and protection
Name the five specialized sponge cell types and their functions
- Pinacocytes: thin, contractile epithelial cells covering the exterior
- Porocytes – Tubular cells creating ostia (pores) for water intake.
3.Archaeocytes/Amoebocytes – Totipotent cells involved in digestion, reproduction, and spicule secretion.
- Choanocytes – Flagellated cells that generate water currents and filter food.
- Mesohyl – Gelatinous connective matrix where sponge cells are embedded.
How do sponges feed?
They are filter feeders using choanocytes to trap food particles and archaeocytes to digest them
What are the three types of sponge canal systems?
1) Asconoid – Simplest, water flows through spongocoel and exits via a single osculum.
2) Syconoid – Choanocytes line folded radial canals, increasing surface area for filtration.
3) Leuconoid – Most complex, with choanocyte-lined flagellated chambers and multiple oscula.
What type of reproduction do sponges use?
Both asexual (budding and gemmules) nand sexual reproduction (monoecious, releasing sperm into water)
What is a gemmule?
An overwintering capsule filled with totipotent archaeocytes, used for asexual reproduction
What is the function of parenchymula larvae
They are free-swimming, flagellated sponge larvae that settle and develop into adults
What is the function of spicules in sponges?
Spicules provide structural support and deter predators
How do sponges generate water flow for filter feeding?
Choanocytes use their flagella to create internal water currents, drawing water through ostia and expelling it through the osculum
What is the difference between ostia and osculum?
Ostia are small pores where water enters, while osculum is the large opening where water exits
What are sponges considered protoplasmic organisms?
They lack true tissues and organs, relying instead on specialized cells loosely arranged in a mesohyl matrix
What type of symmetry do sponges have
Most are asymmetrical, though some exhibit radial symmetry
How does a sponge’s body structure influence its size and efficiency?
More complex canal systems (leuconoid) allow for larger body size and more efficient water filtration
What role do archaeocytes play in sponge digestion?
They digest food particles captured by choanocytes and transport nutrients throughout the sponge
What is the main function of pinacocytes?
They form the sponge’s outer layer and contract to slightly alter body shape
How do sponges contribute to aquatic ecosystems?
They filter large volumes of water, remove bacteria and organic debris, and provide habitats for other marine line
What is the evolutionary significance of multicellularity in sponges?
It allows for cell specialization, division of labor, and increased body size, leading to more efficient nutrient absorption and survival
How do sponges regenerate lost body parts?
Totipotent archaeocytes can differentiate into any cell type, enabling regeneration and asexual reproduction
What do sponges lack a nervous system?
Their simple body plan relies on passive water flow rather than active movement or coordinated responses
What are two body forms in Cnidaria?
- Polyp (sessile, asexual)
- Medusa (motile, sexual)
What type of symmetry do Cnidarians have?
Radial symmetry
