Hexactinellida MCQs December 4, 2025September 30, 2024 by u930973931_answers 30 min Score: 0 Attempted: 0/30 Subscribe 1. What is the primary characteristic of sponges in the class Hexactinellida? (A) They have organic spicules. (B) They have calcium carbonate spicules. (C) They lack spicules. (D) They have siliceous spicules. 2. Hexactinellida sponges are commonly known as: (A) Marine sponges (B) Stone sponges (C) Glass sponges (D) Freshwater sponges 3. Which type of body plan is predominantly found in Hexactinellida sponges? (A) Asconoid (B) Syconoid (C) Both A and B (D) Leuconoid 4. What type of spicules do Hexactinellida sponges possess? (A) Siliceous spicules with a hexactinal structure (B) Calcitic spicules (C) Organic spicules (D) All of the above 5. Where are Hexactinellida sponges primarily found? (A) Freshwater habitats (B) Deep marine environments (C) Terrestrial environments (D) Intertidal zones 6. Which of the following is a common characteristic of Hexactinellida sponges? (A) They have a soft, jelly-like texture. (B) They can be found in both freshwater and marine environments. (C) They are exclusively colonial. (D) They exhibit a high degree of structural complexity. 7. Hexactinellida sponges typically reproduce through which method? (A) Asexual reproduction only (B) Sexual reproduction only (C) Both asexual and sexual reproduction (D) Budding only 8. What is the ecological role of Hexactinellida sponges in marine environments? (A) Primary producers (B) Filter feeders (C) Predators (D) Decomposers 9. Hexactinellida sponges are characterized by their: (A) High metabolic rates (B) Thick walls (C) Simple body structure (D) Unique hexactinal spicules 10. Which structure is essential for water circulation in Hexactinellida sponges? (A) Osculum (B) Choanocytes (C) Spongocoel (D) All of the above 11. What type of symmetry do Hexactinellida sponges exhibit? (A) Bilateral symmetry (B) Radial symmetry (C) Asymmetry (D) None of the above 12. Which of the following is a genus of sponges in the class Hexactinellida? (A) Clathrina (B) Euplectella (C) Oscillatoria (D) Chlamydomonas 13. What larval stage do Hexactinellida sponges undergo? (A) Planula (B) Parenchymella (C) Trochophore (D) Veliger 14. What is a common feature of the habitat where Hexactinellida sponges are found? (A) Shallow waters (B) High current areas (C) Coral reefs (D) Deep ocean floors 15. Which best describes the physical structure of Hexactinellida sponges? (A) Rigid and glassy (B) Gelatinous and soft (C) Flexible and leathery (D) Hard and calcareous 16. In terms of biodiversity, Hexactinellida sponges are considered to be: (A) Highly diverse (B) Low diversity (C) Moderately diverse (D) Non-diverse 17. What type of feeding mechanism do Hexactinellida sponges utilize? (A) Absorption (B) Photosynthesis (C) Filter feeding (D) Predation 18. What is the primary mode of locomotion for Hexactinellida sponges? (A) They are sessile (non-moving). (B) Crawling (C) Swimming (D) Burrowing 19. Which feature differentiates Hexactinellida from other sponge classes? (A) Presence of unique hexactinal spicules (B) Presence of calcium carbonate spicules (C) Presence of siliceous spicules (D) Presence of a soft body 20. Hexactinellida sponges are often found at what depths? (A) Less than 10 meters (B) 10 to 100 meters (C) Greater than 1000 meters (D) 100 to 1000 meters 21. What is the primary threat to Hexactinellida sponges in their natural habitat? (A) Pollution (B) All of the above (C) Habitat destruction (D) Overfishing 22. What kind of skeleton do Hexactinellida sponges have? (A) Calcareous skeleton (B) No skeleton (C) Organic skeleton (D) Siliceous skeleton 23. Hexactinellida sponges are primarily composed of which type of cells? (A) Epithelial cells (B) Nerve cells (C) Choanocytes (D) Muscle cells 24. Which of the following is NOT a characteristic of Hexactinellida sponges? (A) Siliceous spicules (B) Ability to photosynthesize (C) Complex canal systems (D) Presence of oscula 25. What is the role of the mesohyl in Hexactinellida sponges? (A) Nutrient transport and structural support (B) Water circulation (C) Gas exchange (D) All of the above 26. Hexactinellida sponges are known for their: (A) Long lifespan (B) Rapid growth (C) Bright coloration (D) Ability to regenerate quickly 27. What unique feature allows Hexactinellida sponges to filter water efficiently? (A) Large size (B) Complex canal system (C) High reproductive rate (D) None of the above 28. Which ecological role do Hexactinellida sponges fulfill? (A) Filter feeders and habitat providers (B) Secondary producers (C) Decomposers (D) Primary consumers 29. Hexactinellida sponges can be found in which marine environments? (A) Coral reefs (B) Coastal lagoons (C) Intertidal zones (D) Deep-sea habitats 30. Which of the following is a significant aspect of the biology of Hexactinellida sponges? (A) They are strictly freshwater species. (B) They possess true tissues. (C) They have a unique reproductive cycle. (D) They can survive in extreme temperatures.