Statement I : In sponges, digestion is intracellular and they have canal system.

Statement II : Cnidarians having exoskeleton are able to form islands in sea called coral reefs.

Key Points

• Statement I: Sponges possess a canal system, which helps in water circulation. Water enters through ostia, moves through the spongocoel, and exits via the osculum. Digestion in sponges is intracellular, occurring within specialized cells called choanocytes and amoebocytes.
• Statement II: Cnidarians, particularly corals, secrete calcium carbonate to form an exoskeleton. Over time, coral colonies create massive structures called coral reefs, which can form islands.
• Both statements I and II are scientifically accurate and provide valid information about sponges and cnidarians.

Important Points

• Sponges (Phylum Porifera): They are simple, multicellular animals with a porous body and no true tissues or organs. Their canal system facilitates water flow, aiding in food capture, respiration, and waste removal.
• Intracellular Digestion: This type of digestion occurs inside cells, as seen in sponges. Amoebocytes digest food particles after engulfing them via phagocytosis.
• Coral Reefs: Formed by the accumulation of calcium carbonate exoskeletons of coral polyps over generations. Coral reefs provide habitats for diverse marine life and protect coastlines from erosion.