Which phylum includes animals that lack true tissues?

• A. Platyhelminthes
• B. Annelida
• C. Cnidaria
• D. Porifera

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of 'true tissues.' True tissues are organized groups of cells that work together to perform specific functions, and they are a characteristic of more complex animals.
2. Step 2: Review the characteristics of the phylum Porifera. Porifera, commonly known as sponges, are simple animals that lack true tissues and organs. Their bodies are composed of loosely organized cells.
3. Step 3: Compare Porifera with the other phyla listed in the problem. Platyhelminthes, Annelida, and Cnidaria all possess true tissues, making them more complex than Porifera.
4. Step 4: Understand why Porifera is the correct answer. Sponges are unique among animals because they rely on specialized cells rather than organized tissues to perform functions like feeding and reproduction.
5. Step 5: Conclude that Porifera is the phylum that includes animals lacking true tissues, based on their structural simplicity and cellular organization.