Animal Stinging Capsules: Location Explained

The question asks about the specific location of stinging capsules, also known as nematocysts or cnidocytes, in certain animals. These specialized cells are characteristic features of animals belonging to the phylum Cnidaria. They are primarily used for capturing prey and for defense.

Let's analyze the options provided to determine which animal fits the description of having stinging capsules located around the mouth and on the tentacles:

Analyzing Animal Options

• Taenia: This organism is a type of tapeworm, belonging to the phylum Platyhelminthes. Tapeworms are parasitic flatworms and do not possess stinging cells (nematocysts). Their mode of nutrient absorption is entirely different.
• Nereis: This is a marine annelid worm, belonging to the phylum Annelida. Annelids, like earthworms and leeches, do not have nematocysts. They have segmented bodies and different structures for feeding and locomotion.
• Adamsia: This is a genus of sea anemones. Sea anemones are well-known members of the phylum Cnidaria. A defining characteristic of cnidarians is the presence of stinging cells (nematocysts) housed within specialized cells called cnidocytes. In sea anemones like Adamsia, these stinging cells are abundantly found on their tentacles, which they use to sting and capture prey. They are also often concentrated around the oral disc, near the mouth, aiding in manipulating food. This matches the description given in the question.
• Ascaris: This organism is a type of roundworm, belonging to the phylum Nematoda. Roundworms are unsegmented worms and lack stinging cells. They have a complete digestive system but do not utilize nematocysts.

Conclusion on Stinging Capsule Location

Based on the analysis, Adamsia, being a sea anemone (a Cnidarian), is the animal where stinging capsules (nematocysts) are characteristically found around the mouth and on the tentacles. These structures are crucial for its predatory lifestyle.