Question

what are the only fully formed organs on cnidarians?
○ endocrine organs
○ sexual organs
○ digestive organs
○ circulatory organs

question 20
1 pts
what is a type of aquatic segmented worm with two sets of two eyes, multiple antennae, and small appendages that aid in feeding and sensing?
○ marine worms
○ round worms
○ flatworms
○ earthworms

Explanation:

First Question (About Cnidarians' Organs)

Cnidarians (like jellyfish, corals) have a gastrovascular cavity that functions as a digestive organ. They lack complex endocrine, circulatory, or fully - formed sexual organs in the way other more complex organisms do. So the only fully formed organs in cnidarians are digestive organs.

• Marine worms are aquatic, segmented, and can have the described features (two sets of two eyes, multiple antennae, small appendages for feeding/sensing).
• Round worms (nematodes) are unsegmented.
• Flatworms (platyhelminthes) are unsegmented.
• Earthworms are terrestrial (though some are aquatic, but they don't have the described eye/antennae features). So the correct answer is marine worms.

Answer:

C. digestive organs

Second Question (About Aquatic Segmented Worm)