Question

phylum annelida
leeches, like the ones shown above, make up this class of annelids. they produce hirudin, which is an anti - clotting substance often used for medicinal uses. they are mostly free living carnivores.
what are the features of the class oligochaeta?
paddle - like appendages, can live in tubes, and live in marine or aquatic habitats
contains leeches, some have medicinal uses, most are free - living carnivores
mostly earthworms, repeated body segments, and a closed circulatory system

Explanation:

• Analyze Option 1: Paddle - like appendages (parapodia), tube - dwelling, marine/aquatic are features of Class Polychaeta, not Oligochaeta.
• Analyze Option 2: Leeches belong to Class Hirudinea, not Oligochaeta.
• Analyze Option 3: Class Oligochaeta is dominated by earthworms, has metameric (repeated) body segmentation, and a closed circulatory system, matching the characteristics of this class.

Answer:

C. mostly earthworms, repeated body segments, and a closed circulatory system (assuming the options are labeled A, B, C with A being the first, B the second, C the third; the third option is correct as Class Oligochaeta includes earthworms, has segmented bodies, and a closed circulatory system. The first option describes Polychaeta, the second describes Hirudinea (leeches))