Question

Which of the following is/are true about polychaete worms?

A. They typically live in a marine environment.

B. They are ecdysozoans.

C. They have a water vascular system.

D. They are unsegmented bilaterians.

E. They feed by using nematocysts.

Answer 1

Polychaete worms are marine, segmented protostomes within the phylum Annelida and the class Polychaeta. They do not have a water vascular system or use nematocysts for feeding, differentiating them from echinoderms and cnidarians respectively.

Step-by-step explanation:

Regarding polychaete worms, it's true that they typically live in a marine environment, as the majority are found on the ocean floor and in various marine habitats. Polychaetes have well-developed nervous and digestive systems, are segmented, and their segments are externally and internally divided by septa. They are protostomes and belong to the phylum Annelida, specifically within the class Polychaeta, characterised by the presence of parapodia and chaetae. They are not ecdysozoans like nematodes and arthropods, which go through a process of molting. Polychaetes do not have a water vascular system, which is a characteristic of echinoderms, not annelids. Furthermore, unlike cnidarians which feed using nematocysts, a special cell for delivering toxins to prey and predators, polychaete worms have various feeding mechanisms, none of which involve nematocysts.