Question

Heteronereis is
A. Member of Hirudinaria
B. Freshwater annelid
C. Sexual phase of Nereis
D. Sanguivorous animal

Answer 1

Hint: Heteronereis is a type of worm that belongs to the phylum Annelida. The presence of several segments on the body is a very unique feature found in all annelids. Each of the segments has a pair of locomotive structures. It is the dimorphic form of the Nereis.

Complete answer: Nereis is a genus of polychaete worms in the Nereididae family. It consists of several animals, most of which are marine. Nereis has setae and locomotive parapodia. They may have two forms of setae found on parapodia. Acicular setae shall provide assistance. The locomotive chaetae are for crawling, and the bristles are visible on the exterior of the Polychaeta. They are cylindrical in shape. They are found in sandy areas and are suited to the burrow.
A free-swimming dimorphic sexual organism of some polychaete species (coming from family Nereidae) with substantially enlarged eyes, enhanced and altered parapodia and other appendages, and otherwise complete disintegration of parapodia and other appendages. Externally, both male and female individuals have a distinction between modified posterior and unmodified anterior, therefore, which is a characteristic feature of Nereis. Nereis is the sexually immature stage of the phylum Annelida. Heteronereis is the dimorphic sexual form of Nereis.
So, the correct response is C-'Sexual phase of Nereis.'

Note: Nereis has an outstanding attribute that it retains its internal environment, which is equal in focus to its surroundings. The pressure inside the cells of the body and the pressure of the surroundings are both equivalent. These species are referred to as osmoconformers.