Among the following sanguivorous (blood sucking) is

Sanguivorous organisms are those that feed exclusively or primarily on blood. The term is derived from the Latin 'sanguis' (blood) and 'vorare' (to devour) [t1][t2]. Leeches (Hirudinea) are well-known examples of sanguivorous parasites that use specialized suckers and bioactive chemicals in their saliva, such as anticoagulants (hirudin) and anesthetics, to feed on the blood of vertebrate hosts without being detected [t3][t4][t5]. In contrast, earthworms are typically detritivores that feed on organic matter in soil [t6]. Nereis is a genus of polychaete worms that are generally predatory or scavengers in marine environments [t6]. Ascaris is an endoparasite that lives in the human intestine and derives nutrition from digested food rather than blood [c2]. Therefore, among the given options, only the leech is classified as sanguivorous [c4][t1].

Sources

1. [1] https://www.sciencedirect.com/topics/immunology-and-microbiology/sanguivore
2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 3: Health: The Ultimate Treasure > Activity 3.4: Let us find out > p. 35
3. [3] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > 5.2.2 Heterotrophic Nutrition > p. 84