CATDOLL : CATDOLL: Classification of lugworms, leeches, hydras, and centipedes

Nereids, leeches, hydras, and centipedes all belong to multilocular animals, and their classification and differences are as follows:

Hydra is a coelenterate in the lower animal genus, and is the most primitive multicellular animal at the cellular level. It reproduces by budding and regeneration. It lives in fresh water, in clear water or ponds with slow currents and abundant aquatic plants, especially in clean ponds with little disturbance. Its body is tubular, with a closed end called the pedal disk, on which there are glandular cells that can secrete mucus, and through which it attaches to aquatic plants or other objects.

Nereids and leeches are annelids in the genus of higher invertebrates, with the following main characteristics: (i) segmented body, (ii) occurrence of true body cavity, (iii) closed circulatory system, (iv) excretory system, and (v) nervous system. Nereids are typical marine annelids, with tubercles and bristles, responsible for locomotion and respiration, and are polychaetes in the phylum Annelida; leeches, commonly known as leeches, are representative animals of the class Polychaetes in the phylum Annelida, most of which are aquatic, and a few are terrestrial. They have no tubercles and generally no bristles; the number of body segments is constant.

Centipedes are arthropods in the genus of higher invertebrates.