Leeches are parasitic because they suck blood not giving any benifit but harm.
Segmented digestive system, appendages are animal characteristics.
Animals are a major group of organisms, classified as the kingdom Animalia or metozoa. Animals have several characteristics that set them apart from other living things. They are all eukaryotic and usually multicellular, which separates them from bacteria and most protists. Different animals differ in their own characteristics such as appendages, segmentation among other animal characteristics.
Answer:
the cause of variation are
- mutation
- random fertilization
- recombination between homologous chromosome
hope it helps.
