An undifferentiated mass of animal cells that later forms a structure or organ either embryologically if through regeneration, for example the head of a flatworm. A blind ending sac of the digestive system located between the large and small intestine. A short cellular appendage specialized for locomotion. An organelle that pumps excess water out of many freshwater protist cells. An occurance of an organism in two forms.
Sexual dimorphism refers to males and females.
Dimorphism may occur in, for example, body form or colour. The tubular passage that extends from mouth to anus. A cell specialized for excretion found in platyhelminths. It appears to have mainly vegetative functions. The middle primary germ layer of an early embryo that develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system.