Ascidian

Ascidians (Ascidia) begin their lives as larvae, just a few millimeters long, living freely in the ocean and resembling tadpoles. After completing their larval stage, they undergo metamorphosis to become adults. This metamorphosis process is complex, taking several days to complete. The body of an adult, which lives a sedentary lifestyle, is covered by a tough outer layer called a tunic. The branchial orifice leads to a pharynx that occupies over half of the body’s volume and is perforated by thousands of tiny slits. These slits trap microscopic food particles, which are coated in mucus and moved by cilia toward the mouth. The digestive system then extends through the esophagus, stomach and intestines. Ascidians have a heart and veins, with each blood circulation cycle taking several minutes. Each individual has both male and female reproductive organs. However, self-fertilization does not occur because male reproductive cells mature and are released before the female eggs. Some colonial species of ascidians can also reproduce asexually through budding. Ascidians are exclusively marine organisms, and many species are brightly colored in hues of yellow, red, blue or purple.