Phylum Platyhelminthes
Platyhelminthes can be found on ocean floors or as parasites inside organisms. They are among the oldest multicellular organisms in the world, and some of the most simplest. They include tapeworms and flatworms, and they do not have a proper circulatory system. Because of their generally flat shapes, oxygen, nutrients, and wastes can be easily diffused through their body cells surrounded by water. Since molecules can easily be diffused throughout the bodies of Platyhelminthes, there is no need for a circulatory system.
Girardia Tigrina
Around 1 mm in length, this planarian originates in America but has also been introduced into Japan and Europe. It's miniscule size contributes to its ability for diffusion in order to obtain nutrients and exchange gases. It receives oxygen and releases carbon dioxide through diffusion, so it does not have a circulatory system.
Around 1 mm in length, this planarian originates in America but has also been introduced into Japan and Europe. It's miniscule size contributes to its ability for diffusion in order to obtain nutrients and exchange gases. It receives oxygen and releases carbon dioxide through diffusion, so it does not have a circulatory system.
Taenia Asiatica
Found in many East Asian countries and known as the Asian Tapeworm, it is a parasitic tapeworm that has primary hosts of humans, but sometimes live inside pigs and cattle as well. They live inside visceral organs, such as the liver and small intestine, of its host. The intestine, and other organs it can inhabit, is full of food particles and nutrients essential to its diet. It lacks a circulatory system because it directly intakes oxygen and nutrients through diffusion in its body walls.
Found in many East Asian countries and known as the Asian Tapeworm, it is a parasitic tapeworm that has primary hosts of humans, but sometimes live inside pigs and cattle as well. They live inside visceral organs, such as the liver and small intestine, of its host. The intestine, and other organs it can inhabit, is full of food particles and nutrients essential to its diet. It lacks a circulatory system because it directly intakes oxygen and nutrients through diffusion in its body walls.
Cycloporus Venetus
Around 2 cm. in length, the Blue Flatworm can be found underwater in the marine habitats of Australia, Malaysia, and Southeast Asia. Since their bodies are flat, nutrients, oxygen, and wastes easily diffuse through its body cells. Like other platyhelminthes, there is no circulatory system.
Around 2 cm. in length, the Blue Flatworm can be found underwater in the marine habitats of Australia, Malaysia, and Southeast Asia. Since their bodies are flat, nutrients, oxygen, and wastes easily diffuse through its body cells. Like other platyhelminthes, there is no circulatory system.