PLATYHELMINTHES
Examples: Tapeworm, flatworms, and planarians.
There are approximately 20,000 species of the phylum, Platyhelminthes. Now, you might be a bit confused and must be thinking what a Flatworm is. Well, let me explain, a Flatworm is a various type worm which is a part of the Platyhelminthes phylum, and includes worms such as: parasitic tapeworms and flukes, that are composed of flat, soft, and perfectly symmetric bodies. The species that are part of this phylum range from tremendously colored creatures that are located in the ocean and swim to the parasitic flatworms that live inside of, approximately, 200 million human bodies. These Flatworm creatures are hermaphroditic, which simply means that they have both male and female reproductive organs, and that they are able to produce both sexually and asexually. Now, the creatures of the Platyhelminthes phylum do not contain a body cavity nor a circulatory system. The circulatory system is very crucial for many organisms, but the species in this phylum do no have this specific system.
There are approximately 20,000 species of the phylum, Platyhelminthes. Now, you might be a bit confused and must be thinking what a Flatworm is. Well, let me explain, a Flatworm is a various type worm which is a part of the Platyhelminthes phylum, and includes worms such as: parasitic tapeworms and flukes, that are composed of flat, soft, and perfectly symmetric bodies. The species that are part of this phylum range from tremendously colored creatures that are located in the ocean and swim to the parasitic flatworms that live inside of, approximately, 200 million human bodies. These Flatworm creatures are hermaphroditic, which simply means that they have both male and female reproductive organs, and that they are able to produce both sexually and asexually. Now, the creatures of the Platyhelminthes phylum do not contain a body cavity nor a circulatory system. The circulatory system is very crucial for many organisms, but the species in this phylum do no have this specific system.
CIRCULATORY SYSTEM
Specific animals that are part of this phylum are: Tapeworms, Flatworms, and also Planarians. So, these worm-like creatures are part of this phylum and do not contain a circulatory system. Now, just a brief overview of the sytem. The circulatory system is an organ system which transports crucial nutrients, blood cells, and also gases to form new cells throughout the body. This system is composed of three specific parts (refer to home page) and each part plays a cruial role for the body. Because these animals do not obtain a circulatory system, their body passes oxygen and certain nutrients through diffusion (specific particles moving from high concentrations to lower concentrations). As you will learn, most creatures in this phylum that do not have a circulatory system will transport essential nutrients, gases, and oxygen through diffusion!