NEMATODA
Examples: Roundworms, threadworms and eelworms
The Nematoda phylum refers to the phylum which is mainly composed of animals or creatures known as: Roundworms, or more commonly known as Nematodes. Both the Platyhelminthes phylum and the Nematoda phylum have many similarities and correlate quite a bit due to the species they both pertain to. In this phylum, nematodes make up most of the population. Nematodes are worm-like creatures that are surrounded by an exterior layer of strong, flexible, and a non-cellular cuticle. The body of these organisms are very similar to the bodies of the creatures in the Platyhelminthes phylum. Nematodes are bilaterally symmetrical, and have flat and simple bodies. Nematodes are known to be very free-living and spread out throughout various areas. For example, studies have shown that nematodes are found to be in rotten apples (90,000 nematodes per apple), mud, and also spread throughout wide areas and habitats. Once again, Nematodes and/or any other species in this phylum do not contain a circulatory system.
The Nematoda phylum refers to the phylum which is mainly composed of animals or creatures known as: Roundworms, or more commonly known as Nematodes. Both the Platyhelminthes phylum and the Nematoda phylum have many similarities and correlate quite a bit due to the species they both pertain to. In this phylum, nematodes make up most of the population. Nematodes are worm-like creatures that are surrounded by an exterior layer of strong, flexible, and a non-cellular cuticle. The body of these organisms are very similar to the bodies of the creatures in the Platyhelminthes phylum. Nematodes are bilaterally symmetrical, and have flat and simple bodies. Nematodes are known to be very free-living and spread out throughout various areas. For example, studies have shown that nematodes are found to be in rotten apples (90,000 nematodes per apple), mud, and also spread throughout wide areas and habitats. Once again, Nematodes and/or any other species in this phylum do not contain a circulatory system.
CIRCULATORY SYSTEM
Now, a body cavity is: the space between the epidermis of an organism and the outer layer of the "gut cavity." Because thee species are copiously reproductive (reproduce abundantly) there body cavity is composed of different sets of organs. The Nematodes do not obtain a circulatory system and are able to transfer the oxygen and the necessary nutrients for themselves by diffusion. Once again, this sounds very similar to what the creatures in the Platyhelminthes phylum do, this is because, each phylum listed evolves after a certain period of time into the next phylum!** So, nematodes are simply organisms that appear as parasites, which occur in all sorts of plants and animals; but these nematodes are not fond of dry areas. The number of this organism varies, but scientists believe that there are millions of these species around the globe. The circulatory system is obviously not present in the organisms in this phylum, therefore, the species in this phylum obtain a pseudocoelom, which is basically the body cavity of any multicellular organism filled with superfluous amount of fluids, and also transports the specific nutrients, oxygen, etc. So, because there is an absent of the circulatory system, the metabolic waste is excreted by two ducts that the species have. This phylum also includes animals such as: roundworms, gastrotrichs, and also trichina worms.