Title: Phylum Nematoda | Biology for Majors II
Headings: Phylum Nematoda
Phylum Nematoda
Learning Outcomes
Morphology
Excretory System
Nervous System
Reproduction
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Content: Phylum Nematoda | Biology for Majors II
Phylum Nematoda
Learning Outcomes
Describe the features of animals classified in phylum Nematoda
The Nematoda, like most other animal phyla, are triploblastic and possess an embryonic mesoderm that is sandwiched between the ectoderm and endoderm. They are also bilaterally symmetrical, meaning that a longitudinal section will divide them into right and left sides that are symmetrical. Furthermore, the nematodes, or roundworms, possess a pseudocoelom and consist of both free-living and parasitic forms. It has been said that were all the non-nematode matter of the biosphere removed, there would remain a shadow of the former world in the form of nematodes. [ 1] The arthropods, one of the most successful taxonomic groups on the planet, are coelomate organisms characterized by a hard exoskeleton and jointed appendages. Both the nematodes and arthropods belong to the superphylum Ecdysozoa that is believed to be a clade consisting of all evolutionary descendants from one common ancestor. The name derives from the word ecdysis, which refers to the shedding, or molting, of the exoskeleton. The phyla in this group have a hard cuticle that covers their bodies, which must be periodically shed and replaced for them to increase in size. Phylum Nematoda includes more than 28,000 species with an estimated 16,000 being parasitic in nature. The name Nematoda is derived from the Greek word “Nemos,” which means “thread” and includes roundworms.