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By the end of this section, you will be able to:
  • Describe the structural organization of nematodes
  • Understand the importance of Caenorhabditis elegans in research
  • Compare the internal systems and appendage specializations of phylum Arthropoda
  • Discuss the environmental importance of arthropods
  • Discuss the reasons for arthropod success and abundance

Superphylum ecdysozoa

The superphylum Ecdysozoa contains an incredibly large number of species. This is because it contains two of the most diverse animal groups: phylum Nematoda (the roundworms) and Phylum Arthropoda (the arthropods). The most prominant distinguising feature of Ecdysozoans is their tough external covering called the cuticle. The cuticle provides a tough, but flexible exoskeleton tht protects these animals from water loss, predators and other aspects of the external environment. All members of this superphylum periodically molt, or shed their cuticle as they grow. After molting, they secrete a new cuticle that will last until their next growth phase. The process of molting and replacing the cuticle is called ecdysis, which is how the superphylum derived its name.

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. Stoll, N. R., “This wormy world. 1947,” Journal of Parasitology 85(3) (1999): 392-396. 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. Nematodes are present in all habitats with a large number of individuals of each species present in each. The free-living nematode, Caenorhabditis elegans has been extensively used as a model system in laboratories all over the world.

Morphology

In contrast with cnidarians, nematodes show a tubular morphology and circular cross-section. These animals are pseudocoelomates and show the presence of a complete digestive system with a distinct mouth and anus. This is in contrast with the cnidarians, where only one opening is present (an incomplete digestive system).

Questions & Answers

what is oxidation?
Rose Reply
 the state or result of being oxidized
Emmanuel
hahahaha thanks, but my teachers requires a thorough meaning about that
Rose
Is the process of oxidizing ,the addition of oxygen to a compound with a loss of electrons, always accompanied by reduction
Korletey
loss of electron....
Anwar
thank you. 😊
Rose
thank you. 😊
Rose
thank you. 😊
Rose
what is oxidized
Oyebanji
the process or result of oxidizing or being oxidized.
Jersey
what is genetic
Chibawa Reply
name the enzymes that i found in the saliva
Valuables Reply
draw a bacterium cell and label
Kadijah Reply
What are the osmoregulatory functions of the kidney?
bisi Reply
filter
Meenu
What is ecology
Hebert Reply
what is cell
Etama Reply
cell is the basic unit of life
Asiatou
cell is the basic structural and functional unit of an living organism
Darshan
a cell is the smallest and most basic unit of a living thing
John
cell is the basic unit of life. we are made up of 60,000 billions of cells.Each cell carry out a specific function in the body.
Pallavi
A cell is the smallest basic functioning unit of life.
Ali
where is the pectoral gridle located?
Tiania Reply
What is hypotonic
Bright Reply
what is hypotonic
Dangaya
Hypotonic means weak solution
Ali
the difference between the two cells
Obeng Reply
explain the courses and the correction of lon term sightedness and short term sightedness
Isaac Reply
long sightedness is said to be like someone that can see far object clearly why short sightedness is someone that only can see near obect
SHEDRACK
why drinking excess alcohol causes thirst and dehydration
uwikuzo Reply
Can we chat about nutrition please?
Elia
yes
Uzair
sure
Uzair
Uhm why is it so important to follow the nutritional process?
Elia
BC it contribute to the source of life
SHEDRACK
what is reproduction
smart Reply
it is d act of bringing young ones to life
Oyebanji
to ensure survival of a species🚴‍♀️
Michelle
what is a genotype
Collins
what is hazardous
smart
a cell is the smallest unit of a living thing. so we all have cell
smart
It is the formation of a zygote resulting from the fusion of the sperm cell with the ovum.Thus,this results in the production of new species which are genetically dissimilar from their parent cells.
Pallavi
yes we all have cell round our body without the existances of cell them they will be no life in us as human
SHEDRACK
what is size of cell
Mohd Reply
what is size of Hart
Mohd
nanometers=um sign thingie
Michelle
microns=nanometers
Michelle
monomers and polymers of nucleic acids?
Jyrl Reply
dna and rna involvement
Michelle

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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