What are the distinguishing features of nematodes?
Following are the important characteristics of Nematoda:
- Their body is bilaterally symmetrical and triploblastic.
- They are cylindrical in shape.
- They exhibit tissue level organization.
- Their body has a cavity or pseudocoelom.
- The alimentary canal is distinct, with the mouth and the anus.
- They are sexually dimorphic.
How would you distinguish a nematode from another microscopic worm like organism?
Unlike other worms that have two bands of muscles, nematodes only have longitudinal muscles. This explains their characteristic thrashing movement, as they can move only by contracting the long muscles on either side of their body and wriggling forward.
Why do nematodes move side to side?
Nematodes move by contraction of the longitudinal muscles. Because their internal pressure is high, this causes the body to flex rather than flatten, and the animal moves by thrashing back and forth.
What type of body shape do nematodes have?
The nematode body is cylindrical, elongated and smooth with no limbs protruding, such as is seen in the common garden worm though generally on a smaller scale. The body is contained within a tough elastic cuticle which in many species forms elaborate structures useful for identification.
What are the two types of nematodes?
Nematodes that commonly parasitise humans include ascarids (Ascaris), filarias, hookworms, pinworms (Enterobius), and whipworms (Trichuris trichiura). The species Trichinella spiralis, commonly known as the ‘trichina worm’, occurs in rats, pigs, bears, and humans, and is responsible for the disease trichinosis.
What do all nematodes have in common?
Commonly referred to as roundworms, these creatures can range in size from about 3/4 of an inch to nearly 30 feet in length. Despite the diversity found in this phylum’s inhabitants, they all share some characteristics, including a primitive body cavity, a simple digestive system, and a flexible external covering.
Can you see nematodes?
Being slender and transparent, they cannot often be seen by the naked eye. Other groups of worms may be confused with nematodes. With a few exceptions, if you can see an organism, with the naked eye, it is not a plant-parasitic nematode.
Are nematodes bad for humans?
Humans can also be invaded by nematodes. The good news is that these are much smaller than Placentonema! The bad news is that these invaders can cause serious diseases. The nematode Wuchereria bancrofti for example affects over 100 million people throughout tropical parts of the world.
Can nematodes kill humans?
There are many species of parasitic nematodes, and different species infect different hosts: some infect humans, some infect other animals and some infect plants. Chronic infection with intestinal nematodes can cause anemia, loss of appetite, gastrointestinal distress and, in some cases, even death.
Do nematodes have a brain?
In their overall structure, all nematode nervous systems exhibit a number of common, invariant features. The central nervous system consists primarily of a so-called circumoral brain or nerve ring, consisting of annular neuropil that encircles the neck of the pharyngeal muscle (Figure 1).
Why are nematodes so successful?
The reasons for the success of the Nematoda as parasites probably include the presence of an environmentally protective cuticle, facultative diapause (like the dauer stage of Caenorhabditis elegans), biochemical adaptations to existence in extreme conditions, and the use of a variety of reproductive strategies.
Do nematodes have a respiratory system?
While nematodes have digestive, reproductive, nervous and excretory systems, they do not have discrete circulatory or respiratory systems. Nematodes use chemosensory and mechanosensory neurons embedded in the cuticle to orient and respond to a wide range of environmental stimuli.
Why do nematodes have Pseudocoelom?
The body cavity of nematodes is called a pseudocoelom because it is not fully lined by mesodermal cells as in the true coelomic cavity of all vertebrates.
Is a nematode a Pseudocoelomate?
The pseudocoelomates include the nematodes, rotifers, gastrotrichs, and introverts. Some members of some other phyla are also, strictly speaking, pseudocoelomate. These four phyla of tiny body size (many species no larger than the bigger protozoans) are placed together in part because they…
What is the major unifying Aschelminth feature?
The major unifying aschelminth feature is a pseudocoelom. The pseudocoelom is a typeof body cavity that develops from the blastocoel (the primitive cavity in the embryo)and is not fully lined by mesoderm, as in the true coelomates. The body cavity of pseudocoelom is coversed by flexible nonliving collagen cuticle.