Do flatworms have a ventral nerve cord?
Two main ventral thick nerve cords were consistently present in all examined species
. These always extended posteriorly, whereas most other nerve cords were radially distributed in the anterior part of the animal.
What animals have a ventral nerve cord?
Ventral nerve cord
Among the phyla exhibiting ventral nerve cords are
nematodes (roundworms), annelids (such as earthworms, and arthropods (such as insects and crayfish)
.
Do insects have a ventral nerve cord?
The Central Nervous System
Like most other arthropods,
insects have a relatively simple central nervous system with a dorsal brain linked to a ventral nerve cord
that consists of paired segmental ganglia running along the ventral midline of the thorax and abdomen.
Do flatworms have a nerve cord?
Do invertebrates have a ventral nerve cord?
One interesting difference between the nervous systems of invertebrates and vertebrates is that
the nerve cords of many invertebrates are located ventrally (along the belly)
whereas the vertebrate spinal cords are located dorsally (along the back).
What has a ventral main nerve cord?
Ventral nerve cords are found in
some phyla of the bilaterians, particularly within the nematodes, annelids and the arthropods
. Ventral nerve cords are well-studied within insects, have been described in over 300 species covering all the major orders, and have remarkable morphological diversity.
What is the location of the nerve cords in flatworm?
Flatworms (Planaria)
These cords are
connected to cerebral ganglia located in the head region
. The central nervous system has been described as “ladder-like” because of the nerves connecting the nerve cords. Flatworms have “auricles” that project from the side of the head.
Do arthropods have a ventral nerve cord?
The central nervous system of arthropods is segmented and can be roughly divided into the brain, located in the head at the anterior end, and
the ventral nerve cord spanning from the head to the caudal end, the abdomen
(Figure 1).
Do annelids have ventral nerve cord?
Annelids and all the more complex invertebrates share another characteristic feature,
a ventral nerve cord
with a pair of ganglia (or a single fused ganglion) in each segment, and longitudinal axon bundles between ganglia in adjacent segments (Fig.
Do invertebrates have a dorsal nerve cord?
Key Takeaways.
All invertebrate chordates share four main characteristics: a notochord, a dorsal nerve tube
, a post-anal tail, and pharyngeal gill slits. All of these characteristics are observed at some point in chordate development.
What nervous system does a flatworm have?
Flatworms have a
cephalized nervous system
that consists of head ganglion, usually attached to longitudinal nerve cords that are interconnected across the body by transverse branches. Excretion and osmoregulation by flatworms is controlled by “flame cells” located in protonephridia (these are absent in some forms).
Do worms have nerves?
The earthworm’s ‘brain’.
Earthworms have a simple nervous system
. The cerebral ganglion is connected to a ventral nerve cord that runs the length of the body. Each segment is connected to this cord, allowing earthworms to move and respond to light, touch, chemicals, vibrations and more.
Do worms have a central nervous system?
It has a central and peripheral nervous system
. Its central nervous system consists of two ganglia above the mouth, one on either side, connected to a nerve running along its length to motor neurons and sensory cells in each segment. Large numbers of chemoreceptors concentrate near its mouth.
Do nematodes have a ventral nerve cord?
In addition,
all nematodes have a major nerve cord running longitudinally along the ventral midline of the body, from head to tail
(Figure 2). This ventral nerve cord contains cell bodies as well as processes, many of which project into the nerve ring where they make and receive synapses with other neurons.
Where is the ventral nerve cord located worm?
ii) Nerve cord of earthworm:
Nerve cord arises from the sub-pharyngeal ganglia. It extends behind up to the posterior end of body in
mid ventral axis beneath the ventral vessel
. Both cords appear as a single nerve cord as they are fused and enclosed in a common sheath.
Do flatworms have ganglia?
In the flatworm Planaria,
the brain consists of two cerebral ganglia
(clusters of nerve cells) from which nerve cords extend the length of the body.
What has a dorsal nerve cord?
The dorsal nerve cord is a unique feature to chordates, and it is
mainly found in the Vertebrata chordate subphylum
. The dorsal nerve cord is only one embryonic feature unique to all chordates, among the other four chordate features– a notochord, a post-anal tail, an endostyle, and pharyngeal slits.
What is the position of ventral nerve cord in planaria?
The planarian CNS is located
on the ventral side of the body
, and composed of a mass of cephalic ganglions in the head region and a pair of ventral nerve cords (VNC).
Do echinoderms have a dorsal nerve cord?
How is the nervous system of a flatworm more complex than the sensory cells and nerve net of cnidarian?
These organisms have a more complex nervous system in detecting external stimuli compared to cnidarians and sponges,
because these species have a series of nerve cells referred to as ganglia that act as their brain
.
Do Platyhelminthes have a central nervous system?
Flatworms’ bodies are bilaterally symmetrical and they have a defined head and tail region.
They have a central nervous system containing a brain and a nerve cord
. Clusters of light-sensitive cells on either side of their head make up what are called eyespots.
What animals have no central nervous system?
The only multicellular animals that have no nervous system at all are
sponges and microscopic bloblike organisms called placozoans and mesozoans
. The nervous systems of ctenophores (comb jellies) and cnidarians (e.g., anemones, hydras, corals and jellyfishes) consist of a diffuse nerve net.
Do arthropods have dorsal nerve cord?
The arthropod nervous system consists of a dorsal brain and a ventral, ganglionated longitudinal nerve cord
(primitively paired) from which lateral nerves extend in each segment.
Does cockroach have ventral nerve cord?
In cockroach, nerve cord is present on the ventral side
. It consists of two solid longitudinal nerves. The nerve cord extends in between sub- esophageal ganglia and the last abdominal ganglia present in the 7th segment.
What do annelid worms and arthropods have in common?
Both Annelida and Arthropoda
consist of cerebral ganglion with ventral nerve cord
. Both animals consist of a mouth at one end of the body and the anus in the other end. Both animals undergo sexual reproduction, and fertilization can be either internal or external. Both animals have similar types of larvae.
Do chordates have ventral nerve cords?
In chordates, for example,
besides a dorsal hollow nerve cord and ventral heart
, there evolved a dorsal notochord, ventrolateral gill slits, a ventral endostyle in the pharynx, and a dorsal postanal tail. None of these is found in protostomes, which would have added other organs.
Which one of the following is not a characteristic of phylum Annelida * A ventral nerve cord B closed circulatory system C segmentation D Pseudocoelom?
Thus being ‘
pseudocoelomate
‘ is the only character not possessed by animals of the phylum Annelida. Hence, the correct answer is option A, i.e., Pseudocoelomate. Additional information: animals belonging to this phylum breathe through the skin as they lack lungs.
Which one of the following is not a characteristic of phylum Annelida ventral nerve cord closed circulatory system segmentation Pseudocoelom?
Pseudocoelom is not a characteristic of phylum Annelida
. Annelids are the protostomes taking a series of rings or segments that mark up their whole body. Annelids have a great, well-developed coelom and also have a closed circulatory system so pseudocoelom is not a characteristic of Annelida.
Do frogs have a dorsal nerve cord?
Do chordates have a dorsal hollow nerve cord?
What is the difference between invertebrates and non vertebrate chordates?
Chordates include both vertebrates and invertebrates that have a notochord.
Invertebrate chordates do not have a backbone
. Invertebrate chordates include tunicates and lancelets. Both are primarily marine organisms.
What characteristics do flatworms have?
Where is the nervous system of most form of Platyhelminthes located?
In each of the classes of Platyhelminthes, we see the nervous system concentrated in
the anterior region of the animal
, most commonly the head of the animal.
What are the defining features of flatworms?
Features of Flatworms
Flatworms have no true body cavity, but they do have bilateral symmetry
. Due to the lack of a body cavity, flatworms are known as acoelomates. Flatworms have an incomplete digestive system. This means that the digestive tract has only one opening.
Do worms have nerve endings?
The same applies with simple organisms like the earthworm. Yes, they only have ganglia for a brain, and yes,
they have a very basic ventral nerve cord running down the length of its body
.
What is double ventral nerve cord?
The ventral nerve cord is a bundle of nerve fibers, typically a solid double-strand (pair) of nerve cords, that runs along the longitudinal axis of some phyla of elongate invertebrates, and forms part of the invertebrate central nervous system.
