Do flatworms have a nervous system?
The nervous system of a free-living flatworm such as Planaria consists of a brain, longitudinal nerve cords, and peripheral nerve plexuses (interlacing networks of peripheral nerves; from Latin plectere, “to braid”).
What nervous system structure is used by flatworm?
The bilaterally flattened body of flatworms preserves a common organization of the central nervous system (CNS). The CNS of flatworms consists of: (i) the orthogon, composed of main longitudinal nerve cords and transverse commissures that form a ladder-like network.
What animals have no 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 planarians have a nervous system?
Planarians are considered to be among the most primitive animals which developed the central nervous system (CNS).
Do flatworms have sense organs?
Flatworms are generally hermaphroditic—functional reproductive organs of both sexes occurring in one individual. Like other advanced multicellular animals, they possess three embryonic layers—endoderm, mesoderm, and ectoderm—and have a head region that contains concentrated sense organs and nervous tissue (brain).
Do flatworms have brain?
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.
How many eyes do flatworms have?
While many species have two eyes (e.g. Dugesia or Microplana), others have many more distributed along the body (e.g. most Geoplaninae). Sometimes, those species with two eyes may present smaller accessory or supernumerary eyes.
What type of body cavity do flatworms have?
gastrovascular cavity
How quickly do flatworms reproduce?
Through a process called “fission,” planarians can reproduce asexually by simply tearing themselves into two pieces — a head and a tail — which then go on to form two new worms within about a week.
Can flatworms regenerate?
Planarians are flatworms that possess an amazing ability to regenerate themselves. If you cut one planarian down the middle, each half would reform its missing parts, and you would have two planarians in a matter of weeks. Embryogenesis lasts for approximately two weeks for this flatworm species.
How do flatworms regenerate lost tissue?
In humans, only embryonic stem cells and germ cells are pluripotent — with the ability to create all cell types in the body. In the planarian flatworm Schmidtea mediterranea, certain dividing cells, called neoblasts, have long been identified as essential for the regeneration that repairs the worm’s tissues.
In what way can flatworms regenerate themselves?
Flatworms, the masters of regeneration – but nothing can happen without stem cells. Planarians are known as masters of regeneration: they can re-build any part of their bodies after amputation. This ability relies on a large number of pluripotent stem cells.