Cnidarian, also called coelenterate, any member of the phylum Cnidaria (Coelenterata), a group made up of more than 9,000 living species. Mostly marine animals, the cnidarians include the corals, hydras, jellyfish, Portuguese men-of-war, sea anemones, sea pens, sea whips, and sea fans.
How are cnidarians classified?
Cnidarians are classified into four main groups: non-moving (sessile) Anthozoa (sea anemones, corals, sea pens); Cubozoa (box jellies);swimming Scyphozoa (jellyfish); and Hydrozoa, a broad group that includes all the freshwater cnidarians as well as many marine forms. Cnidaria have no organs like hearts or lungs.
What level of Organisation is found in cnidarians and how is it different from that of sponges?
These organisms show a simple organization. Sponges have multiple cell types that are geared toward executing various metabolic functions. Cnidarians have outer and inner tissue layers sandwiching a noncellular mesoglea. Cnidarians possess a well-formed digestive system and carry out extracellular digestion.
How is the body plan organized in cnidarians?
Cnidarians have a slightly more organized body plan, and have tissues, but no organs. Most cnidarians have two tissue layers. The outer layer, the ectoderm, has cells that aid in capturing food and cells that secrete mucus. The body plans cnidarians generally have radial symmetry (Fig.
Are Coelenterates and cnidarians the same?
Cnidaria and Ctenophora are two types of phyla composed of coelenterates. Cnidarians live in both freshwater and marine habitats while ctenophores only live in the sea. Cnidarians are diversified animals than ctenophores. Coelenterates are invertebrates.
What are the two forms of cnidarians?
They have a simple body consisting of a central gut cavity surrounded by tentacles. A jelly-like substance called mesoglea lies between the outer and inner layers of the body. There are two basic cnidarian body shapes: a polyp form, which is attached to a surface; and an upside-down free-floating form called a medusa.
What are 2 body forms of cnidarians?
What 3 structures do all cnidarians possess?
In addition to a primitive digestive cavity, cnidarians have a decentralized nervous system, muscle tissue, reproductive tissues, and a hydrostatic skeleton. A hydrostatic skeleton is maintained by the internal pressure of fluids within the organism.
What are the 2 body forms of cnidarians?
What level of organization are platyhelminthes?
organ-level
Characteristics. Flatworms are flattened and have bilateral symmetry. They are triploblastic (have 3 embryonic tissue layers: ectoderm, mesoderm, and endoderm) and therefore have organ-level of organization.
What kind of organization does a cnidarian have?
There is no level of organization past cells in sponges. Cnidarians, on the other hand, have tissues, a higher level of organization. Tissues allow for some forms, like box jelly fish, to have eyes (this is just one of many advantages of tissues). Cnidarians’ level of organization stops there though, they have no organs (heart, brain, etc.).
Which is more complex a Porifera or a cnidarian?
Cnidarians represent a more complex level of organization than Porifera. They possess outer and inner tissue layers that sandwich a noncellular mesoglea. Cnidarians possess a well-formed digestive system and carry out extracellular digestion.
How many germ layers does a cnidarian have?
4. Germ Layers: Cnidarians are diploblastic animals, i.e., derived only from two embryonic germ layers, viz., ectoderm and endoderm. 5. Level of Organization:
What kind of symmetry does the Cnidaria have?
The Phylum Cnidaria includes such diverse forms as jellyfish, hydra, sea anemones, and corals. Cnidarians are radially or biradially symmetric, a general type of symmetry believed primitive for eumetazoans.
