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The medusa is a free-swimming form; it moves by rhythmic muscular contractions of the bell, providing a slow propulsive action against the water. The other principal body type of the adult cnidarian is the polyp, a stalked, sessile (attached) form.
- Are cnidarians sessile or free swimming?
- Are polyps free swimming?
- Are polyps free swimming cnidarians?
- What is the free swimming body form of cnidarians?
- Are cnidarians sessile?
- What is polyp in cnidarians?
- What is polyp Medusa?
- Are all polyps sessile?
- How will you differentiate a Medusa from polyps?
- How does a polyp turn into a medusa?
- Can polyps swim?
- Which cnidarians are usually in the medusa stage?
- Why do so many cnidarians have both medusa and polyp stages during their life cycle?
- Which organism possesses both a polyp and medusa phase of life?
- What body systems do cnidarians have?
Are cnidarians sessile or free swimming?
Most adult cnidarians appear as either free-swimming medusae or sessile polyps, and many hydrozoans species are known to alternate between the two forms.
Are polyps free swimming?
polyp and medusa, names for the two body forms, one nonmotile and one typically free swimming, found in the aquatic invertebrate phylum Cnidaria (the coelenterates).
Are polyps free swimming cnidarians?
Cnidarians have two basic body forms, medusa and polyp. Medusae, such as adult jellyfish, are free-swimming or floating. They usually have umbrella-shaped bodies and tetramerous (four-part) symmetry. ... Polyps, in contrast, are usually sessile.
What is the free swimming body form of cnidarians?
Many cnidarian species have two different body forms during their lives. One is the free-swimming form, called the medusa (a jellyfish for instance). The other is an attached form called the polyp (which resembles a tiny sea anemone).
Are cnidarians sessile?
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.
What is polyp in cnidarians?
polyp, in zoology, one of two principal body forms occurring in members of the animal phylum Cnidaria. The polyp may be solitary, as in the sea anemone, or colonial, as in coral, and is sessile (attached to a surface). ... The lower end of the polyp typically is adapted for attachment to a surface.
What is polyp Medusa?
Polyp is a sessile life cycle stage of species who belong to phylum cnidaria. Famous examples of polyp are sea anemones and adult corals. ... Medusa is a life cycle stage of the species who belongs to cnidaria phylum. One of the most common examples of species having a medusa life cycle is Hydrozoa or jellyfish.
Are all polyps sessile?
Not all polyps are the same; there are several different types (inflammatory, hyperplastic, adenomatous, and villous) and two shapes, sessile and pedunculated. A sessile polyp is one that is flat and does not have a stalk.
How will you differentiate a Medusa from polyps?
Polyp are sessile while medusa are mobile. Polyp present a tubular shape with the mouth facing the water upwards,while medusa present a bell shape with the mouth facing the water downwards. Polyp do not have a manubrium, while medusa of the class Hydrozoa present a tube hanging down from the bell known as manubrium.
How does a polyp turn into a medusa?
In organisms that exhibit both forms, such as members of the cosmopolitan genus Obelia, the polyp is the asexual stage and the medusa the sexual stage. In such organisms the polyp, by budding, gives rise to medusae, which either detach themselves and swim away or remain permanently attached to the polyp.
Can polyps swim?
Medusae swim by jet propulsion (see below Tissues and muscles). However, most do so weakly and are carried passively by currents over long distances. Polyps are generally sedentary.
Which cnidarians are usually in the medusa stage?
Scyphozoans are the more commonly thought of Cnidarians. They have a true medusa stage and can be very large. This are often referred to as Jellyfish, the largest one known can have a bell over 10ft in diameter. Scyphozoans spend most of their life in the medusa stage and some species may often lack a polyp stage.
Why do so many cnidarians have both medusa and polyp stages during their life cycle?
Some cnidarians are dimorphic, that is, they exhibit both body plans during their life cycle. In these species, the polyp serves as the asexual phase, while the medusa serves as the sexual stage and produces gametes.
Which organism possesses both a polyp and medusa phase of life?
They are the most primitive of animals whose cells are organized into distinct tissues, but they lack organs. Cnidarians have two body forms—polyp and medusa—which often occur within the life cycle of a single cnidarian. Sea nettle (Chrysaora fuscescens).
What body systems do cnidarians have?
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.
