what is the free floating body form of cnidarians


What Is The Free Floating Body Form Of Cnidarians?

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.Jun 12, 2006

Which body form of cnidarians are adapted to floating and free-swimming?

Cnidarians’ bodies typically take one of two forms: the polyp or the medusa. The polyp form is adapted for a sedentary or sessile lifestyle (attached to a surface), while the medusa form is adapted for floating or free-swimming. Sea anemones and corals are all polyps.

What are the two body forms of cnidaria?

Cnidarians have two body forms—polyp and medusa—which often occur within the life cycle of a single cnidarian. Sea nettle (Chrysaora fuscescens). The body of a medusa, commonly called a jellyfish, usually has the shape of a bell or an umbrella, with tentacles hanging downward at the margin.

What is the body structure of cnidarians?

The body of a cnidarian consists of two cell layers, ectoderm and endoderm. The cellssurround a digestive cavity called the coelenteron (see Figure below). Cnidarians have a simple digestive system. The single opening is surrounded by tentacles, which are used to capture prey.

What body form do cnidarians move?

The Medusas Stage allows for the cnidarians to actively move using their long tentacles to pull the water into themselves to gain nutrients.

Which of the body form in cnidarians is umbrella shaped and free living?

medusa, in zoology, one of two principal body types occurring in members of the invertebrate animal phylum Cnidaria. It is the typical form of the jellyfish. The medusoid body is bell- or umbrella-shaped.

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Are free-swimming members of the phylum Cnidaria?

Most adult cnidarians appear as either free-swimming medusae or sessile polyps, and many hydrozoans species are known to alternate between the two forms.

What are the two types of body forms in the phylum Cnidaria and which types of cnidarians are each dominant?

Cnidarians have two distinct morphological body plans known as polyp, which are sessile as adults, and medusa, which are mobile; some species exhibit both body plans in their lifecycle.

What are the two body forms of cnidarians and how do they differ?

Cnidarians have two distinct body plans, the medusa (a) and the polyp (b). … In these species, the polyp serves as the asexual phase, while the medusa serves as the sexual stage and produces gametes. However, both body forms are diploid. An example of cnidarian dimorphism can be seen in the colonial hydroid Obelia.

What are the two body forms of cnidarians How are these similar How are they different?

There are two major body forms among the Cnidaria – the polyp and the medusa. Sea anemones and corals have the polyp form, while jellyfish are typical medusae. When you look at them, you can see that these body forms are the same except that one is upside down. … Cnidaria have no organs like hearts or lungs.

Are cnidarians carnivores?

All cnidarians are carnivores. Most use their cnidae and associated toxin to capture food, although none is known actually to pursue prey. Sessile polyps depend for food on organisms that come into contact with their tentacles.

How do cnidarian colonies form?

Cnidarian Colonies

Some types of cnidarians are also known to form colonies. … One polyp is filled with air to help the colony float, while several feeding polyps hang below with tentacles. The tentacles are full of nematocysts.

What is the common adaptation of cnidarians?

What is the common adaptation , which unites them into the common group of Cnidaria? Their ability to sting their prey. What language was the word Cnidaria derived from and what does the word mean? The language the word Cnidaria derived from is Greek and it means stinging nettle.

How do cnidarians move?

They contract their hollow, saucer-shaped bodies (called bells) to force water out, which propels them forward. Their long. tentacle-like arms, which trail out behind them, are used to sting and capture prey.

Which body form of the cnidarians is sessile quizlet?

Like sea anemones, coral polyps have stinging cells and the are both sessile.

How do cnidarians excrete?

Cnidarians take in food through their mouths, which is then digested in the coelenteron. Nutrients are then passed to other areas of the body for use, and waste products are expelled either through the mouth or through surface cells via water circulation.

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Which of the following is a trait of cnidarians?

All Cnidarians share particular trait: tentacles with stinging nematocysts. The nematocysts act like tiny harpoons, reacting to stimuli by hurling out small stinging cells that both poison and hook potential prey.

What type of symmetry do cnidarians have?

radial symmetry
The bilateral symmetry of Cnidaria is thought to be inherited from the common ancestors of both cnidarians and triploblastic bilaterians. The secondary radial symmetry of Cnidaria evidently is a result of the adaptation to the sessile mode of life.

What type of circulatory system do cnidarians have?

Cnidarians lack organs. This means that they do not have respiratory or circulatory systems. Like the cells in sponges, the cells in cnidarians get oxygen directly from the water surrounding them.

What characteristics of phylum Cnidaria are most important in distinguishing it from other phyla?

What characteristics of Phylum Cnidaria are the most important in distinguishing it from other phyla? They are sessile, radial symmetry, production of nematocysts.

What did cnidarians evolved from?

The exact relationships between the different cnidarian groups are unknown. An alternative view is that anthozoans are the stem of the phylum, which evolved from bilateral flatworms and is secondarily simplified. … A corollary to this theory is that the polyp is the ancestral body form.

What are the characteristics of phylum Cnidaria?

What are the Characteristics of Cnidarians?
  • They are characterized by the presence of stinging cells called Cnidoblast and a cavity called coelenterates, justifying the name Cnidaria or Coelenterata.
  • They are exclusively aquatic and marine.
  • They are radially symmetrical and diploblastic animals.

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 the larva of a cnidarian called?

planula, plural planulae, free-swimming or crawling larval type common in many species of the phylum Cnidaria (e.g., jellyfish, corals, and sea anemones). The planula body is more or less cylindrical or egg-shaped and bears numerous cilia (tiny hairlike projections), which are used for locomotion.

What is cnidarians nervous system?

The basic plan of the cnidarian nervous system is that of a nerve net which, at some locations, has condensed to form nerve plexuses, or circular or longitudinal nerve tracts which may be syncytia. … All these data indicate that evolutionarily “old” nervous systems use peptides as transmitters.

How are cnidarians involved in the formation of coral reefs?

Coral cnidarians produce polyps that form colonies and each secretes calcium carbonate that collectively produces a coral reef.

How does digestion in cnidarians differ from digestion in 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.

What is the role played by the cnidarians in the ecosystem?

Cnidarians are very much important as predators in the open ocean. They help in the smooth functioning and working of the food chain and food web of the ocean ecosystem a lot. Cnidarians like the Coral reefs are considered to be one of the most diverse and valuable ecosystems on earth.

What is a polyp form?

A colon polyp is a small clump of cells that forms on the lining of the colon. Most colon polyps are harmless. But over time, some colon polyps can develop into colon cancer, which may be fatal when found in its later stages. Anyone can develop colon polyps.

Where are cnidarians found?

Cnidarians can be found in almost all ocean habitats. They may live in water that is shallow or deep, warm or cold. A few species live in freshwater. Some cnidarians live alone, while others live in colonies.

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How do cnidarians feed?

Cnidarians are carnivores, and some can also consume plant matter. They catch their food using their nematocysts or through filter feeding. Cnidarians digest their food using a primitive digestive system that contains no organs–they have a mouth (which also serves as the anus) and a gastrovascular cavity.

Are cnidarians Autotrophs or Heterotrophs?

name some cnidarians. What is the defining trait for cnidarians? Describe the body plans of cnidarians. Explain cnidocyctes and how they help cnidarians eat.

How do phylum Cnidaria reproduce?

Reproduction of Cnidarians

In general, polyps primarily reproduce asexually by budding, however, some produce gametes (eggs and sperm) and reproduce sexually. Medusae usually reproduce sexually using eggs and sperm. … The planula then develops into a polyp that can reproduce either sexually or asexually.

How do cnidarians maintain homeostasis?

Cnidarians secrete hormones from glands that allow them to maintain homeostasis. They use direct diffusion in order to circulate the necessary nutrients through its body.

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