Table of Contents
What are the 4 cnidarians?
Cnidarians are classified into four main groups: the almost wholly sessile Anthozoa (sea anemones, corals, sea pens); swimming Scyphozoa (jellyfish); Cubozoa (box jellies); and Hydrozoa (a diverse group that includes all the freshwater cnidarians as well as many marine forms, and has both sessile members, such as Hydra …
What are three examples of cnidarians?
Mostly marine animals, the cnidarians include the corals, hydras, jellyfish, Portuguese men-of-war, sea anemones, sea pens, sea whips, and sea fans.
What phylum do spicules belong to?
The siliceous sponges form a major group of the phylum Porifera, consisting of classes Demospongiae and Hexactinellida. They are characterized by spicules made out of silicon dioxide, unlike calcareous sponges….Siliceous sponge.
| Siliceous sponges | |
|---|---|
| Hexactinellid spicule | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Porifera |
What makes a cnidaria?
Cnidarians share several basic characteristics. All Cnidaria are aquatic, mostly marine, organisms. They all have tentacles with stinging cells called nematocysts that they use to capture food. Cnidarians only have two body layers, the ectoderm and endoderm, separated by a jelly-like layer called the mesoglea.
Are spicules cells?
Spicules are microscopic crystalline structures which gives the sponges their rigidity and form. Spicule consists of spines or rays that radiate from a point. These are secreted by special mesenchymal amoebocytes called scleroblast cells.
What substances can spicules be made of?
Spicules are composed of either Calcium or Silica. Looking at composition is another way to narrow down possible sponge groupings.
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.
Why are collar cells and spicules important to cnidarians?
If collar cells and spicules are defining characteristics of the Phylum Porifera, then nematocysts define cnidarians. These tiny organelles, likened by Hickman to cocked guns, are both highly efficient devices for capturing prey and extremely effective deterrents to predators.
What kind of spicules do sponges have?
Most sponges belong to class Demospongiae (deh muh SPUN jee uh), the demosponges, and have spicules composed of spongin fibers, silica, or both. Natural bath sponges, like the ones in Figure 24.16,have spongin support. Class Calcarea (kal KER ee uh) consists of sponges with spicules composed of calcium carbonate.
How are sponges and cnidarians similar to each other?
Sponges are similar to what might have been the ancestor of animals: colonial, flagellated protists. The cnidarians, or the jellyfish and their kin, are the simplest animal group that displays true tissues, although they possess only two tissue layers.
What kind of body does a cnidarian have?
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. The mouth is usually on the concave side, and the tentacles originate on the rim of the umbrella.