Table of Contents
How are cnidarians different from mollusk?
Mollusks are invertebrates with soft unsegmented bodies that are often protected by a hard outer shell. Cnidarians are invertebrates that have stinging cells and take food into a central body cavity. Cnidarians use sting cells to capture food and defend themselves. Only bivalves can make pearls.
Are cnidarians tentacles retractable?
Members of the phyla Cnidaria and Bryozoa both have a circle of tentacles, which they use for feeding. Cnidarian tentacles are retractable, but Bryozoan tentacles are nonretractable. Cnidarian tentacles have stinging cells, but Bryozoan tentacles are covered with cilia.
Where are the tentacles on a cnidarian?
The Cnidarians include the hydroids, jellyfish, anemones, and corals. All Cnidarians have tentacles with stinging cells in their tips which are used to capture and subdue prey.
How are cnidarians and echinoderms different?
Echinoderms and cnidarians are quite different in many ways. Echinoderms include animals such as sea stars and sea urchins. Most live on the ocean floor, and they have radial symmetry. Cnidarians include animals such as jellyfish, and they all have stinging cells in their tentacles called nematocysts.
What allows cnidarians to be able to bend in different directions?
What allows cnidarians to be able to bend in different directions? Two different sets of muscles. How do nerve cells work with muscle cells to give the cnidarian movement? Electrical impulses trigger the each set of muscles for raising and bending.
How do Cnidaria and bryozoa differ?
Although they have some similarities, the Bryozoa and Cnidaria are two different phyla. They differ mainly in tentacle organization; for bryozoans they are arranged in a crown around the mouth and are ciliated (see detail above), whereas for cnidarians they are not ciliated.
What is the skeletal system of cnidarians?
Cnidarians have a hydrostatic skeleton. The contractile fibers act against the fluid-filled gastrovascular cavity. The movements are like a balloon; the animal can be short and thick or long and thin.
What is similar about echinoderms and cnidarians In what way does echinoderm symmetry differ from that of cnidarians?
What is similar about echinoderms and cnidarians? In what way does echinoderm symmetry differ from that of cnidarians? Cnidarians and echinoderms have radial symmetry; mollusks have bilateral symmetry. Cnidarians have no body cavity or cephalization; mollusks and echinoderms have a true coelom and cephalization.
What do the tentacles of a cnidarian mean?
All Cnidarians have tentacles with stinging cells in their tips which are used to capture and subdue prey. In fact, the phylum name “Cnidarian” literally means “stinging creature.”
What are the stinging cells of phylum Cnidaria?
All Cnidarians have tentacles with stinging cells in their tips which are used to capture and subdue prey. In fact, the phylum name “Cnidarian” literally means “stinging creature.”. The stinging cells are called cnidocytes and contain a structure called a nematocyst. The nematocyst is a coiled thread-like stinger.
What kind of symmetry does a cnidarian have?
Characteristics of Cnidarians. Cnidarians exhibit radial symmetry, which means their body parts are arranged symmetrically around a central axis. So, if you drew a line from any point at the edge of a cnidarian through the center and to the other side, you’d have two roughly equal halves. Cnidarians also have tentacles.
How did the cnidarian nematocyst get its name?
Cnidarians got their name from these stinging structures. The word cnidarian comes from the Greek word knide (nettle). The presence of nematocysts is a key feature of cnidarians. Cnidarians can use their tentacles for defense or for capturing prey.