Chapter 27.2 Flashcards
What are four examples of cnidarians?
Hydras, corals, jellyfish, and sea anemones
Where do most cnidarians live?
In the ocean
What is the gastrovascular cavity?
The hole for digestion
Where is the epidermis?
Outside
Where is the gastrodermis?
Inside
Where is the mesoglea?
The gel in between the epidermis and the gastrodermis
How are the cells of cnidarians arranged?
Into tissues
What kind of symmetry do cnidarians have?
Radial
What are the two basic forms of cnidarians?
Medusa and polyp. Cnidarians can be either or alternate between
Describe and give an example of medusa
Free-floating and umbrella shaped, jellyfish
Describe and give an example of polyp
Tubelike and often attached to a rock or other object, anemones
How are their nerve cells arranged and what do they do?
Into a nerve net where they coordinate sensory and motor activities
What can sensory cells detect? (3)
Light, chemicals and mechanical stimuli
What do the muscle-like cells if cnidarians do?
Aid in feeding and digestion
What are cnidocytes?
Stinging cells that are located in the finger like tentacles that surround the opening
What does the one opening of a cnidarian function as?
Mouth and anus
What is a nematocyst?
A threadlike organelle located in the cnidocyte that may contain toxins and is used for defense and to capture prey
How do cnidarians reproduce?
Sexually and asexually
Describe the life cycle of Obelia
Alternation between a polyp and a medusa stage. Once the gametes fuse, a planulae forms as a free-swimming larve
What is the common qualities of cnidarians?
The presence of stinging cells
Name the three types of cnidarians
Hydrazoans
Scyphozoans
Anthozoans
What are three examples of hydrazoans, and how advanced are they?
Obelia, hydras, Portuguese man of war
Most primitive
What is another name for scyphozoans, and how do they get food?
Jellyfish, active hunters
What are two examples of anthozoans and what do they exist as?
Sea anemones and corals. They exist only as polyps.
