Phylum Cnidaria Body Symmetry Quiz

Explanation
CNIDARIANS exhibit all of the above characteristics. They have radial symmetry, meaning their body parts are arranged around a central axis. They also possess stinging cells called cnidocytes, which they use for defense and capturing prey. Additionally, most cnidarians have tentacles that surround their mouth and are used for feeding and sensing the environment. Therefore, all of these characteristics are exhibited by cnidarians.

Explanation
Cnidarians have a hydrostatic skeleton, which is a fluid-filled cavity that provides support and shape to their bodies. Limestone is a type of rock and not a type of skeleton. It is not found in cnidarians or any other living organisms as a structural component. Therefore, the answer is limestone.

Explanation
Nematocytes are specialized cells found in the tentacles of cnidarians, such as jellyfish and sea anemones. These cells are responsible for stinging their prey by injecting poison into them. They can also secrete a sticky substance that causes the prey to stick to the tentacles. However, nematocytes are not located in the mesoglea of cnidarians. The mesoglea is a jelly-like substance that fills the space between the outer epidermis and the inner gastrodermis of cnidarians. Therefore, the statement "located in the mesoglea of cnidarians" is not true of nematocytes.

Explanation
In cnidarians, fertilization generally takes place in the water column. This means that the male and female gametes are released into the surrounding water, where they come into contact and fertilization occurs. This method allows for the dispersal of gametes over a larger area, increasing the chances of successful fertilization. Additionally, cnidarians often have separate sexes, so this method allows for the mixing of gametes from different individuals. Fertilization in the water column also reduces the risk of self-fertilization, as the gametes have a higher chance of encountering gametes from different individuals.

Explanation
Corals and jellyfish are classified together mainly because they both have stinging tentacles. Stinging tentacles are a characteristic feature of cnidarians, which include corals and jellyfish. These tentacles contain specialized cells called cnidocytes that can inject venom into their prey or predators. This common trait is one of the main reasons why corals and jellyfish are classified together.