Question

Which of the following describes a difference between cnidarians and ctenophores?

a. Cnidarians have choanocytes, whereas ctenophores have cnidocytes

b.Ctenophores swim through the water mouth-first, whereas cnidarians medusae's power stroke propels them aboral-side first

c. Ctenophores have an acellular layer between an external and internal layer of cells, whereas cnidarians' external and internal layer of cells touch each other directly

d. Cnidarian tentacles can retract, whereas ctenophore tentacles cannot

true or false: The symbiosis between corals and zooxanthellae is unusual, because the coral can survive forever if the zooxanthellae leave the coral.

Answer 1

b.Ctenophores swim through the water mouth-first, whereas cnidarians medusae's power stroke propels them aboral-side first.

The symbiosis between corals and zooxanthellae is unusual, because the coral can survive forever if the zooxanthellae leave the coral. IT IS TRUE

Most reef-building corals have a unique partnership with tiny algae called zooxanthellae. The algae live within the coral polyps, using sunlight to make sugar for energy. This energy is transferred to the polyp, providing much needed nourishment. In turn, coral polyps provide the algae with carbon dioxide and a protective home.

Corals also eat by catching tiny floating animals called zooplankton. At night, coral polyps come out of their skeletons to feed, stretching their long, stinging tentacles to capture critters that are floating by. Prey are pulled into the polyps’ mouths and digested in their stomachs.

Corals leave zooxanthellae when water is warm. Then coral becomes white (Coral Bleaching).

But Corals also eat prey. so they cav survive.