Question

the hawaiian bobtail squid has a symbiotic relationship with the bacteria that they host. this nocturnal squid lives primarily in shallow water, so it needs bioluminescence to camouflage itself against the starlit night sky. seen from below, a solid black shadow is much more obvious than a shape that mimics a starry sky. the bobtail squid relies on specific, bioluminescent bacteria that inhabit the squid’s light organ and begin to glow when it gets dark. when morning comes, the squid expels 95% of the bacteria from its light organ; the squid keeps and nourishes the other 5% so their number will increase throughout the day. by the time darkness descends again, there are enough bacteria present in the squid’s light organ to camouflage it once more. bioluminescence manifests in a variety of colors, but the majority of the bioluminescence produced in the ocean appears blue - green in color. light waves move differently in water, and blue - green light waves are shorter than other colors; they can travel and be seen more easily in deep water. it is almost impossible to perceive the color red in the ocean, thus many fish are red in color because it makes them nearly invisible to other fish. one exception is the dragonfish, which emits red... assessment questions why is the bobtail squid’s relationship with bacteria described as symbiotic in paragraph 5? a. the bacteria and the bobtail squid share a main predator. b. the bobtail squid consumes the bacteria for nourishment. c. the bacteria survives to the detriment of the bobtail squid. d. the bobtail squid nourishes bacteria that provide it with light.

Explanation:

To determine why the relationship is symbiotic, we analyze each option:

• Option A: The passage does not mention a shared predator, so this is incorrect.
• Option B: The squid does not consume the bacteria for nourishment; it nourishes the 5% it keeps, so this is wrong.
• Option C: A symbiotic relationship where one is harmed (detriment) is not the case here. The squid and bacteria help each other, so this is incorrect.
• Option D: The squid nourishes the bacteria (keeps and nourishes 5% so their number increases) and the bacteria provide light for the squid to camouflage, showing mutual benefit, which is symbiotic.

Answer:

D. The bobtail squid nourishes bacteria that provide it with light.