Which of the following multicellular organisms were among the first to evolve light-sensing photoreceptive organs?
A)fish
B)amphibians
C)cyanobacteria
D)cnidarians and flatworms

Question

Quizplus · Accepted Answer

Cnidarians (jellyfish, corals, etc.) and flatworms were among the first multicellular organisms to evolve light-sensing photoreceptive organs called eyespots. These rudimentary structures allowed them to detect the direction of light and shadows, which was useful for behaviors like finding food, avoiding predators, and swimming towards light for photosynthesis (in the case of cnidarians). While fish and amphibians have more advanced eyes with lenses and retinae, they evolved later than cnidarians and flatworms. Cyanobacteria, which are single-celled organisms, do not have photoreceptive organs.

Which of the Following Multicellular Organisms Were Among the First