Question

A lichen is an organism that structurally appears to be a single organism. But a lichen is actually two different organisms—a fungus and green algae—living together as one organism. The fungal partner derives its nutrition from the photosynthesizing algae. How does a lichen differ in its photosynthetic activity from Elysia chlorotica, the sea slug that’s considered to be a photosynthesizing animal?

Answer 1

The fungi of the lichen relies on the algae for food in order to survive, on the other hand the slug is able to produce its own if necessary.

Answer 2

Lichens can photosynthesize only because of the living algal partner, while Elysia chlorotica incorporates chloroplasts from algae into its cells.