You are pretty close, actually, the caterpillars have a honey gland, an organ that secretes an amino acid and carbohydrate liquid.The caterpillars secretes the liquid from the honey gland, rather large quantities, enough to feed several ants.But what makes this relationship obligatory for the caterpillar?Well, if the ants don’t feed regularly on the liquid from the caterpillar’s honey gland, the gland overloads and gets infected.The infection will kill the caterpillar and it’ll never reach its final stage of development, becoming a butterfly. John?OK, I just want to make sure I’m following here, the caterpillar needs the ants or it won’t make it to the stage where it can become a butterfly.And the ants do this because they get an easy meal out of it, right?But the ants don’t absolutely need the caterpillar for survival, ‘cause they can get food from other places, right?So it’s still called mutualism even though it seems like the caterpillar’s getting way more out of it.Oh, wait, you said they don’t have to equally benefit. Never mind, sorry.Yes. But there is a type of mutualism where the relationship is necessary for both organisms to survive.It’s called obligatory mutualism. And we’ll talk about that in the next class.
