Instead of writing my own post this week, I’m going to link you to a post about one of the coolest things I’ve learned about in months: microhylid frogs and tarantulas may have a defense mutualism! Frogs living and breeding in the same holes with tarantulas may be protected from predators, and tarantula eggs may be protected by frogs from ant predation or parasitism. HOW DID I NOT KNOW ABOUT THIS UNTIL NOW? Please read every amazing detail here. You can also see some cool photos of spiders and frogs hanging out together here. Also, someone already posted a relevant cartoon to Imgur: enjoy!
Parasite Ecology
Short summaries and cartoons about parasite-themed research
Parasite Ecology 
Thanks for highlighting this; when I reviewed the literature about a decade ago, mutual physical defence interactions didn’t seem to figure at all. In fact I was wrong and Fig. 18.2 in the following chapter is incorrect and anemone-anemone fish should have been included in that category. Now the frog-spider relationship is another example that we can add; the matrix is starting to fill out…! http://oldweb.northampton.ac.uk/aps/env/lbrg/journals/papers/OllertonBarter.pdf