Polymorphic cannibal toad tadpoles

May 21, 2018 9:30 AM

Spadefoot toad tadpoles are usually gregarious omnivores who spend time together chewing organic detritus on the pond bottom. But if they get the right kind of food, and maybe some help from their mothers, they turn into big, sharp-beaked, solitary carnivores. The carnivorous morphs love shrimp, but they're also happy to eat other tadpoles. If they're not too hungry, they'll take a nibble of the other tadpole first to make sure they're not eating a sibling.

With thanks to Drosera for telling me about these.

posted by clawsoon (10 comments total)

Biology is so cool and weird.
posted by tobascodagama at 9:53 AM on May 21, 2018 [1 favorite]

Metafilter: spend time together chewing organic detritus on the pond bottom.
posted by Vesihiisi at 10:02 AM on May 21, 2018 [7 favorites]

Fascinating. I skimmed the paper from the last link and they only hypothesize on how tadpoles discriminate kin from non-related same-species (conspecifics) tadpoles. They hand-wavy something about smell.

Here's another paper (2000, low impact), in a different species of tadpole, that tries to explore how kin recognition works, but no mechanism is given. But prior exposure to kin is not required for recognition.

This 2007 review suggests familiarity/ exposure or (hand-wavy) "phenotype.".

Another 2009 paper, but again, no mechanism discovered.
posted by porpoise at 10:28 AM on May 21, 2018 [4 favorites]

I may be nearsighted but thanks to glasses, I never have to bite someone to check if they're related to me
posted by mlo at 12:06 PM on May 21, 2018 [1 favorite]

Sorry, but my favorite frog/toad will always be Kermit (YAAAAY!). With a proud runner-up of Andy Devine's Gremlin Froggy.
posted by oneswellfoop at 3:19 PM on May 21, 2018

oneswellfoop: Sorry, but my favorite frog/toad will always be Kermit (YAAAAY!).

Y'know, I've never seen Kermit with another frog.

Makes you wonder if he got hungry.
posted by clawsoon at 4:58 PM on May 21, 2018 [2 favorites]

He didn't eat Robin! But then, Robin *is* a relative...
posted by tavella at 8:28 PM on May 21, 2018 [1 favorite]

Kermit's Swamp Years Eating Your Dinner.
posted by porpoise at 8:39 PM on May 21, 2018

Another tadpole fact is that the Norwegian word for tadpole is rumpetroll which literally means butt-troll. Use it for good.
posted by Vesihiisi at 3:40 AM on May 22, 2018

We had these little buddies in the Southern Colorado high desert. It always seemed magical that they'd just . . . appear after a heavy rain, sing until it dried up, and then burrow back down into the dirt till next time.
posted by aspersioncast at 4:57 AM on May 22, 2018