Meet the Air-Breathing Fish with Poisonous Eggs

before this week if i'd had to name one thing that separates the not fish from the fish it would have been breathing air yes there are obvious other differences too like feet but changing the whole system and animal uses to literally take in the molecules that keep it alive feels more important somehow except in working on this episode i learned that sometimes some fish breathe air too and it turns out there are a lot more of them that do this than i had originally thought for example mudskippers these little bug-eyed guys actually breathe through their skin when they're on land yes i said fish on land that is also very weird and how about the walking catfish despite the name they don't actually have feet but they do have an accessory organ that lets them breathe air when they like the mud skippers decide to just leave the water and then there's the lungfish which okay fair enough they have lungs it's in the name i can't really be that surprised about that one what i'm trying to say is if you're an air breathing fish there has to be something else weird about you to make you a bizarre beast good thing gars have that today there are seven living species in the gar family and they're only found in the americas from as far north as southern canada to as far south as costa rica they mostly live in warm shallow freshwater habitats like lakes and rivers but some species like the alligator gar which can grow to more than three meters in length also venture into brackish and salt water and where they live is really important it's what makes their ability to breathe air a useful adaptation instead of just a neat party trick and it might be partially responsible for one of the other strange things about them see you and i we're obligate air breathers we don't have any other way to take in oxygen but gars are considered facultative air breathers they have gills that take in oxygen from the water they're in like a normal fish but when that water is low in oxygen they can surface to gulp air into a specialized swim bladder they have oxygen options and warm shallow slower moving water tends to have less dissolved oxygen in it than cold fast-moving water in fact one study found that gars breathe air more often when the water they're in is warmer so gars can survive in places that other fish ones that only have gills can't and one of the things they do in those lower oxygen places is reproduce female gars lay thousands of eggs at a time and the different species have slightly different preferences about where they lay their eggs for example alligator gar spawn in the shallow grassy floodplains formed when rivers flood their banks long nosegar prefer to lay their eggs in gravely or weedy places in small fast-moving streams and florida gar like weedy backwaters or a shallow pool but one thing that all gar eggs or roe have in common is that they're poisonous but only to some animals experiments where mice and crayfish were fed garrow went badly for those critters and the eggs are also toxic to birds and for humans no gar caviar for us either thanks case reports from emergency rooms on people who have made the mistake of trying it promise nausea sweating vomiting and diarrhea not fatal but definitely not a good time to quote my co-host hank green here don't eat that fish and red eared turtles though don't seem to react to the toxin if they're fed the eggs and the fact that fish aren't affected might have to do with the whole gar air breathing thing mammals birds and arthropods like crayfish can potentially hang out in the kinds of lower oxygen environments that gar frequent but other fish can't so maybe gar eggs are only poisonous to the kinds of animals that have been around to potentially prey on them or it might just be chance regardless it's pretty rare only something like 10 genera of fish out of over 5200 are known to have poisonous rose as for what makes the eggs toxic well researchers seem to only kind of know it's usually just called an ichthyotoxin which means it's a toxin made by fish so not very specific it seems to be slow acting and the amount that's consumed does seem to matter one very weird experiment that applied alligator garrote extract to isolated turtle hearts suggested that whatever the toxin is it somehow messes up the ability of cells to maintain the balance of calcium ions they need to function correctly so it looks like while some turtles can eat the eggs applying the toxin directly to their hearts still goes badly for them and no i have no idea why they tried that the study actually doesn't say just don't eat gar eggs seriously you can eat their meat though if that's something you're into if you can get to it you're going to need something more heavy duty than a filet knife because gar scales are basically fishy armor along with regular bone those scales are also made up of a material called ganowin which seems to be closely evolutionarily related to tooth enamel you know the hardest substance in your entire body guards aren't the only fish with this kind of scale either the sheers also have ganoid scales and like gars they are the living representatives of a really ancient lineage of fish both groups separately split off from the rest of the family tree of fish more than 200 million years ago gars are survivors between the poisonous eggs and the armored scales it's kind of no wonder they've stuck around for as long as they have and what i think is really funny about this whole story of a weird family of fish is that it started off with the one thing they share in common with us the ability to breathe air first off we want to thank dr solomon david for pitching us on these excellent fish and for all of his help with this episode if we've made you a fan of gars subscribe to the bizarre beast pin club and get one for yourself the subscription window is open from now through april 4th if you sign up now you'll get your fantastic gar pin in the middle of the month and the pins after that around the time each new video goes live and if you missed the pin sign up but love weird animals we have other merch you can still get a bizarre beast tote bag and stickers at bizarrebeastshow.com and as always profits from the pen club go to support our community's efforts to decrease maternal mortality in sierra [Music] leone you

Channel: Bizarre Beasts

Views: 289,811

Keywords: hank green, vlogbrothers, bizarre beasts, animals, dftba, weird, enamel pins, pin club, gar, fish, Air-Breathing Fish, Poisonous Eggs, mudskippers, walking catfish, lungfish, alligator gar, eggs, roe, ichthyotoxin, ganoine, Bichirs, ganoid scales, GarLab, Dr. Solomon David

Id: Bcz67-n4GZg

Length: 6min 53sec (413 seconds)

Published: Fri Apr 02 2021