Discovery Channel Exchange

What if HUMANS had sex like WOLVES and went into HEAT and had penises that KNOTTED? We've all read it. Mainstream publications have written articles about it. But there's a whole world of animal sex out there. If you want your blorbos to have sex like kangaroos, ducks, or earthworms, this is the exchange for you. The less like human reproductive sex, the better!

[doitexchange]

FAQ

What even is this? Write a fic of at least 500 words about animal sex characteristics, get a fic of at least 500 words about animal sex characteristics! Unless you mean existentially, in which case we have no idea.

Do fics need to be explicit? No, as long as the animal sex influences the story. It could be about societal expectations around relationships based on reproductive needs, or pre-sex conversation about sexual needs, or marketing copy for a dating app.

Is this about literal animals having sex? Possibly, but not necessarily! You’re welcome to express a preference in your request for the characters as literal animals, or as humans with the reproductive characteristics of your requested animal tags, or anywhere in between. If you do not want literal animals, a literal animal having sex with a literal human, or any other specific combination, please put this in your DNWs as well as carefully considering which freeform tags you request.

Are mythical animals allowed? Yes, as long as the sex is relatively unlike human sex. Were-bear that shifts to hairy-but-human to have sex: nah. Centaur with both human and horse organs that need to be simultaneously stimulated: definitely.

Deets on DNWs Due to the nature of the exchange, the kind of DNWs (do not wants) you might usually use could become confusing. Please be as specific as possible about DNWs, and please do not kinkshame.

Examples of DNWs that are NOT enforceable: “gross slimy animals”, mpreg when requesting animals that don’t fall into a male/female binary, underage without specifying an age or level of development.

Examples of enforceable DNW: spiders, relationships between an entirely human character and an entirely animal character, waste fluids involved in sex, sexual relationship between canon characters A and B.

Example DNWs that probably need more specificity in this exchange:

Bestiality: are two sentient animals ok? A human and a sentient animal? A sentient animal and a non sentient animal? Animals that are sentient but can’t communicate consent?

Underage: Under a specific time-based age, or developmental stage? What about animals that are fully developmentally mature but only a few months or years old?

Gender-based DNWs: are you requesting animals with more than two genders, or sexual characteristics that don’t match with gendered human sexual characteristics?

Opt-out only, nothing is opt-in; if you don’t want it, you gotta list it as a DNW.

Sounds great! How can I learn more? Check out our official AO3 collection!

I have more questions! So do we, for real. But you can contact us on twitter at @DoItExchange or on tumblr at Do It Exchange.

[doitexchange]

Yeager, E. A., J.Pate, G. M. W.Stevens, B.Turffs, and C.Macdonald. 2026. “Hiding in Plain Sight: Evidence of Echeneidae Cloacal and Gill Diving Behavior in Manta Ray Hosts.” Ecology and Evolution16, no. 5: e73548. https://doi.org/10.1002/ece3.73548.

[great-and-small]

Don’t mind me just thinking about the hole in the middle of the United States where Chipping sparrows refuse to fuck

[great-and-small]

[feelingautistic]

The primary method of determining if a shark is a male or a female is by looking for the claspers (pictured above), an extension of the pelvic fins that is only found on male sharks.

[doitexchange]

Tumblr marked this as mature content, therefore it definitely belongs here.

[doitexchange]

lol

[feelingautistic]

The primary method of determining if a shark is a male or a female is by looking for the claspers (pictured above), an extension of the pelvic fins that is only found on male sharks.

[doitexchange]

Tumblr marked this as mature content, therefore it definitely belongs here.

[roxyandelsewhere]

this could change romance metaphors forever

[c-53]

I have a bisexual guppy and its funny as hell to watch because it seems like he’s only bi out of desperation. Like all of the female guppies are unimpressed by him, and dont accept his mating displays, and every time he fails, he goes over to a SPECIFIC male guppy (the prettiest male guppy in the tank) like PLEASE PLEASE PLEASE PLEASE and that male guppy always lets him????

[domnika-deactivated20250923]

i would read that fanfic ngl

[c-53]

About my fish??

[graceful-not]

HELP?????

[everyfandom-girl]

YEAH THIS IS SCIENTIFICALLY RECORDED

WOMEN LOVE GAYBOY

[cadaverjuices]

[mindblowingscience]

A Lizard Laid Eggs And Gave Birth to Live Young In One Pregnancy, In Scientific First

For most animals, reproduction is straightforward: some species lay eggs, while others give birth to live babies.

For most animals, reproduction is straightforward: some species lay eggs, while others give birth to live babies. But our recent research uncovered a fascinating mix between the two modes of reproduction. In an Australian skink, we observed the first example of both egg-laying and live-bearing within a single litter for any backboned animal. This suggests some lizards can "hedge their bets" reproductively, taking a punt on both eggs and live-born babies to improve overall survival chances for offspring.

Continue Reading.

[doitexchange]

'Ghost sharks' grow forehead teeth to help them have sex, study suggests

Male "ghost sharks"—eerie deep-sea fish known as chimaeras that are related to sharks and rays—have a strange rod jutting from their forehea

[doitexchange]

Science | AAAS

[amnesiaguy]

best m/f dynamic is a flamboyant bisexual show-off desperately in love with an extremely practical girl who’s difficult to impress 🤩

[varijacija]

[doitexchange]

These bats copulate for hours with enormous penises but no penetration | CBC Radio

A common serotine bat's penis is seven times longer and wider than the female genital tract. A researcher who specializes in bat reproductio

[mamoru]

if we could speak with lobsters and understand each other I think they might be able to share some really good wisdom as such a long-lived species.

but then I realized. the problem with such a plan

[mamoru]

it seems there are even more problems with this plan than I first thought. learning a lot today

[howdacookiecrumbls]

what was the problem you had in mind

[mamoru]

well compared to those it seems silly now. not to speak for the entire human race or anything here, but the way lobsters communicate is not typically considered ideal.

[zoomane]

oh.

[goryfluff]

Nautilus expedition live streams (+ their commentary) | 2024

[laurelnose]

did you know that the well-known factoid that male anglerfishes degenerate after attachment until they’re basically just a pair of testes is false? i knew of course that they don’t just become “growths” on the female because I’ve handled dozens of attached pairs and every male I’ve ever seen has been very much obviously a whole and complete second fish, but I sort of assumed there was internal degeneration, perhaps muscle atrophy, etc. i can’t believe no one ever corrected me on this but this just doesn’t happen. in obligatorily parasitic species, the male actually continues to grow and increases considerably in size after he attaches to the female, because the two of them can only reach sexual maturity together. me, an octavia butler fan: is this the height of romance??

what is true is that attached males do have hugely enlarged testes proportionate to the rest of their bodies & organs, and that they receive all nutrition from the female’s bloodstream so their stomachs are always empty, though their own gills seem to still be functional, as are their fins and muscles—you can even induce movement and swimming motions on recently dead attached males. I can only assume that at some point someone said that basically the only biological function a male anglerfish needs to perform is sperm production and this got taken out of context and luridly exaggerated over time. he’s not just a pair of testicles! he’s her forever partner! one flesh one end!

[laurelnose]

there’s a type of creature that lives six miles underwater in the sunless void and it’s hatched in two bodies and unless they find each other and fuse into a single chimaeric whole they can never grow up properly. hello? hello??

[savouryduck]

That's extremely cool! also, distracted and enraptured by the writing style at the second link.

[golvio]

Also, it’s basically a full-body tissue graft into conjoined twinhood. Given how tricky it can be for other species of vertebrates to accept donated tissue, anglerfish just doing it like it’s no big deal as part of their lifecycle…actually is kind of a big deal? It certainly raises a lot of interesting questions about how anglerfish immune systems work.

[laurelnose]

it does indeed! the short answer is that the anglerfishes (Lophiiformes: Ceratioidei) who practice sexual parasitism (only maybe two dozen out of over 170 species)[1] mostly don’t have adaptive immune systems anymore, jettisoning anywhere from half to all of the major histocompatibility complex genes and a lot of the code for T and B cell proteins.[2] while it’s not unheard of for modern bony fishes to drop the MHC class II genes for various reasons (pipefish[3], cod[4], a single monkfish[5]), the general trend is for them to have a far more diverse set of MHC class I genes than mammals do[6]. except in the deep sea, where exists a lanternfish (Benthosema glaciale) sans its mhc1u lineage[4] and the ceratioid anglerfishes.

anglerfishes who practice sexual parasitism have a significant contraction of the MHC class I genes and are missing the proteins that let T cells interact with MHC class I molecules, and species that form consortial matings (2+ males, the record is the Queen of the Deep's eight, yeah this is a huge fucking deal from a histocompatibility perspective) also kick the class II genes as well as both rag1 and rag2 (genes whose absence causes the lethal state of severe combined immunodeficiency in mammals).[2] going hypothesis is that they might have hardwired some of the adaptive upregulation of the innate immune system known to occur in rag1-deficient zebrafish[7], which might explain how they don’t drop like flies from all the microorganisms in the abyssal zone[8] but is not a fully satisfactory explanation for the lack of allograft rejection response, given the differences in which pathways get dropped. Ceratias, a monogamous genus, dropped the mhc1u lineage but significantly expanded the mhc1z lineage,[2] so, like... what gives there? (yeah it does fucking kill my friends who actually work in this field that both in situ and in vivo study of this group are currently impossible, on account of the “lives six miles underwater” thing.)

separately, there’s a good chance immune response changes first and sexual parasitism follows afterwards: all the ceratioids have the famous exaggerated sexual dimorphism and all of them perform some form of attachment, but in most of them the male just bites down and hitches a ride for a bit, then lets go and moves on. given the relative lack of nutrients in the deep sea, the evolutionary trend may be for anglerfishes to drop immune infrastructure for metabolic cost reasons and for full-fusion sexual parasitism to arise to take advantage of it, which would explain why 1) sexual parasitism has evolved 3-5 separate times in this suborder[1], and 2) why Vanhöffen’s whipnose, which does not practice sexual parasitism, also doesn’t have a fucking adaptive immune system.[2]

1. Pietsch, T. W. Dimorphism, parasitism, and sex revisited: modes of reproduction among deep-sea ceratioid anglerfishes (Teleostei: Lophiiformes). Ichthyol Res 52, 207–236 (2005).

2. Swann, J. B., Holland, S. J., Petersen, M., Pietsch, T. W. & Boehm, T. The immunogenetics of sexual parasitism. Science 369, 1608–1615 (2020).

3. Haase, D. et al. Absence of major histocompatibility complex class II mediated immunity in pipefish, Syngnathus typhle: evidence from deep transcriptome sequencing. Biology Letters 9, 20130044 (2013).

4. Malmstrøm, M. et al. Evolution of the immune system influences speciation rates in teleost fishes. Nat Genet 48, 1204–1210 (2016).

5. Dubin, A., Jørgensen, T. E., Moum, T., Johansen, S. D. & Jakt, L. M. Complete loss of the MHC II pathway in an anglerfish, Lophius piscatorius. Biology Letters 15, 20190594 (2019).

6. Yamaguchi, T. & Dijkstra, J. M. Major Histocompatibility Complex (MHC) Genes and Disease Resistance in Fish. Cells 8, 378 (2019).

7. Tokunaga, Y. et al. Comprehensive validation of T- and B-cell deficiency in rag1-null zebrafish: Implication for the robust innate defense mechanisms of teleosts. Sci Rep 7, 7536 (2017).

8. Freeman, M. A. et al. Spraguea (Microsporida: Spraguidae) infections in the nervous system of the Japanese anglerfish, Lophius litulon (Jordan), with comments on transmission routes and host pathology. J Fish Dis 34, 445–452 (2011).

[joculine]

diversity win! this spider is forcefemming its prey!

(full article)

[roach-works]

babe wake up new kink just dropped