# What mammal has the largest testicles compared to its overall body size? **URL:** \ **Category:** Factual Questions\ **Created:** [August 23, 2006, 11:06pm UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959 "2006-08-23T23:06:07Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 24, 2006, 4:49pm UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/21 "2006-08-24T16:49:54Z")
Having seen the male rats in the local pet stores, I’m suitably impressed. I can’t imagine anything having testicles much larger relative to body size – they wouldn’t be able to move. I assume you mean largest relative to body in a normal condition. Some people with elephantiasis have outrageously enlarged testicles that certainly does impede motion. ---
**Author:** ![ThisSpaceForRent](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thisspaceforrent/32/345_2.png) [@ThisSpaceForRent](https://boards.straightdope.com/u/ThisSpaceForRent)\ **Post date:** [August 24, 2006, 10:39pm UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/22 "2006-08-24T22:39:06Z")
[QUOTE=Cockatiel] [Tanuki?](http://en.wikipedia.org/wiki/Tanuki) [/QUOTE] Hey…thats the first thing i thought of…read much Tom Robbins? tsfr ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [August 24, 2006, 11:47pm UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/23 "2006-08-24T23:47:56Z")
Welcome to Big Ball City; population: me. ---
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [August 25, 2006, 5:26am UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/24 "2006-08-25T05:26:11Z")
There is a fish species, the male of which attaches itself to a female’s body, links into her blood supply, and atrophies down to being merely a circulatory system and testicles. Consequently the testicles are at that stage the majority of its body-weight. I think that’s pretty much unbeatable, except I have no idea of the name of this species sorry. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [August 25, 2006, 5:30am UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/25 "2006-08-25T05:30:32Z")
[QUOTE=Askance] There is a fish species, the male of which attaches itself to a female’s body, links into her blood supply, and atrophies down to being merely a circulatory system and testicles. Consequently the testicles are at that stage the majority of its body-weight. I think that’s pretty much unbeatable, except I have no idea of the name of this species sorry. [/QUOTE] [Here- Anglerfish](http://en.wikipedia.org/wiki/Anglerfish) > [@](#): > > Some anglerfish have a unique mating method. Since individuals are rare and encounters doubly so, finding a mate is a problem, especially at a time when both individuals are ready to spawn. When scientists first started capturing ceratioid anglerfish, they noticed that all of the specimens were females. These individuals were a few inches in size and almost all of them had what appeared to be parasites attached to them. It turned out that these “parasites” were the remains of male ceratioids. > > When a male anglerfish hatches, it is equipped with extremely well developed olfactory organs that detect scents in the water. They have no digestive system, and thus are unable to feed independently. They must find a female anglerfish, and quickly, or else they will die. The sensitive olfactory organs help him to detect the pheromones that signal the proximity of a female anglerfish. When he finds a female, he bites into her flank, and releases an enzyme which digests the skin of his mouth and her body, fusing the pair down to the blood vessel level. The male then atrophies into nothing more than a pair of gonads that release sperm in response to hormones in the female’s bloodstream indicating egg release. This is an extreme example of sexual dimorphism. However, it ensures that when the female is ready to spawn, she has a mate immediately available.[2] ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [August 25, 2006, 5:33am UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/26 "2006-08-25T05:33:41Z")
[QUOTE=Askance] There is a fish species, the male of which attaches itself to a female’s body, links into her blood supply, and atrophies down to being merely a circulatory system and testicles. Consequently the testicles are at that stage the majority of its body-weight. I think that’s pretty much unbeatable, except I have no idea of the name of this species sorry. [/QUOTE] This occurs in various species of [deep sea anglerfish.](http://www.starfish.ch/frogfish/Deepsea-Anglerfish.html) ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [August 25, 2006, 5:34am UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/27 "2006-08-25T05:34:25Z")
[QUOTE=Askance] There is a fish species, the male of which attaches itself to a female’s body, links into her blood supply, and atrophies down to being merely a circulatory system and testicles. Consequently the testicles are at that stage the majority of its body-weight. I think that’s pretty much unbeatable, except I have no idea of the name of this species sorry. [/QUOTE] [Anglerfishes](http://en.wikipedia.org/wiki/Anglerfish) perhaps? They have an incredible amount of sexual dimorphism and males act as parasites much like you say. Wikipedia is sorely lacking in recording 'nad size, but the male apparently has large testes ([BBC](http://news.bbc.co.uk/1/hi/sci/tech/4666736.stm)). ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [August 25, 2006, 5:43am UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/28 "2006-08-25T05:43:41Z")
Isn’t that the anglerfish family? I think I heard that somewhere… ---
**Author:** ![DrunkOnion](https://avatars.discourse-cdn.com/v4/letter/d/3ab097/32.png) [@DrunkOnion](https://boards.straightdope.com/u/DrunkOnion)\ **Post date:** [August 25, 2006, 7:50am UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/29 "2006-08-25T07:50:11Z")
[QUOTE=Dottygumdrop] [Scylla’s goat](http://boards.straightdope.com/sdmb/showthread.php?t=33909&highlight=goat)! [/QUOTE] great story…them goats got some Nads. ---
**Author:** ![DrunkOnion](https://avatars.discourse-cdn.com/v4/letter/d/3ab097/32.png) [@DrunkOnion](https://boards.straightdope.com/u/DrunkOnion)\ **Post date:** [August 25, 2006, 7:53am UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/30 "2006-08-25T07:53:26Z")
[QUOTE=thelurkinghorror] [Anglerfishes](http://en.wikipedia.org/wiki/Anglerfish) perhaps? They have an incredible amount of sexual dimorphism and males act as parasites much like you say. Wikipedia is sorely lacking in recording 'nad size, but the male apparently has large testes ([BBC](http://news.bbc.co.uk/1/hi/sci/tech/4666736.stm)). [/QUOTE] OK that’s just freaky… ---
**Author:** ![Rune](https://avatars.discourse-cdn.com/v4/letter/r/e68b1a/32.png) [@Rune](https://boards.straightdope.com/u/Rune)\ **Post date:** [August 25, 2006, 12:00pm UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/31 "2006-08-25T12:00:19Z")
There’s some kind of marsupial rat-like creature in Australia which only meets female of the species very occasional. Thus they store up impressive amounts of semen in the testicles for those special but rare occasions. ---
**Author:** ![Spoke](https://avatars.discourse-cdn.com/v4/letter/s/a88e57/32.png) [@Spoke](https://boards.straightdope.com/u/Spoke)\ **Post date:** [August 25, 2006, 2:23pm UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/32 "2006-08-25T14:23:07Z")
[QUOTE=DrunkOnion] OK that’s just freaky… [/QUOTE] Eh. I know some human males who live more or less that same lifestyle. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [August 25, 2006, 3:10pm UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/33 "2006-08-25T15:10:14Z")
[QUOTE=Rune] There’s some kind of marsupial rat-like creature in Australia which only meets female of the species very occasional. Thus they store up impressive amounts of semen in the testicles for those special but rare occasions. [/QUOTE] The Honey Possum _Tarsipes rostratus_, a tiny marsupial that feeds on nectar, is listed by at least one site as the mammal with the largest testes in proportion to body size, but since they “only” amount to 4.2% of body weight, that is exceeded by the bat listed above. ---
**Author:** ![August\_West](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/august_west/32/18069_2.png) [@August\_West](https://boards.straightdope.com/u/August_West)\ **Post date:** [August 25, 2006, 3:41pm UTC](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959/34 "2006-08-25T15:41:39Z")
Boars have big testicles. I don’t know what percentage of their body weight they amount to, but head over to the Swine barn at your local county fair and you’ll see 400lb boars with testicles the size of basketballs. [Previous page](https://boards.straightdope.com/t/what-mammal-has-the-largest-testicles-compared-to-its-overall-body-size/369959.md?page=1)