Piante e Animali

Physiology

Most Sexes
For some creatures, two sexes is simply too stifling. For example, crustaceans of the genus Tanais have two distinct forms. In one form the males have numerous smelling threads, in the other form males have more powerful pincers to hold the female during copulation. Thus, one type of male finds many females but cannot secure them as easily; the other type finds fewer but hangs on to them with great tenacity. As a result both male types reproduce approximately the same.

The dating scene becomes even more complex in the protozoan world. Creatures in the genus Chlamydomonas, a type of single-celled algae, have no less than 10 sexes. Rather than regard them as "male" and "female", most biologists simply refer to them as mating type plus and minus (mt+ and mt-), and note which plusses mate with which minuses (though they don't have too--all chlamydomonas organisms are perfectly happy reproducing on their own). The record holder for the most number in a species is the single-celled Paramecium amelia, which has eight different sexes. Makes sense--if bisexuality doubles one's chances of getting a mate, just think of how well octosexual critters do.

Most Sex Organs
The ignoble tapeworm, 3,500 species of flattened, intestinal parasites that's the scourge of vertebrates the world over, also has the most sexual organs of any living being. The adult tapeworm has a head, or scolex, equipped with tiny hooks for attachment to the intestinal lining of the host. From the scolex body segments sprout, each containing a complete set of sexual organs, both male and female. Once properly situated a typical worm grows anywhere from a millimeter to nine meters long (0.04 inches to 30 feet) and screws itself over, literally. Each segment mates with itself and grows eggs, which are washed away by the host's digestive wastes. Under the right conditions these suckers can get pretty big: the largest ever found measured over 70 meters in length (230 ft.) and had over 11,000 segments, or over 22,000 individual sexual organs.

Largest Penis
As any rational person would have expected, the largest organisms ever to exist on earth would also have the largest endowments. Among land animals, African bull elephants lead the pack with their 5 to 6 ft. extremities. Whale penises, called dorks (yes, when called a dork in grade school you were actually being compared to a whale schlong), are the largest in the world, the blue whale being the champ with phalli approximately 10 ft. long and 1 ft. in diameter. Its smaller cousins, notably the appropriately named humpback and sperm whale, have penises that measure 9 feet or so. Makes you wonder if this is what Melville had in mind when he chose the title Moby Dick (snicker).

If you measure as a percentage of body length things are a little different. Goose barnacles, with inch-and-a-half-long appendages, rate about 150%. Unbeatable, you think, until you learn that a rare species of Alpine banana slugs (Ariolimax dolichophallus) measure 6-inches long and possess 32.5-inch tumescences, or 542% times their body length. Incredible.

Largest Testes
The largest for land animals belong to, unsurprisingly, the African bull elephant, with testes that weigh around 4.4 lbs. each and encompass a volume of 184 cubic inches—about the size of a large football.

But the REAL hands-down winner is the northern right whale (Eubalaena glacialis), which has a pair of gonads that can weigh up to 2,200 lbs. The enormous size is an evolutionary adaptation caused by a natural phenomenon known as "sperm competition." When the females of the species come into heat, she's immediately mobbed by 30 or so love-starved males who shove one another as they try to jockey into position. When one male finishes (typically this takes 30 seconds), another takes up the slack. And another. The hope of each is to wash out a competitor's sperm with unknown gallons of their own, thereby ensuring that their genes will continue.

Longest Sperm
In most animals, sperm production is much like budget reform proposals: created in great quantities with minimum effort put behind each. But not all creatures follow suit. Drosophila bifurca, a distant relative of the fruit fly, produce sperm 6 cm in length—20 times longer than their entire body length.

Largest Vagina
Belongs to (what else?) the female blue whale, who naturally must park the 10-foot organ of the males. The vulva is basically a long groove along the underside of the female, with a normal length of 6 to 8 feet before elongating to accommodate the male. After coition it expands to some 23 feet in length to hold the baby calf.

Judged as a percentage of body mass, the undisputed winner is the bumblebee threadworm (Sphaerularia bombi). After being impregnated, the female seeks out a queen bee as a host (hence its name). After settling in her uterus and vagina begin to expand, growing until they encompass the entire genital tract, and eventually her entire being—and keeps right on going. I quote from The Natural History of Nematodes (G. Poinar, 1983): "…in Sphaerularia bombi the entire uterus is [expelled] and the expanding organ soon surpasses the length of the nematode. When the uterine cells eventually finish their growth, the reproductive system dwarfs the now moribund female…" The reproductive organs may grow up to 30 times the length of the original female and 300 times the volume, for an overall increase of a whopping 30,000%.

Most Nipples
Out of the 18,000 species of mammals, the tenrac (Centetes ecaudatus), a hedgehog-like insectivore indigenous to Madagascar, has the largest number with 22 to 24 nipples.

Coition

Earliest Sexual Reproduction
Before the onset of sex, the earliest inhabitants of the primordial soup reproduced by fission, meaning they split off clones of themselves by dividing into two daughter cells. While this was great when conditions were favorable, the lack of genetic diversity left the species vulnerable if the climate took a turn for the worse. Sexual reproduction is believed to have originated around one billion years ago, when microorganisms began to fuse with one another to share genetic information. Naturally the smaller, stationary, and starving cells sought after the larger, motile ones rich in nutrients to get the best possible offspring and to last through the lean times; in other words, they were gigolos. The arrival of sexual reproduction enabled a greater variety of organisms to evolve, permitting the development of more complex creatures. Thus, the entire animal kingdom owes its existence to the selfish motivations of a few randy protozoa.

Longest Coitus
Snakes, surprisingly, are the champs in the animal kingdom when it comes to pure sex endurance, no doubt due to the fact the male has a spiked penis, making it difficult for him to escape readily. Typically they remain in union from six to twelve hours. The record is held by a pair of rattlesnakes who remained in copulatory connection for no less than 22.75 hours.

Shortest Coitus
Mosquitoes, which mate on the wing, perform a sex act that lasts only 2 seconds.

Most Copulations
Whether you think of them as cuddly pets or plague carriers, rodents reign supreme when it comes to repeated mating.  I quote from "Copulatory Behavior of Small Mammals" (Journal of Comparative Psychology, v. 39): "In the golden hamster Mesocricetus auratus...copulations may continue for half an hour or more; young males may copulate only a few times, while older ones may attempt copulation as many as 175 times; for adult males, between 65 and 75 copulations per mating may be considered as average."  That alone isn't all that impressive: A type of gerbil called Shaw's jird (Meriones shawi shawi) has been observed to copulate 224 times in the space of 2 hours.

Pregnancy / Birth

Longest Gestation
The Alpine black salamander (Hynobius nigrescens) has an interesting property: the higher the elevation it inhabits, the longer its gestation period becomes. At 4600 ft. or higher the gestation period can last a whopping 38 months.

Longest Daisy Chain