Beavers are one of the few mammals that mate for a lifetime, only choosing to find another mate if their original mate dies. But here's where it gets interesting: there are two types of beavers, European beavers and North American beavers.
In the animal kingdom, mating for life is a rarity. Only 3% of the over 5,000 mammal species are reported to mate for life. The most commonly cited examples include beavers, wolves, gibbons, and prairie voles.
Of the 4,000 or so species of mammals, only a handful of animals have ever been thought to mate for life. This short list of animals includes among others: gibbon apes, wolves, coyotes, barn owls, bald eagles, gorillas and barn swallows.
Some birds who mate for life sometimes even stop eating and die if their partner dies. This is true for geese but also for many songbirds, they have long-term bonds. Which animals do you think mourn the most strikingly?
Animals that mate for life: beavers
Not much is known about how beavers find their mates, but once they do, they stick with that partner for life. A genetic study by Charles University in Prague even found that beavers stay faithful to their mates. Granted, this only applies to European beavers.
We don't often expect moral fidelity from non-human animals, but penguins have long been upheld as an example of romance in the animal kingdom. They commonly pair off to breed and those pair bonds can last a lifetime.
“As it turns out, lobsters don't mate for life,” explained Mr. Wheir, a video editor in New York. Actually, male lobsters in particular are rather promiscuous. “Lobsters do have a monogamous bond, but it only lasts for two weeks,” said Trevor Corson, the author of “The Secret Life of Lobsters” (HarperCollins, 2004).
Gray foxes are also monogamous and mate for life. Gestation period is 53 days and the cubs are born blind and deaf, dark-skinned and almost hairless. They weigh about three ounces and the average litter is four cubs (occasionally five or six).
1. Brown antechinus. For two weeks every mating season, a male will mate as much as physically possible, sometimes having sex for up to 14 hours at a time, flitting from one female to the next.
Could we mate with other animals today? Probably not. Ethical considerations preclude definitive research on the subject, but it's safe to say that human DNA has become so different from that of other animals that interbreeding would likely be impossible.
Bonobos are highly promiscuous, engaging in sexual interactions more frequently than any other primate, and in just about every combination from heterosexual to homosexual unions.
The 'immortal' jellyfish, Turritopsis dohrnii
To date, there's only one species that has been called 'biologically immortal': the jellyfish Turritopsis dohrnii. These small, transparent animals hang out in oceans around the world and can turn back time by reverting to an earlier stage of their life cycle.
In the case of the heart, the overflow of stress hormones can injure the pumping chambers, making them weak and inefficient. It can kill, especially in the case of cautious and high-strung prey animals like deer, rodents, birds, and small primates.
Indeed, some scientists remain skeptical. But a growing number are challenging our species' monopoly on grief. They've identified mourninglike behaviors not just in cetaceans, but in elephants, giraffes, chimpanzees and other primates and, possibly, turtles, bison and birds.
Gibbons. gibbons (family Hylobatidae) Edmund Appel/Photo Researchers, Inc. These agile tree-dwelling apes act like humans in that they occasionally cheat on their mates, sometimes break up, and later get back together again.
Lifelong attachment
In native birds that form long-lasting bonds, including butcherbirds, drongos and cockatoos, differences between the sexes are small or non-existent – that is, they are “monomorphic”.
Bonobos and humans are the only primates to typically engage in face-to-face genital sex, although a pair of western gorillas has also been photographed in this position.
Oral sex has been observed throughout the animal kingdom, from dolphins to primates. Bonobos have been observed to transition from a simple demonstration of affection to non-penetrative genital stimulation. Animals perform oral sex by licking, sucking or nuzzling the genitals of their partner.
It happens in both animals and plants. Such encounters can affect the conservation and evolution of a species. When two different species successfully mate, the resulting offspring is called a hybrid. Hybrids are often, but not always, sterile (think of mules).
Large mammals, such as primates, cattle, horses, some antelopes, giraffes, hippopotamuses, rhinoceroses, elephants, seals, whales, dolphins, and porpoises, generally are pregnant with one offspring at a time, although they may have twin or multiple births on occasion.
Interbreeding between animals of different lineages is widespread in nature—and may reveal some of the mysteries of evolution. Hybrids between brown bears and polar bears—called pizzlies or grolar bears—may become more common as temperatures warm and the species' ranges overlap.
According to Hemanth P. Niar and Larry J Young's study, Genes to Brain to Behavior , it is estimated that only 3% to 5% of all mammal species (excluding humans) form monogamous relationships. And even then, it's complicated.
Guppies. Guppies, a species of fish, are some of the fastest reproducing animals. They are ready for breeding within three to four months and stay ready for their short lifespan of two to three years.
Short answer: no, they can't. They simply don't have compatible parts. (Of course, that doesn't mean they can't be friends: witness Juniper the Fox and Moose the Dog, above). The longer answer to why dog-fox hybrids can't exist has to do with the two species having vastly different numbers of chromosomes.
Foxes scream as part of their mating rituals. Male and female foxes scream to attract a mate. A female fox will scream during the actual act of mating itself. Male foxes scream to mark their territory and warn off potential competitors for mates.