Michael Baird, Wikimedia Commons
Does it pay to be a lover or a fighter? The answer can depend upon the situation, of course, but some animals have evolved a greater tendency to war or woo, suggests a study in the latest issue of Nature Communications. Senior author John Fitzpatrick, a lecturer on animal evolution at The University of Manchester, and his colleagues studied over 300 species and found that elephant seals are definitely more fight-prone. "In groups like pinnipeds, in some species, like elephant seals, males are able use their investment in weapons -- in this case extremely large body size -- to keep rival males away from females and there is a trade off between investment in testes and weapons," he explained. "Essentially, the largest pinniped species have the smallest testes, i.e. they are fighters, rather than lovers."
U.S. Fish and Wildlife Service
The walrus is another pinniped that is more brawn and blubber than love machine. Both males and females use up a lot of energy sustaining their big bodies and tusks, which they aren't afraid to use in battles.
Acanthocephala is a group of parasitic worms, according to Fitzpatrick. As if that is not unattractive enough, these worms spend most of their energy in maintaining their body spines and fighting. This is arguably the most un-romantic group of organisms in the animal kingdom.
Dick Daniels, Wikimedia Commons
Male pheasants "invest in both fighting and sex," according to Fitzpatrick. "It is quite costly to invest in everything. You don't get something for nothing in evolution," he said. Nevertheless, there are some animals, like pheasants, which seem to have evolved an even investment in the anatomy and behaviors required to fight and mate. Male pheasants that invest in being large fighters, for example, also develop large testes.
These tiny fish are scrappy, but sexy sometimes too. As for pheasants, male minnows are hard-wired to invest in fighting, often with their strong fins that push waves of water against rivals, but also in procreating. Male minnows often turn bright red or orange to attract females, and then go to a lot of trouble to find the perfect spawning site.
Johan J. Ingles-Le Nobel, Flickr
Male bush crickets have the largest testes compared to body mass of any known species on the planet. Males fight a lot too, though. In China, "cricket fighting" is viewed as a spectator sport on par with bullfighting and cockfighting. Cricket fights are even arranged according to weight class, with human viewers betting on which cricket will win the match.
Moses, Wikimedia Commons
Humans and other primates wind up in the category with crickets and minnows. Our canine teeth and other features can be used in fights, but significant bodily energy often goes into wooing too. As Fitzpatrick said, "Compared with our primate relatives, human males don't exhibit particularly large investment in either weapons (which we measured as the difference between male and female body sizes) or testes size."
Albatross couples romantically dance and spend their entire lives together, devoted to a single, adoring mate. Males will wait for days, sometimes weeks, for their partners to arrive at mating sites.
Jangle1969, Wikimedia Commons
Some snails are hermaphrodites, having both male and female sexual organs, but most still need a partner in order to reproduce. Ronald Chase, a professor of biology at McGill University, found that garden snails court anywhere from 15 minutes to six hours. It's a sexy tease that involves a lot of lip and genital nibbling. Like a natural cupid, one snail then builds up hydraulic pressure that causes the release of a sperm-containing "dart." The result is that these creatures spend a lot of time procreating, as most gardeners have probably figured out.
Lovebirds (birds in the genus Agapornis) aren't always loving around strange birds and humans, but they are completely devoted to their mates. They may spend their days preening, dancing and cuddling. Mating can occur, on and off, for several days at a time during the breeding season. Some lovebirds are endangered in the wild. Black-cheeked lovebirds, for example, are among the most endangered of all African parrot species. "Understanding the ways animals reproduce is important as it helps us understand how species evolve and can prove important for conservation," said Fitzpatrick.
Scorpions are master architects, constructing homes that include both a sunning platform and a cool room that retains humidity, according to new research.
The findings, which will be presented Thursday, July 3, at the Society for Experimental Biology’s annual meeting, prove that homes built by animals other than humans can be incredibly comfy and functional, even when they're located in extreme environments.
Scorpion homes have never before been seen in detail, given that they’re located underground and require special equipment to investigate. Also, few people want to hang around scorpions for long, given their formidable stingers. But Amanda Adams, of Ben-Gurion University of the Negev, was up to the challenge.
Adams and her research team began by carefully trapping large-clawed scorpions (Scorpio maurus palmatus) found in Israel's Negev Desert.
Next they prepared replica casts of the scorpions’ burrows. To do this, the researchers filled the burrows with molten aluminum. When the casts solidified, they were removed and analyzed with a 3D laser scanner and computer software. The scientists were then able to see how sophisticated the burrows were.
Each burrow began with a short, vertical entrance shaft that flattened out close to the surface. This flat area, a sunning platform, allows the scorpion to safely warm itself before going out at night to forage. (The researchers explained that scorpions are ectothermic animals, meaning they rely on energy from the environment to regulate their internal body temperature.)
Beyond the sunning platform, the burrows turned sharply downward, descending farther below ground until they reached a dead-end chamber -- a cool, humid, comfortable place for the scorpion to rest during the day, with minimal evaporative water loss.
Because all of this architecture is underground, a person could walk right over the tiny entrance hole and not realize that they are standing on top of a miniature, scorpion-built mansion that perfectly satisfies the builder’s needs.
"Very little is known about burrow environments," Adams said in a press release. "We plan to expand our studies to more scorpion species around the world, to test how burrow structure is shaped to be part of the burrow builder's extended physiology."