Behavior brief

Gluttonous spiders

Black widow spider
Image: Wikimedia commons, Vesper

Female black widow spiders can become wasteful killers when food is plentiful, attacking prey even when they're not hungry, an unusual phenomenon in the animal kingdom. "They're sort of like humans, when they're around a lot of food they become lazy and wasteful," Arizona State University biologist J. Chadwick Johnson linkurl:told Wired Science.;http://www.wired.com/wiredscience/2011/02/black-widow-gluttony/ "They'll kill food they don't need, and leave some of it uneaten." Female spiders may display this gluttonous behavior to attract mates -- a well-fed female is less likely to eat her partner once they've finished copulating.The stress of monogamyMonogamy has its benefits -- a bonded pair can provide more consistent parental care and such a relationship reduces the likelihood of extra-pair mating. But for those who don't pair up early, finding a partner can be a stressful affair, and once they settle for Mr. Not-Quite-Right, the stress isn't over, according to a linkurl:study published last month in Proceedings of the Royal Society B.;http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2010.2672 Female finches paired with low quality partners, for example, had four times as much of the stress hormone corticosterone than birds with good quality mates.Swimming through sand Scientists studying sandfish lizards, North African reptiles that swim through sand as if it were water, have developed a predictive model of the fluid-like motions of sand and the animals moving through it. The research could eventually spawn better sand-swimming robots, as well as lead to better detection of landmines, earthquakes, and other sub-surface activities. "You can make devices that can sort of wiggle into or through granular materials," study author Daniel Goldman of Georgia Tech linkurl:told Wired Science.;http://www.wired.com/wiredscience/2011/02/sand-swimming-robot/ "We're already talking to NASA about it."

Flowers' mammal lure exposed Researchers have solved the chemical identity of an attractant that a rare parasitic plant species, Cytinus visseri, uses to lure mammalian pollinators. Using a scented Y maze, they showed that striped field mice preferred particular components of the mixture. "Perhaps because it signifies rich food sources or plays a role in communication among mammals," Steven Johnson of the University of KwaZulu-Natal in South Africa linkurl:told BBC News.;http://news.bbc.co.uk/earth/hi/earth_news/newsid_9376000/9376474.stmThe body language of frogs

Red-eyed tree frog
Image: Wikimedia commons, Natox

Red-eyed tree frogs can communicate using whole body vibrations that propagate through the stems and branches of the plants on which they stand. These vibratory messages may alert males of an impending territorial challenge, among other possible functions. (linkurl:Hat tip to Boing Boing.);http://www.boingboing.net/2011/02/09/the-body-language-of.html

Crazy ants, crazy breeding A highly successful invasive insect, the longhorn crazy ant -- so named for its distinctive spastic movements -- has evolved a unique mating system that helps it avoid the genetic pitfalls of inbreeding, which is common in other invasive species. According to a linkurl:study published last month in Proceedings of the Royal Society B,;http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2010.2562 the ants separate the gene pools of males and females. Clonally reproducing queens and males mate to produce the sterile workers, but reproductively active members of the colony are simply clones of their mom or dad, keeping the two sexes relatively unrelated. This allows the ants to successfully establish new colonies all over the world by limiting genetically troublesome homozygosity, which is normally associated with high levels of inbreeding.More women, fewer kids

Original image title: A Mormon "Saint" and wives
Image: Wikimedia commons, DcoetzeeBot

For polygamous Mormon families in 19^th century Utah, more wives meant that each woman tended to have fewer children. While this may equal more children total for men with many wives, it's an evolutionary disadvantage for the women, who averaged one less child for each additional wife her husband married, according to a linkurl:study published this month in Evolution and Human Behavior.;http://www.ehbonline.org/article/S1090-5138%2810%2900120-0/abstract (In the interest of full disclosure, I did my graduate research -- which was on seahorses, not Mormons -- at Indiana University under Michael Wade, a coauthor on this study.)Cats are good nutritionistsEven after thousands of years of domestication, house cats still regulate their consumption of protein, fat and carbohydrates to mimic the nutritional value of their natural prey. Researchers gave more than 100 adult cats three bowls containing food with varying levels of the three macronutrients. Despite the nutritional variability of the food provided, the cats, on average, ate a linkurl:remarkably similar diet;http://jeb.biologists.org/cgi/content/full/214/6/1039 of 52 percent protein, 36 percent fat and 12 percent carbohydrate. "This is a fascinating discovery and we are intrigued to know more about why cats have the ability to do this," lead study author Adrian Hewson-Hughes of linkurl:WALTHAM Centre for Pet Nutrition;http://www.waltham.com/ said in a press release.
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[18th November 2010]