Science Current Events | Science News | Brightsurf.com
 
Email a Friend Send to a friend
Printer Friendly Print In spiders, size matters: Small males are more often meals

In spiders, size matters: Small males are more often meals

September 11, 2008

Female spiders are voracious predators and consume a wide range of prey, which sometimes includes their mates. A number of hypotheses have been proposed for why females eat males before or after mating. Researchers Shawn Wilder and Ann Rypstra from Miami University in Ohio found, in a study published in the September issue of the American Naturalist, that the answer may be simpler than previously thought.

Males are more likely to be eaten if they are much smaller than females, which likely affects how easy they are to catch. In one species of spider, Hogna helluo, large males were never consumed while small males were consumed 80% of the time. This result was also confirmed when Wilder and Rypstra examined published data from a wide range of spider species. Males are more likely to be eaten in species where males are small relative to females.




Much research on sexual cannibalism has focused on a few extreme cases involving sexual selection and sperm competition. However, by looking at data on a wide range of spiders, Wilder and Rypstra discovered that the size of the male relative to the female (often referred to as sexual size dimorphism) determines how often sexual cannibalism occurs in a species. "We were surprised to find that such a simple characteristic such as how small males are relative to females has such a large effect on the frequency of sexual cannibalism," states Shawn Wilder. In many cases, sexual cannibalism may not be a complex balancing act of costs and benefits for males and females but rather a case of a hungry female eating a male when he is small enough to catch. In an interesting twist, evolution does not appear to be driving this relationship. For example, females would not become larger to consume more males because each male would then be a smaller meal to the larger female and males would not become smaller to be eaten more often because they would not get to mate as often. Rather, sexual cannibalism may be a byproduct of the evolution of large females and small males in a predatory species.

University of Chicago Press Journals



Related Spiders Current Events and Spiders News Articles Spiders Current Events and Spiders News RSS Spiders Current Events and Spiders News RSS
Shedding light on the cosmic skeleton
"Matter is not distributed uniformly in the Universe," says Masayuki Tanaka from ESO, who led the new study. "In our cosmic vicinity, stars form in galaxies and galaxies usually form groups and clusters of galaxies. The most widely accepted cosmological theories predict that matter also clumps on a larger scale in the so-called 'cosmic web', in which galaxies, embedded in filaments stretching between voids, create a gigantic wispy structure."

Spider web glue spins society toward new biobased adhesives
With would-be goblins and ghosts set to drape those huge fake spider webs over doorways and trees for Halloween, scientists in Wyoming are reporting on a long-standing mystery about real spider webs: It is the secret of spider web glue.

Scientists discover largest orb-weaving spider
Researchers from the United States and Slovenia have discovered a new, giant Nephila species (golden orb weaver spider) from Africa and Madagascar and have published their findings in the Oct. 21 issue of the journal PLoS ONE.

First 'mainly vegetarian' spider described
The 40,000 or so spiders that have been described are generally known as strict predators, trapping their prey in elaborate webs or hunting them down directly.

Herbivory discovered in a spider
There are approximately 40,000 species of spiders in the world, all of which have been thought to be strict predators that feed on insects or other animals. Now, scientists have found that a small Central American jumping spider has a uniquely different diet: the species Bagheera kiplingi feeds predominantly on plant food.

Researchers go underground to reveal 850 new species
Australian researchers have discovered a huge number of new species of invertebrate animals living in underground water, caves and "micro-caverns" amid the harsh conditions of the Australian outback.

U of T scientists identify gene that has enabled water striders to glide across water
Water striders, the familiar semi-aquatic bugs gliding across the lake at the cottage, have a novel body form that allows them to walk on water.

Researchers to study rebirth of an island after volcanic eruption
When Alaska's Kasatochi Volcano erupted on Aug. 7, 2008, it virtually sterilized Kasatochi Island, covering the small Aleutian island with a layer of ash and other volcanic material several meters thick.

Scary ancient spiders revealed in 3-D models, thanks to new imaging technique
Early relatives of spiders that lived around 300 million years ago are revealed in new three-dimensional models, in research published today in the journal Biology Letters.

Reduced diet thwarts aging, disease in monkeys
The bottom-line message from a decades-long study of monkeys on a restricted diet is simple: Consuming fewer calories leads to a longer, healthier life.
More Spiders Current Events and Spiders News Articles
Are You a Spider? (Backyard Books)

Are You a Spider? (Backyard Books)
by Tudor Humphries (Author)

Did you know that when a spider"s web is damaged, a spider will often eat the remaining silk before making a new one? Young children will make many amazing discoveries about spiders in this captivating account.

MINI SPIDER FINGER PUPPET [Toy]

MINI SPIDER FINGER PUPPET [Toy]
by Folkmanis

Finger Puppet

  Ed Hardy Spider Skull Men's White With Black Band Boxer Brief (L)
by Ed Hardy

Ed Hardy Spider Skull Men's White With Black Band Boxer Brief

Nic Bishop Spiders (Sibert Honor Book)

Nic Bishop Spiders (Sibert Honor Book)
by Nic Bishop (Author)

For the first to third grade set, spiders are fascinating and suitably gruesome, especially when looked at in EXTREME close-up. Amazing images show the beauty and otherworldliness of spiders. Simple, engaging text conveys basic information about spiders as well as cool and quirky facts. One stop-action montage shows a spider leaping twenty times its body length!

Uncle Milton Remote Control Tarantula

Uncle Milton Remote Control Tarantula
by Uncle Milton

It's RC Tarantula! Watch it crawl with real spider-like movement. Its furry texture makes it seem like the real thing! Use the unique spider egg remote control to send RC Tarantula scurrying across any smooth, flat surface. Go ahead, scare your friends and family! Ages 6 and up with Adult assistance recommended.



Spiders

Spiders
Starring: Lana Parrilla, Josh Green, Oliver Macready, Nick Swarts, Mark Phelan
Directed By: Gary Jones



Time For Kids: Spiders!

Time For Kids: Spiders!
by Editors Of Time For Kids (Author)

From deserts to forests to inside your living room, spiders are everywhere! You can spot the sticky webs that they weave to catch their dinners. Spiders can be many different colors and move in surprising ways. Some roll across the sand. Others walk on water!

In SPIDERS!, TIME For KidsĀ® unravels the mysteries of these amazing eight-legged creatures.



Black Onyx Widow Sterling Silver Spider Pendant Charm

Black Onyx Widow Sterling Silver Spider Pendant Charm
by Silver Insanity

Black Onyx Inlay7/8" tall and 5/8" wide3x4mm bail OpeningWeight is 2.5 gramsStamped .925
No chain is included with the pendant
Add a Sterling Silver Chain to your pendant for $5.49 (Save 50%)- available at Checkout in Gift Options

Large Hairy Poseable Black Spider ~ Halloween Spider Decorations & Props

Large Hairy Poseable Black Spider ~ Halloween Spider Decorations & Props
by SeasonsTrading



Go Diego Go Shirts - Spiders Infant/Toddler T-Shirt

Go Diego Go Shirts - Spiders Infant/Toddler T-Shirt
by Ty's Toy Box



© 2009 BrightSurf.com