Interesting Science Picture XVIII: Spiders Eat Bats

Call me disturbed.

Spiders Eat Bats (Source)

Figure 2. Bats caught by spiders. A – Adult female Avicularia urticans feeding on a Greater Sac-winged Bat (Saccopteryx bilineata) on the side of a palm tree near the Rio Yarapa, Peru (photo by Rick West, Victoria, Canada; report # 1). B – Adult Proboscis Bat (Rhynchonycteris naso) entangled in a web of Argiope savignyi at the La Selva Biological Station, northern Costa Rica (photo by Mirjam Kno¨ rnschild, Ulm, Germany; report # 14). C – Dead bat (presumably Centronycteris centralis) entangled in an orb-web in Belize (photo by Carol Farneti-Foster, Belice City, Belize; report # 12). D – Dead bat (Myotis sp.) entangled in a web of Nephila clavipes in La Sirena, Corcovado National Park, Costa Rica (photo by Harald & Gisela Unger, Ko¨ ln, Germany; report # 17). E – A bat caught in the web of an araneid spider (possibly Eriophora sp.) in Tortuguero National Park, Costa Rica (photo by Cassidy Metcalf, USA; report # 18). F – Live bat trapped in web of Nephilengys cruentata in a thatch roof at Nisela Lodge, Swaziland (photo by Donald Schultz, Hollywood, USA; report # 47). G – Volant juvenile Proboscis Bat (Rhynchonycteris naso) entangled in web of Nephila clavipes photographed in a palm swamp forest near Madre de Dios, Peru (photo by Sam Barnard, Colorado Springs, USA; report # 7). H – Dead bat entangled in web of a female Nephila clavipes in tropical rainforest in the middle of the Rio Dulce River Canyon near Livingston, Guatemala (photo by Sam & Samantha Bloomquist, Indianapolis, USA; report # 11). I – Dead bat (Rhinolophus cornutus orii) caught in the web of a female Nephila pilipes on Amami-Oshima Island, Japan (photo by Yasunori Maezono, Kyoto University, Japan; report # 35). J, K – A small bat (superfamily Rhinolophoidea) entangled in web of Nephila pilipes at the top of the Cockatoo Hill near Cape Tribulation, Queensland, Australia (photo by Carmen Fabro, Cockatoo Hill, Australia; report # 39). The spider pressed its mouth against the dead, wrapped bat, indicating that it was feeding on it. A Nephila pilipes male also present in the web (K) may have been feeding on the bat as well. L – Dead vespertilionid bat entangled in the web of a female Nephila pilipes in the Aberdeen Country Park, Hong Kong (photo by Carol S.K. Liu from AFCD Hong Kong, China; report # 32).

Social Behavior in Spiders

According to New Scientist a new species of spiders has been discovered that lives in groups and cooperates when hunting:

According to Avilés, there are over 39,000 identified spider species. While she has seen just over 20 species cooperate, she has never encountered any species quite like Theridion nigroannulatum.
The spiders live in nests that house up to several thousand individuals which hunt by hanging threads from low lying leaves. They then hide upside down, beneath the leaves waiting for prey.
When an insect flies into the strands a group of spiders drop down and throw sticky webbing over it. To finish off the ambush they inject venom with their tiny jaws.

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Spiders: One from the Archive

You naughty, naughty people! Come looking for kinky spider lovin ! Come on admit it, thats why you here! Although I have posted some nasty buggers, it’s not that kind of nasty!

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Spiderweb Trapped in Amber

Awhile back I mentioned the discovery of a 120-115 million year old orb weaver trapped in amber. National Geographic and New Scientist both have a story on a spider web trapped in amber. The find dates to about 110 mya.

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Ecology of 30,000,000 Year Old Spiders

Science Daily has an interesting article on spiders trapped in amber. This is a subject I have blogged about previously here. According to the article 671 species of spiders, dating to approximately 30 million years ago, from the Baltic and the Carribean were compared. Here is a picture of one:

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New Species of Assassin Spiders Discovered

archaeid_eating_450w.jpg
According to the California Academy of Sciences nine new species of assassin spiders (such as the one pictured above) have been discovered in Madagascar:

These tiny arachnids in the Archaeidae family are only about 2 mm (less than 1/8 inch) long, but their bizarre fangs and spider-hunting practices have earned them a reputation as the world’s most grotesque spiders. They hunt by stabbing their prey with venom-filled fangs that are attached to the ends of extremely elongated jaws. These specialized jaws are about ten times longer than the jaws of most other spiders their size. To support these long jaws and prevent them from dragging along the ground, Assassin spiders have also evolved elongated necks.

*snip*

Surprisingly, the DNA data also revealed that the presence of elongated necks among Archaeidae spiders had evolved at least two separate times. A classic example of convergent evolution, her findings suggest that the need to strike out at prey from a distance encouraged the evolution of extended body parts on more than one occasion.

Blood Drinking Spiders!

The above is a jumping spider native to Africa:

Evarcha culicivora, is found only around Lake Victoria in Kenya and Uganda. A species of jumping spider, or salticid, it usually hunts insects on tree trunks and buildings. It stalks its prey rather than trapping it in a web.

At the moment it is pretty unique. You see it has a taste for mammal – and human – blood! How do we know this? Scientists recently conducted prey preference experiments. This is how it works:

Lab experiments conducted near Lake Victoria showed the spider preferred female mosquitoes fed with human blood over all other prey, including male mosquitoes, which don’t feed on animal blood.

Tests of the spider’s prey preferences showed it went for blood-engorged female mosquitoes in 83 percent of cases when offered a choice of two similar-size insects.

When it came to making a choice based on smell alone, with the two meal options hidden from view, around 90 percent of jumping spiders selected the blood-filled mosquito.

Although many spiders have relatively poor eyesight—those that use webs to trap prey have no need for acute vision, Nelson says—jumping spiders are an exception.

“Salticids are predators that actively search for prey and mates and typically do not build webs,” she said. “They have evolved eyes that support high-acuity vision suited to their active lifestyle.”

Spiders don’t have the skin-piercing mouth parts needed to feed directly on human blood, but the mosquito-munching jumping spider appears to have got around this. The strategy has other advantages as well, Nelson points out.

“Blood-feeding is a dangerous activity,” she said. “Animals that are bitten have a swatting response, and often the insect is killed.”

So, essentially the spider has come up with a method to avoid being swatted and still specialize on blood.

The study team suspects a blood meal is also biologically important to E. culicivora.

They say spiders expend a lot of energy breaking solid food down into liquid by injecting their prey with digestive enzymes.

“Perhaps blood is a ready-made, nutrient-rich liquid meal,” Nelson said.

Although spiders creep me out, I think this is a fascinating study in evolution. Mosquitos specialize on blood as a food source as does E. culicivora but both have evolved different methods to obtain it. It would be interesting to find out if mosquitos were E. culicivora’s primary prey or if this is a recent addition to their diet. It would also be interesting to see if there is a closely related species that doesn’t feed on mosquitos (I’m thinking of Rhagoletis pomonella).

20,000,000 Million Year Old Spider

The above is a picture of a 20,000,000 year old spider trapped in amber. Sciectists recently created an interesting method for studying the creature – shades of Jurassic Park.

According to BBC News:

Palaeontologist Dr David Penney, of the University of Manchester, found the 4cm long by 2cm wide fossil during a visit to a museum in the Dominican Republic.

Since the discovery two years ago, he has used droplets of blood in the amber to reveal the age of the specimen.

It is thought to be the first time spider blood has been found in amber and scientists hope to extract its DNA.

Even more interesting:

Dr Penney believes it was climbing up a tree 20 million years ago when it was hit on the head by fast flowing resin, became engulfed in the resin and died.

He claims the shape and position of the blood droplets revealed which direction the spider was travelling in and which of its legs broke first.

You can see more images of spiders trapped in amber atMesozoic Arachnids along with other interesting info about Mesozoic spiders.

Black Widow Update

About a month ago I did a post on the Brown Recluse and the Black Widow. I have discovered an interesting article on widow spiders so I am publishing a link to it for those who are interested.

It is in Science in Africa a great online magazine.

The Button Spiders of Southern Africa .

Friday Spider Blogging, Or Poisonous Spiders are my Totemic Animals!

You naughty, naughty people! Come looking for kinky spider lovin ! Come on admit it, that’s why you here! Although I have posted some nasty buggers, it’s not that kind of nasty!

It all started back in the mid nineties. My wife, my two daughters and I had moved out of married student housing (in Knoxville) and were renting a two bedroom house. Along the way we had acquired a kitten, which we named Pounce because he liked to pounce on peoples feet. Anyway, one day a rather mean looking spider comes walking across the floor and stops dead in front of the kitten, who promptly bit it in half. How weird. Several days later I saw another one, then a couple more. Within a week, we were killing about 5-6 a day (normally I don’t kill spiders that wander in doors – usually I set them free – but these were some nasty looking buggers). See for your self:
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Nasty Bugger
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Nastier Bugger

Anyway, one morning I woke up and my inner thigh was sore, started swelling. Every muscle and joint in my body started hurting, I developed a fever. Next day I went to the ER, but after spending eight hours in the waiting room gave up. Several days later I was taking a bath when the swollen area developed what looked like hundreds of tiny white blisters -which burst. After about a month of pain I finally started feeling better. I’m almost positive it was a brown recluse – and have a dead one I caught in a jar that I have schlepped around ever since. Granted, I’m not a doctor, or a spider expert, but it looks identical to the picture. The symptoms I experienced matched some of the lesser known symptoms of a brown recluse bite (the would doesn’t always ulcerate). As mean as they look, Brown Recluses are actually wussies . Apparently, they are quite timid, which jives with the spiders I had in my house.
here , here and here are some interesting references on the brown recluse. Oh, and this one .

Fast forward to the year 1999. we had moved back to Missouri from Tennessee and were on a camping trip in south-central Missouri. My wife and youngest daughter had started to walk down a trail near our campsite when I heard my wife hollar for my daughter to freeze. “afarensis”, she said, (well, okay, she actually called me by my real name)” come look at this. Is it what I think it is?” I walked over to where she was standing and saw:
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Black Widow 1

One of the most beautiful spiders (and one of the only real Black Widow spiders I have ever seen. Disclaimer: I didn’t have a camera that day so these pictures are from the web). There she was, working in her web in all her glory. After a few minutes of looking we carefully went back to our campsite. I resumed my barbecuing and a few minutes later along comes the diminutive male black widow. “Turn around” I told him “Run away, she’s going to eat you after you serve your purpose” Of course he didn’t listen and I found out later that in some species of black widow the female does not eat the male.
Interesting links: black widow phylogeny
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Black Widow 2

So that’s why I say poisonous spiders must be my totemic animal.

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