Adorable Arachnids: The Jumping Spider

Adorable jumping spider.
picture by Kenneth Gilpin at lookingcloser.net

Alright, maybe you're not a spider person. But looking into the big eyes of jumping spider, I find it difficult not to coo. This adorable spider has big eyes, a fuzzy body, comes in a unbelievable variety of forms and colors, and is quite the performer to boot.

But lets start with those big glassy eyes. All eight of them. 

The two big ones in front that give jumping spiders their signature look are unique. They give the jumping spider incredibly resolution, beyond the ability of all other spiders and insects, and even as good as some vertebrates [1]. But such accurate vision comes at the cost of a debilitatingly narrow view. The other six eyes give a much wider view, but bad resolution, a poor substitute for catching prey that is just out of the peripheries.

Many vertebrates have a similar problem which they have usually solved by simply moving their eyeballs, but a jumping spiders' lenses are attached directly to the body, they can't move around. So they have evolved one better, moving the retina itself. Like a camera filming through a window, the retina moves inside the lens. This gives the jumping spider peculiar, color changing eyes; when the retina, the darkest part of the eye, is looking away from you, you can almost see through the lens, making it look colorful. And when the eye is completely black, the spider is looking right back at you [2].

That vision is especially important for the jumping spiders' signature hunting method: jumping. They are able to jump up to 40x their own length, an ability that would let me jump well over 200 feet (is Spider-Man starting to make a bit more sense now?) [3]. Unlike many other spiders, jumping spiders don't spin webs to catch prey, but actively stalk them on the ground instead [4].

The stalking techniques are incredibly complex. Jumping spiders often do not use a straight line to get to their prey as you might expect, but rather circle around, approaching it from a different angle. The problem is that such a rout can take the prey out of sight, and for many invertebrate hunters, that means out of mind [4]. But jumping spiders seem to go far beyond that, able to choose the best path even when it means they may never see their meal again until they get right-on-top of it [5].

Just some of the bright displays that these spiders exhibit.
photo from www.bio.sdsu.edu/pub/spiders/NewFiles/framespg.html

There is more to a jumping spider than just his aggressive side, they are also famed romantics. Male jumping spiders come in a wide variety of bright colors for attracting mates. The peacocks of the arachnid world, jumping spiders come in an astonishing variety of turquoise, maroons, yellows and oranges. The unique coloration can be used to brightly display, or in some cases, deceive [4].

Some species have evolved to become incredible mimics of insects such as ants, beetles and wasps. These disguises help protect them from birds, and other searching predators. Disguises can work both ways however, and some insects have evolved to look like jumping spiders, causing the other-wise hunting spider to back off [4].

No that is not an ant.
photo by Wayne Maddison
Used form the Tree of Life Web Project

But female jumping spiders seem to be particularly picky, and it takes more than just bright colors and disguises to woo them. So males, colors flaring, become tiny flamingo dancers, showing females a variety of dancing moves to show off their prowess. And their dancing repertoire is considerable, including running jumps, body sways and all kinds of leg movements [4]. And to take it one step further, the dance is choreographed to a song all their own.

Jumping spiders may not have ears, but, like Beethoven, they make and hear music by feeling vibrations. Using their abdomen, the males grind away, creating a series of impressive beats while they are dancing. They then put the two separate actions together, making quite the show, all in the name of spider love [1]. 



Sources:

[1] http://www.youtube.com/watch?v=sMa9FdNM5io
[2] http://www.tolweb.org/accessory/Jumping_Spider_Vision?acc_id=1946
[3] http://www.everythingabout.net/articles/biology/animals/arthropods/arachnids/spiders/jumping_spider/
[4] http://www.peckhamia.com/hosted/Richman%20Jackson%201992%20A%20review%20of%20the%20ethology%20of%20jumping%20spiders.pdf
[5] http://www.sciencedirect.com/science/article/pii/S0003347296903723

There is also sooo much more I wasn't able to cover so please check out:

• http://www.tolweb.org/tree?group=Salticidae
• http://www.bio.sdsu.edu/pub/spiders/CaHabro.htm

Photo sources: 

• http://lookingcloser.net/
• www.bio.sdsu.edu/pub/spiders/NewFiles/framespg.html
• http://www.tolweb.org/accessory/Salticids_in_Disguise?acc_id=63

Rattlesnake Feeding

The rattlesnake at my work was recently fed, and I was lucky enough to film it. It's not very good quality and I apologize. My voice is the last one making the obvious statement: "I didn't realize it happened that quick!"

Striker the rattlesnake is one of the many animals cared for at Sacramento Splash. As a baby he was taken from the wild and used as a classroom pet (never handled by the children, obviously). Because he has been in an enclosure and around people his whole life he cannot be released. He was donated to Splash last November after the teacher had retired.

But Striker is more than your ordinary rattlesnake, he's famous. You can watch the CBS spot on him here.

I am now a twitterer... tweeter... I am on Twitter

Hello everyday animal followers, I am increasingly realizing that there is way more information about these animals than I can fit into a single post. So I have created a twitter account to talk about what I couldn't fit into the post, updates and news on upcoming posts, and information on biological discoveries that might reach far beyond what you see every day. So come and follow me, and let me know what you think.

Follow my Twitter: twitter.com/everydayanimal

The Bard's Bird: The European Starling

European Starling

A species is invasive when it is introduced to an area or ecosystem where it did not exist before, and it's introduction causes significant harm to the new ecosystem, or to the local human population. And the European starling is most certainly invasive.

Unlike many invasive and alien species, the origins of the European starling's invasion can be pinpointed down to the date, location, and man responsible. New York City in the 19^th century saw the creation of the American Acclimatization Society (AAC), a group dedicated to the transportation and introduction of European species to North America. The effects of invasive species were not known or fully understood at the time, and acclimatization societies were not uncommon. Many conversationalists and naturalists at the time even supported such societies.

Already having had some notable success introducing European species to New York, such as the house finch, the then head of the AAC, Eugene Schieffelin, set out to introduce every bird that was mentioned in the works of Shakespeare to America. A list of more than 600 species.

Though largely unsuccessful, Schieffelin's introduction of 100 starlings from 1890-1891 became infamous. The European starling's numbers now number more than 200 million and their range stretches across the continent from New York to California, and from Alaska to Mexico. All due to one passage from Henry the IV:

“The king forbade my tongue to speak of Mortimer. But I will find him when he is asleep, and in his ear I’ll holler ‘Mortimer!’ Nay I’ll have a starling shall be taught to speak nothing but Mortimer, and give it to him to keep his anger still in motion.”

The passage refers to the starling's remarkable ability to mimic the songs of other birds, and an individual may be able to produce up to 60 distinct mimics. In addition to their mimicry, starlings are incredibly aggressive towards other birds, often driving away native species that are significantly larger than themselves such as wood ducks and northern flickers. Surprisingly however, this small, bullying bird may not be as damaging as it seems. Though out completing several species, such as the eastern bluebird, a recent study found that many North American birds remain unaffected by this invader.

In fact, the starling's impact on humans may be more severe than its impact on native ecosystems. With an appetite for crops, and able to eat a third of their body weight a day, starlings may cause up to $800 million in agricultural damage every year. They are also known as one of the biggest avian concerns to airplanes.

6% of all bird-airplane strikes are associated with starlings or blackbirds (which often flock together) and in 1960 a Lockheed Electra aircraft taking off from Boston International Airport hit a flock of starlings just seconds after take-off. The engines shut down and the plane crashed into the harbor below, killing 62 people on board.

Although they may be a pest to many, the starlings seem to be here to stay. The U.S. government has spent millions of dollars and many years at failed attempts to control or eradicate starling populations. Poison, artificial hawks, and even blasting starling alarm calls from the roof of the White House has done little to slow starling growth. With such failures, it is little surprise that the European Starling is one of only three species of bird that is not protected by the U.S. government. But with a growing population and flocks that can reach over 100,000 individuals, protection isn't something they need.

Sources:

http://www.news.cornell.edu/releases/jan99/species_costs.html

http://ec.europa.eu/environment/nature/invasivealien/docs/1_EN_resume_impact_assesment_part1_v3.pdf

http://www.nytimes.com/1990/09/01/opinion/100-years-of-the-starling.html?src=pm

https://www.scientificamerican.com/article.cfm?id=call-of-the-reviled

http://query.nytimes.com/mem/archive-free/pdf?res=F50912F73B5B137B93C7A8178AD95F438784F9

http://evolutionarythought.wordpress.com/2011/06/08/a-natural-history-lesson-starlings-and-shakespeare/

http://lib.colostate.edu/research/agnic/starlings.html

http://wdfw.wa.gov/living/starlings.html

http://www.allaboutbirds.org/guide/European_Starling/lifehistory

http://bna.birds.cornell.edu/bna/species/048/articles/introduction

http://www.wbu.com/education/starlings.html

http://www.starlingtalk.com/european_starling.htm

http://aviation-safety.net/database/record.php?id=19601004-0

http://icwdm.org/handbook/birds/EuropeanStarlings.asp

The photo above is from: 

http://evolutionarythought.wordpress.com/2011/06/08/a-natural-history-lesson-starlings-and-shakespeare/

Invasion of the Grey Squirrel

Grey squirrels may seem a dime-a-dozen, but some may be rarer than you think.

The all-to-common eastern grey squirrel

Until recently there were only two species of tree squirrel in California: the Douglas squirrel and the western grey squirrel. Then, at the beginning of the 20th century, the eastern grey squirrel and the fox squirrel were introduced and their populations quickly boomed.

 This boom has come at the expense of the native species. The eastern grey squirrel in particular has a remarkable ability to thrive in urban environments. Any grey squirrel you may have seen in a city, a park, or just around the neighborhood, it was assuredly an eastern grey. Western grey squirrels on the other hand, appear to be the introverts of the tree squirrels. They stay away from cities, towns and almost all kinds of human habitation and stick to California's forests. Because of this, they are quickly losing habit to development where eastern grays, fox squirrels, and humans can thrive.

California is not alone in the eastern grey's invasion. The squirrel was introduced to England in the late 19th century and has since run amok throughout the British Isles. From England they have even managed to invade a peninsula of South Africa.

In England the eastern grey squirrel is considered more than just a pest. Rapidly reproducing and severely out-competing the UK's native red squirrel, drastic steps are being taken to cull the rodent and stop it's spread. Among the most drastic of these steps are attempts to make squirrels into a desirable delicacy.

The idea is to get big-name-chefs, such as Jamie Oliver, to endorse eating grey squirrels in England, and some chefs, like Jimmy Doherty, are even jumping on board. Doherty recently suggesting barbecue squirrel as a summer treat. England's government is also pursuing more straightforward methods, such as a massive cull throughout all of England using poisoned bait.

The unfortunately shy western grey squirrel

In California the damage from the eastern grey squirrels may not be as severe yet, but is certainly becoming concerning. While not yet endangered, the western grey squirrel is listed as threatened in Washington and it's populations continue to decline throughout the west coast.

So the next time you see a squirrel in the park or on the street remember that you are looking at more than a cute, furry, arboreal rodent; you are looking at an invader. And a damn good one too.




Sources:

http://instructional1.calstatela.edu/amuchli/squirrelform.htm
http://home.intekom.com/ecotravel/Guides/Wildlife/Vertebrates/Mammals/Smaller/Grey_Squirrel.htm
http://www.dnr.state.oh.us/tabid/6646/Default.aspx
http://extension.oregonstate.edu/catalog/pdf/ec/ec1572.pdf
http://news.bbc.co.uk/2/hi/uk_news/politics/4835690.stm
http://www.treehugger.com/culture/eat-the-enemy-invasive-squirrel-introduced-as-ethical-food-in-uk-butcher-shops.html
http://www.telegraph.co.uk/foodanddrink/9438410/Jimmy-Doherty-Jamie-Olivers-mate-says-barbecue-grey-squirrel-this-summer.html

Both photos were taken from: http://wdfw.wa.gov/conservation/gray_squirrel/

The Infamous Flea

Adult Cat Flea

The flea has long had a bad reputation. But, unlike many other "pests" I have talked about, the reputation of the flea is arguably deserved.

A common parasite throughout the world,  fleas feed on the blood of their victims; the vast majority of which are mammals, though several species are also known to feed on birds. But they started out feeding on reptiles.

Survivors since the Jurassic, ancestral "giant fleas," probably didn't feed on the small mammals of the time, but rather on warm-blooded, feathered dinosaurs. Only later did they begin to find our ancient ancestors appealing and develop a taste for mammal blood.

And they have been a burden for mammals ever since. As many parasites are, fleas are vectors (transmitters) of diseases like tapeworms and most famously, the bubonic plague. In Europe during the 14th century, the plague, or "black death," devastated the continent's population. Estimates range from one-third, to half of all of Europe died at the hands of the the plague bacteria: Yersinia pestis; A parasite transmitted to Europe by fleas riding on rats from Asia.

A wingless insect, the flea gets around and from hosts to host with its impressive jumping ability. Like Superman, before his writers gave him the cheap ability to fly, fleas can jump over 150 times their own body height. For a 6 foot tall male, that would be equivalent to jumping 900 feet high; almost enough to jump over two Great Pyramids of Giza stacked on top of each other.

There are thousands of different species of flea throughout the world, but the most commonly encountered in North America is the cat flea: Ctenocephalides felis. Despite its name, the cat flea common on both cats and dogs. The good news about this species is that they like your pets, Not you. The cat flea cannot subsist on human blood alone, or at least not without some effort. Given enough time on a human host, an adult may be able to produce viable eggs, but this is rare to say the least.

The bad news is that just because they can't survive on you, doesn't seem to stop them from trying. Humans will often get bit when young fleas leap onto them from the person's pet or carpet. Seasoned adults seem to stick to one host for their entire life, so be warned: If you are getting bit, it means they are multiplying.

Flea larva are identifiable as small, white, hairy worms. Though the eggs are laid on the host pet, they are usually shaken off onto the ground or carpet. Then they hatch. The small white larva luckily do not feed on the blood of unsuspecting victims like their parents, but instead on carpeting or fallen organic material. Soon enough the larva wrap themselves into a cocoon, and wait. And wait. And wait.

Once the larva are fully formed, fleas can go for months without feeding. In their cocoons, fleas can sense the vibrations of an approaching victim, or can  just the carbon dioxide animals breath out, and they time their emergence accordingly. Inexperienced and hungry, the newly emerged fleas will leap for the first warm-blooded creature they sense. Though they will ultimately decide that your feline or canine companions make for better meals, many people suffer from the initial attack. This leaping from the carpet to the host leads to the ankle-bites that many people experience. If bitten, a flea bite should be fairly identifiable. Red, itchy and swollen, the pattern of bites often comes in groupings of three; the disturbing, but aptly named "breakfast, lunch, and dinner configuration."

Sources:
http://www.nature.com/nature/journal/v483/n7388/full/nature10839.html
http://news.bbc.co.uk/2/hi/health/1576875.stm
http://www.abc.net.au/science/articles/2008/01/29/2149185.htm
http://science.howstuffworks.com/zoology/insects-arachnids/flea.htm
http://www.pestworldforkids.org/fleas.html
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7419.html
http://extension.entm.purdue.edu/publichealth/insects/flea.html
http://www.jstor.org/discover/10.2307/2845085?uid=3739560&uid=2&uid=4&uid=3739256&sid=21101615905371
http://delusion.ucdavis.edu/fleas.html

Photo by Ralph Williams at Purdue University.
Photo Source: http://extension.entm.purdue.edu/publichealth/insects/flea.html