Tarantulas!

When most people think of spiders, the first thing that usually comes to mind is the tarantula. Its big, its fluffy...its fierce. Because of its large size, it is one of the most commonly used spiders in movies, TV, or commercials. If you ever seen the movie Indiana Jones, you'll remember the scene in the opening of the film where Indy and his assistant get covered in tarantulas going for the Golden Idol. Or, if you've seen Arachnophobia, where they fall from the trees during a scene canopy fogging and are used profusely in the movie trailer.

  Tarantulas are even so well known that they have their own movie, made in 1955 and bears their name as title. For more information about this movie, check out the IMDB site here.

    All of these movies take advantage of a human's innate fear of spiders, which has been actually found to be partially genetically based. A study at the anxiety disorder clinic at Sydney University in Australia found that some fears, like fears of snakes or heights, might be genetically inherited to prevent us from harm. Super big spiders, like tarantulas, are some of the strongest triggers for this fear if you have it, and that is why they are used so frequently. They super-size the shock!
    However, not everyone has an inherent fear of tarantulas, and they are really not as fearsome as people would like to believe.  For their large size they are really fast runners, especially when they are running away from something scaring them. Their bite will not kill humans (unless you are allergic to them), and for most of the time they hang out hiding in their webs on the ground. Tarantulas can be found in lots of places across the world, but mostly in desert areas and the tropics. Because they also can be fairly attractive spiders, ranging from pink haired ones to blue, they can also be popular pets. They mostly feed on insects, though some larger spiders in the Old-World tropics have been recorded catching birds and other vertebrates!
     Here in Oklahoma, though, the native tarantulas are mostly brown. This past weekend I was in Black Mesa with the Mammalogy department and found this male tarantula crawling around looking for a female spider. In the fall many male spiders go out in a massive "migration" to look for females.

Male tarantula from Black Mesa. You can tell its a male because of the "fat" pair of structures that look like legs in front of its head area, called the pedipalps.

 Many tarantulas in the tropics are also brown too. This spider I found near a 2000m site in Costa Rica where I was helping to sample frogs.

Smaller, female tarantula from Costa Rica. Note the darker coloration of the "head" (cephalothorax) area

     While I don't suggest you pick up a wild tarantula to put on your hand for a photo like I did, its important to note that these spiders are actually pretty mellow and nothing really to fear! If you don't threaten them, they don't threaten you, and they are doing their own thing. If you were born without a fear of spiders, I encourage you to check these guys out because they are a really neat group of spiders.
      If you'd like more information about tarantulas, check out this nice fact sheet! Have a good one everyone!

Let's see if you can solve a riddle.

What can be as small as the head of a pin, or as large as a desk, lives in the sea (but also sometimes in fresh water!), has no brain, but can kill a human? 

Do you have a guess?

That's right, it's a jellyfish! Despite the potential danger of these invertebrates, jellyfish have an almost hypnotizing, soothing quality about them when they swim in a tank, and can be very beautiful as well. 

Jellyfish (phylum Cnidaria) come in many different colors and sizes. Most everyone knows that they live in the oceans, but there are also some freshwater specimens as well - even in Oklahoma!

The squishy-looking "jelly" part of the jellyfish is called the bell, and it is mostly made up of water. There is a thin layer of skin on top of the bell, which is where the nervous system is located. But since jellyfish have no brain, they also don't have a central nervous system. Their nervous system is called a "nerve net." Jellyfish also do not have eyes, but some have ocelli, which can detect light. You might remember ocelli from other entries - many insects have ocelli instead of eyes as well. 

Not all jellyfish stings are harmful to humans - in fact, many are so slight that we would never even if a sting occurred. Jellyfish sting by a type of stinging cells that they have on their tentacles, called nematocysts. These are used to kill fish or other small animals that are unfortunate enough to get entangled. Jellyfish do not actively hunt their prey - they simply eat whatever swims through and is stung in their tentacles. They have a "mouth" under the bell, and a simple or "incomplete" digestive system in that they expell wastes through that same hole. Many other invertebrates have this same sort of digestive system. 

Large jellyfish populations can be a sign that the habitat they're living in is in trouble. Too many jellyfish can be a sign of overfishing. They can take over the ecosystem they're in, essentially choking out other marine life. 

Jellyfish washed ashore in CT

Isn't that one beautiful? It almost looks like a flower. My sister spied this one and took its picture for me.

Happy Friday everyone!

COME TO THE LIGHT!!

A Bugs Life is one of the most popular digitally animated movies about insects. It was made in a while ago, in 1998, but still remains a classic despite the digital film advances since then because of its witty humor and detailed observations about insect life. One classic joke is when Flick the ant, the main character, arrives at the insect "city" and encounters other types of insects. His arrival at the city opens with two insects being drawn to a bug-zapper light, with one warning the other "don't look at the light!!" as his partner slowly swirls closer to it, exclaiming "I can't help it!!" as he get zapped.

Don't look! Image from http://www.kwaree.com/blog/wp-content/uploads/2007/05/bug-zapper.jpg

    The reason everyone laughs at this joke is because almost everyone knows that many insects are drawn to artificial lights at night. This is why bug-zappers work, and why you'll find a pile of dead insects under your porch light [or in your porch light, if its not sealed correctly!]. Its so ubiquitous in our culture, there even is an iPad app for bug zapping. Even before electricity insects were noted for being drawn to candle light. If you search on Google for "Poem, moth, candle" you get over 1 million references for poems about moths being drawn in a death waltz with a candle flame. So, why are insects drawn to the light that it makes it an effective trap?
     Many insect groups are drawn to light because of a property called phototaxis, which is an organisms to or away from light [photo=light, taxis=movement]. Many insects are actually negatively stimulated by light, and run to darkness. Cockroaches are a good example of this...turn on a light in a room full of them, and they go hide. Most other insects, however, are attracted to light, especially at night. This is because many groups of insects, especially flying insects such as Lepidoptera (moths) and Diptera (flies, mosquitoes) use the moon for navigation at night. Before electric lights and other artificial lights came about by humans in the last couple of centuries, moon light was the strongest light source available at night. By using the light to orient themselves, they could migrate, and find new habitats.

What the insects adapted to use to navigate, until we hijacked their system. Flynn, Texas

    The way the phototaxis works is one sensor on the bugs (often the eyes) gets the information from the light as wavelengths, and the insect then turns in the direction of the source of the light so both sensors or eyes get the same amount of light. This turning towards the direct of the light causes an insect that passes the bug zapper to pick up the light information, turn towards it, then slowly keep getting in closer. It keeps getting closer and closer with tighter circles around the light, until its zapped by the light's electrical current. Using just light, and not the zapping part, many entomologists can draw in insects to observe their behavior and collect specific ones that they need to study (this is called spot lighting, UV lighting, or using light sheets), and leave the other insects they are not interested in alone.

Fellow entomologists being creative by using a white garage door as a "light sheet"

      While bug zappers are effective at killing insects, its often effective at killing both "good" AND "bad" insects. Most people purchase bug zappers to kill mosquitoes, which are annoying due to their bites and dangerous because they can transmit diseases. However, bug zappers are effective at killing insects like moths which are good pollinators in some cases, beetles that are good predators of garden pests, and various other insects that happen to use the moon to navigate in their otherwise harmless lives.
    So, the lesson here? Before humans brought artificial lights, many insects used the moon at night to navigate. However, when we brought in much brighter light sources that are actually within reach of the insects in flight, we were able to take advantage of it for trapping them and studying them. Next time you see bright light at night swarming with insects, come to the light yourself and see what other six-legged friends are drawn to it. Have a good week!