Hello.

I’m going to post things.

-Lauren

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Cool Pets: Malaysian River Prawn

Yum

If you have ever been to a Thai restaurant and read the menu, you might have come across a dish containing river prawn. This prawn is known as the Malaysian river prawn, or Giant river prawn; scientific name: Macrobrachium rosenbergii.

Macrobrachium” refers to the extreme enlargement of the second pair of pereiopods (walking legs also used for gathering food).

Their life cycle is pretty interesting. Like some other shrimp species, including the Amano shrimp, the larvae require brackish water to survive. When they become juveniles, however, they move into freshwater to live the remainder of their life. This particular detail made it difficult to raise them in captivity as a food source until someone figured out the larvae need brackish water to survive. Now, they are raised in huge numbers as food.

I have recently acquired several juveniles, and although they may be “shrimpy” now, I’m excited to see how big they get! Here are some pictures of them for you enjoyment:

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For now, they are content to scavenge the leftovers from my fish and snack on a few crab wafers.

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These little guys are already pretty feisty, waving their enlarged pereiopods around just like my crayfish. I’ve read they get even more aggressive than crayfish…sweet!

I’m hoping that at least one of them will make it to the “blue claw” stage. So cool looking!

Stay tuned, as I will post more pictures as they continue to grow.

Garter Snakes: she-males?

Come again?

In short: female mimicry to increase one’s fitness.

Let me explain. Every winter, garter snakes hibernate underground in massive groups. (Not unlike the snakes in the cave in Indiana Jones: The Raiders of the Lost Ark…they are virtually harmless, though.)

When the time comes to emerge from their den, they emerge at roughly the same time and start mating. Now, males that have just come out of hibernation don’t act, smell, or “taste” like males at all. In fact, they look exactly like females…except for the fact they are males. We will call these “she-males”. (an article in Nature called them that, so I will too)

The she-males secrete the same chemicals as females, make the same movements as females, and even try (very successfully) to get normal males to mate with them.

Oddly enough, this she-male state is only temporary. After a while, the she-male returns to a normal male and he goes off and mates with a female…hopefully a real one.

So why on earth does this happen?

There are several possible reasons:

  1. Males are aggressive towards other males, so by masquerading as a female, the she-male avoids potentially dangerous situations.
  2. The male may be confused by the she-male, and thus the she-male may get better access to the mating ball while the poor normal male is trying to mate with non-females [1].
  3. Males (of this species) don’t have unlimited “resources”, so a male who mates with a she-male wastes his resources and therefore his chances of producing young…and possibly gives the she-male the chance he could have had.
  4. The third reason ties in with this: Males aren’t ready to mate immediately out of the den, so they bide their time getting other males who have been out longer (and are ready to mate) to waste their resources while they prepare their own.

Basically, this she-male state is a way to increase the fitness of the individual.

Note: Fitness does not refer to strength or health in this case; rather, the number of offspring of an individual who survive to successfully reproduce.

Really interesting stuff. Wish I could find a video about this…

Video

The Lyrebird: the ultimate copycat

This is an example of extreme mate selection in birds. Just watch.

The only other bird I can think of that does this is the mockingbird. My senior high school biology teacher told us about a mockingbird that lived in a nearby tree who mimicked the beeps from the garbage truck going into reverse. Needless to say, my teacher jumped out of bed in a panic on occasion, thinking she forgot it was trash day.

 

Why are there so many bugs around my porch light?

I’m sure all of us have looked outside in the evening at our porch lights and cringed at the sight of what seems like hundreds of flying insects hovering around and/or crashing into the light, over and over. Some of them (June beetles, especially) are left on their backs on the ground, trying desperately to right themselves. And then, you spot other animals hanging out on walls nearby, just basking in the glow of your porch light. (like geckos or spiders)

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These bugs seem to turn into robot zombies when they see the light and spiral closer and closer until they ram into it…and then keep on ramming into it like a drunk.

bug light

What is up with this?! It’s pretty annoying…(unless you’re an entomologist trying to collect bugs for study)

There are several theories floating around, but the one that makes the most sense is the idea that moths and many other nocturnal flying insects use transverse orientation to “navigate”.

Transverse orientation is

“keeping a fixed angle on a distant source of light for orientation.” [1]

Usually, nocturnal insects have a distant yet intense light source that they set at a certain angle in their field of vision to maintain a certain direction of flight: the moon. This allows them to travel in a somewhat straight line (the moon rises and sets, but it works well enough) and not end up flying around in circles. (This is much like using the north star for navigation, which doesn’t rise and set)

night light will reichelt

“Night Light” Will Reichelt

However, there are artificial “moons” we make that throw the insects off: artificial light bulbs and even camp fires. These light sources look like the light coming from the moon in many cases, so insects lock onto them and try to use them as a guide.

The problem: Let’s say you put a light source  in the right side of your field of vision and try to keep it in the same place as you fly. If the light source is not on the same planet as you, it helps you maintain a steady direction and you’re happy.

The problem arises when the light source is on the same planet as you…and is actually fairly close to you. When you try to maintain the light on your right side, you’re going to end up flying in circles around it, getting closer and closer. Basically, you’ll end up spiraling into it and hitting the bulb or flying directly into the fire…which is exactly what happens to the unsuspecting insects.

When they run into the light source (literally), all havoc breaks loose and they seem to have no idea what is going on. They can even hurt themselves, especially if the light bulb is really hot (…or is fire) or there are electrified wires surrounding the bulb. ( <–sneaky)

Now, not all light bulbs attract these poor fellas. The light has to be intense enough and enough like the moon’s light…which is reflected sunlight, so it will have UV light as well. So, bright white lights and blue lights are the ones that are going to attract the most bugs, especially if they produce UV light. Lights with a longer wavelength (such as yellow) are not going to attract bugs as well, if at all.

I can personally vouch for this, as I was having a hard time collecting nocturnal insects for my entomology class because our porch light is yellow…I resorted to using an LED light, which worked, but I think our apartment management pretty much killed off most of the insects in the apartment complex; I only caught one lacewing.

Note: A good way to catch a lot of insects at night is to take a flashlight and a white sheet out to a field or park and get someone to turn on and hold the flashlight behind the sheet. Bugs will come flying and land on the sheet, and all you have to do is slide them off into your container.

spider web

As for the geckos and spiders chilling around the light, you don’t need to be worried for them; they’re getting the easiest meal of their life. Although, they are probably being stalked from the shadows by bigger things that will eat them, so maybe they do need to be worried…

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Daddy Long Legs: Most poisonous spider?

Have you ever heard this?

“Daddy Long Legs are the most poisonous spiders, but they can’t hurt you because their mouths are too tiny to bite you.”

opiliones

If you have, you need to read the rest of this post to be able to combat this kind of ignorance, because that statement is so false it’s ridiculous.

Here’s why:

  • Daddy Long Legs aren’t spiders. They belong to the Order Opiliones, in the Class Arachnida, and are more closely related to scorpions (Order Scorpionida) than spiders (Order Araneae).

Arachnida

They don’t even look like spiders…

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You can see how the cellar spider on the left has two parts to its body (cephalothorax and abdomen), while the daddy long legs on the right has a single body segment. (the cephalothorax and abdomen have been broadly fused)

  • Daddy Long Legs don’t have fangs. Even if they had fangs, their size wouldn’t matter. Extremely small needles can still pierce skin, and that’s what fangs are: hypodermic needles.
  • Daddy Long Legs don’t produce poison or venom. Even if they did, they don’t have the equipment to deliver venom.
  • Maybe they’re talking about the Daddy Long Leg spider? (cellar spiders, grandaddy long leg spider, etc.) Nope. This spider is definitely not the most venomous spider. They do have really small fangs, but that doesn’t prevent them from biting.

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Anybody know how this myth started? I’m stumped…

Note: The terms, venomous and poisonous are not synonymous. The term, “venomous”, means the organism produces toxins that it delivers to prey. Venom is usually a sign of a predator. The term, “poisonous”, means the organism produces toxins that it doesn’t actively deliver to another organism. (ex: most frogs are poisonous) Poison is a defense mechanism.

Also, Daddy Long Legs do possess chelicerae (modified appendages usually associated with feeding), but they don’t have fangs on them. Fangs and chelicerae are not the same thing.

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