A True Bug?

I think this is an insect in the order Hemiptera which are collectively known as true bugs. I found it while walking in the Blue Hills today. I don't know exactly what it is but thought it was one of the better photos I've taken in a while.

Plethodon cinereus

Finally! More local wildlife! We find these little guys, the eastern red back (or backed depending on who you ask) salamanders under bricks in our yard through late spring and summer. They were out pretty early this year and I took this photo a few weeks ago. They aren’t the easiest critters to shoot because their little legs are so tiny that they often get lost in the dirt. But they don’t move much when exposed…maybe they’re afraid of giants.

They are widely found in eastern North America: West to Missouri, South to North Carolina, and north to southern Quebec. They have no aquatic larval phase, very unusual for an amphibian, and so have colonized much of the eastern woodlands. Apparently 94% of amphibian biomass in New Hampshire is made of eastern red back salamanders. Not that amphibians are everywhere or particularly hardy creatures but I’m sure there are a fair number of frogs and toads living in NH woodlands.

They are an important part of the ecosystem both as a predator of vast amounts of invertebrate species including centipedes and larval insects and also as a food source for snakes, mammals and birds.

One thing I was wondering, which finally prompted me to do the research for this post, was how they would fair with this strange weather we’re having. It was quite warm for a while and they came out and now it is cold again, even freezing. But unlike many other amphibian species they do not seem to estivate or hibernate. During winter they stop shedding and have special body chemistry that keeps them from freezing. They will burrow underground and feed on insect eggs. Any time it gets warm enough, even in the middle of winter, they will come out to scavenge. So I guess they little guys are probably fine and have just burrowed back beneath the garden. One more headcount in the yard’s biodiversity.

Sources:

uri.edu

eol.org

eNature.com

Animal Diversity Web: University of Michigan Museum of Zoology

The Horseshoe Crab Diaries: Pt. 1 in Which Paul Asks an Expert About Their Eyes

Two nights ago I had a chance, along with several colleagues, to go out to dinner with Bill Sargent who was speaking that night at the Aquarium's Lowell Lecture series. Mr. Sargent is currently a consultant for NOVA, an author and has been the director of the Baltimore Aquarium, a professor and a researcher at Wood's Hole. He was talking about how climate change has affected the community on Cape Cod and so most of our conversation revolved around climate change and how to communicate these issues to the public.

About halfway through dinner, though, one of the senior educators who was there with us turned to me and said "Oh, by the way, Bill is also an expert on horseshoe crabs...so if you have any questions..." As I have alluded (read: expressed firmly and directly) I love horseshoe crabs. I also spend a lot of time with them at work. And the one thing that has continued to irk me is that no one can seem to give me a straight answer about how many eyes they have. So I asked: "Can you tell me how many eyes they have?"

Apparently the true number is 9. Most sources I have read fall into two camps: that they have ten and that they have some unknown number higher than ten. But Bill seemed sure: they have nine. So they would be: two compound eyes, the most recognizable eyes, lateralized on their shells, three "simple" eyes towards the front of their shell (children often think this is the HSC's nose...of course these animals have no nose at all...but they do taste with their feet like many other arthropods), one "eyespot" on the end of the telson (tail) and three "vestigial eyes" on the ventral side (bottom) of their shells. These final eyes were the ones I was the most skeptical about. Really? Why would they need eyes on the bottom of their shell when that part of the body is facing into sediment most of the time?

Well, he had an answer for that too: Allegedly the ancestors to the HSC would spend a lot of time swimming upside down. They used their lateralized compound eyes for directing themselves and orienting towards the bottom but they needed eyes on the bottom because that is where their mouths are and they were hunting surface-dwelling insects. Now, after millions of years of evolution, they are barely functional...but I guess they still get counted.

Sources tell me that they use the three simple eyes to detect levels of UV light which helps them stay in tune with the phases of the moon. They mate and lay eggs at the biggest full moon of the year in late may or early June and so they need to know when that is. Mr. Sargent, though, believes that they actually have a full year long internal biological clock with which they keep time. Because they spend so much time deep under the waves and even buried under the muck they really don't pick up most of the changes of the moon. That actually makes a lot of sense. Perhaps the simple eyes are there for back-up or resetting the clock should it falter.

I was so excited to talk horseshoe crabs with someone who knows so much about them. Hopefully I'll inadvertently stumble into more meetings with people like Bill.

International Weevil Community

Seriously! It exists!

http://weevil.info/

Fothergilla gardenii

A photo of a pretty flower because...it's a nice day and I haven't posted a photo in a while.

Bathynomus giganteus

Bathynomus giganteus, the giant isopod, is quickly becoming one of my favorite arthropods. We have a few molts (the exoskeleton left behind when an arthropod sheds) at the aquarium and I love taking them out to tell people about the crazy creatures that live deep under the waves.

Many of us are familiar with isopods that we find in our yards: pill bugs or rolly-pollies as they are colloquially known are one of the only crustaceans to completely leave an aquatic habitat. There are terrestrial crabs but all of them have a marine larval phase. To my knowledge there are no other crustaceans that can live so far inland. But the pill bug's cousin, Bathynomus is truly giant by comparison and not long ago I was shown this great video illustrating the creature's size and eating habits: it is a truly important part of the sea-bottom ecosystem as it feeds on the decaying remains of large animals. Enjoy!

http://www.youtube.com/watch?v=xeOSXtBCY30

Food Aversion and Chemoreception

I’ve been meaning to look into the evolution of taste and food aversions in response to a question about why someone would dislike eating cucumber, a vegetable that is completely lacking in PTC, the compound found in Brussels sprouts, broccoli and other famously disgust-inducing foods. Frustratingly the two biology text books and the one cognitive science text book in my house have very little information on the senses of smell and taste. I think this is for a few reasons. First, the chemoreceptive senses, taste and smell, are still somewhat poorly understood by science. Second, we tend to favor vision and hearing because these are our “primary” senses which we use to understand our world. Our cognitive world is dominated by vision and audition in a way that makes our chemoreceptive senses seem almost like different things all together.

So the best answer I could come up with for why you would dislike a food that was not bitter is that you have been conditioned. You probably don’t even remember the incidents of conditioning as they more than likely happened in childhood and may have been subtle correlations between food and unpleasant sensations. I know for a fact though that many people are unable to eat foods that they ate when they had a cold, for example. So I imagine that it’s entirely possible to develop a life-long aversion through conditioning. Unfortunately I could find exactly zero information on food texture aversions. I imagine this could also have something to do with aversions to foods that do not contain PTC.

So even though I wasn’t able to find much on anything other than bitter molecule detection at the root of food aversion evolution what I did find was some interesting biological tidbits related to taste and smell. Taste and smell are essentially the same sense in that they are both examples of chemoreception or the detection of molecules and chemicals in our environments. The difference for us is that taste occurs in solutions and smell occurs when we detect molecules floating in the air. But for aquatic creatures there really is no distinction. Because every molecule they come into contact with is in solution they are both tasting and smelling at the same time. Also, for the most part, this is happening constantly. Skates, for example, have nasal passages above their mouths where water is constantly flowing. This allows them to continually monitor what’s in the water.

Another interesting chemoreception fact is that most insects and other arthropods do most of their chemoreception with their legs. This is one of my favorite facts that I share with people about the horseshoe crab but it extends to most other arthropods. They also tend to blur the line between tasting and smelling as they tend to have only one mode of chemoreception. Some can sense with antennae as well as legs and often will have specialized the use of their antennae to things like pheromones or other specific molecules. But the fly, for example, and the horseshoe crab do all their food selecting with their feet.

Hopefully I will find time to write more soon because I have some pretty good photos and want to share some info about salamanders and…more on horseshoe crabs. Let me tell you how amazing they are. Very!