Meet the Tank: Sea Stars



Science Museum of Virginia sea stars



By Meghan West

Gallery Educator

Science Museum of Virginia

In our “Beach Science: It’s a Shore Thing” exhibit we have a saltwater tank housing some sea creatures that can be found off the coast of Virginia. For those of you who have been to “Beach Science: It’s a Shore Thing” you may have already seen or even touched one of our sea stars. For those of you who have not, let me introduce you.

Sea stars, formally known as starfish, were renamed because they don’t look like a fish, don’t swim like a fish, and are not a fish. Because of this they dropped the name fish and added sea (same thing happened to sea jellies, formerly known as jellyfish). They are in the phylum echinodermata, which means spiny skin and anyone who has touched one or even handled a dead one can feel the bumpy, spiny skin. They are in the same phylum as sea urchins and sand dollars, even though they don’t look a lot alike.

Strange creatures are our sea stars; they have no blood, no brains, and if we chop them up, as long as there is a fifth left, they will grow everything back. As for the no brains thing, anyone who has seen “SpongeBob SquarePants” can attest that Patrick Star, SpongeBob’s best friend, is not the sharpest knife in the drawer. Comedy is not the only reason Patrick is a little slow on the uptake. The creator of SpongeBob, Stephen Hillenburg, taught marine biology at Orange County Ocean Institute in California and puts weird facts like that into the story and characters. Sea stars actually have something going on upstairs, but it’s just a nerve ring instead of a brain.

Breathing is another thing that our dear sea stars don’t do like most of the creatures we come in contact with. They absorb sea water through a small dot normally located somewhere on the top facing side of the sea star; this is called a madreporite. The water they absorb is used in their circulatory system (yes, you read that right, sea water being used for blood). While they have the water they might as well make the most of it and absorb the oxygen out of it.

For vision the sea star uses a tiny dot on the end of each arm to see. If you find a sea star large enough you may notice the tiny dot (it looks like someone put the point of a highlighter on the very tip of the arm). Their vision is not like ours and is more like dark and light (sun’s out - sun’s not out).

To get around, the sea star uses its arms with hundreds of little, tiny tube feet on each arm. None of the arms are dominant. Our Forbes Sea Stars have 5 arms each and have been clocked at a whopping five inches a minute! That is a sea star run! Full speed, petal to the metal, run! (That’s .005 mph.) When you don’t have to run down your food and most things don’t want to eat you or will only take a bite that you will grow back, speed is not a major concern. Their favorite food is most bivalves (animals with 2 shells) like oysters, mussels, and clams. The creatures that they are most concerned about avoiding are crabs, bottom dwelling fish, sea gulls, sea urchins, lobsters and (be surprised) humans.

To eat, the sea star wraps its arms with tube feet around a bivalve. The bivalve slams shut; it doesn’t want to get eaten. After roughly 10 hours the amount of pressure the sea star exerts on the bivalve forces it open, just a little bit. Then the sea star takes its stomach out through its mouth and begins to eat the squishy inside of the bivalve. When the sea star finally removes itself from the bivalve all that is left is shell (licked clean!). Mussels are easily the favorite food of the sea stars in our tank. I am not sure if it’s because they are easier to open or if it’s the fact that they prefer the taste. Our sea stars go through about a pound of mussels in a week. With some of the larger clams in the tank, our sea stars appear to attack them in a group, which amazes me since they have no brain. So I wonder - can they organize? Is it instinct? Communication beyond our understanding? We may never know.

Mysteries of the ocean are being unfolded every day. Remember we know more about the planet Venus than we do about our own oceans. Till the next “Meet the Tank”, take care.

Question of the Week

Fall foliage season is here! According to the Virginia Department of Forestry, the trees producing this beautiful display are:

• Ash - yellow, maroon leaves
• Beech - yellow to orange leaves
• Dogwood - scarlet to purple leaves
• Hickory - golden bronze leaves
• Oak - red, brown or russet leaves
• Poplar - golden yellow leaves
• Red maple - brilliant scarlet leaves

Leaf color is nearing its peak this week in the higher elevations of southwest Virginia and along the Blue Ridge Parkway. The Shenandoah Valley is at about 50% peak and the Piedmont is at about 25% peak. The Coastal Plain will peak around mid-November.

How do you think officials predict the dates of peak fall color?
     a. cool temperatures at night
     b. freezing temperatures at night
     c. shorter days, longer nights
     d. soil moisture
     e. leaf spotters

Answer:  Believe it or not, fall foliage predictions are made by leaf spotters - park rangers, foresters, lodging and restaurant operators, chamber of commerce officials, etc. “If we’re driving somewhere, we’re looking,” says one official. Leaf spotters send fall foliage reports to the state tourism division or visitor's bureau who then post it on a website. Many states also have a hotline and will provide text alerts.

In Virginia, go to the Virginia Department of Forestry website for the latest report on Virginia's fall foliage. If you want to avoid the crowds on Skyline Drive, the website also includes fall foliage driving tours.

http://www.dof.virginia.gov/fall/index.htm

Question of the Week

What are you afraid of?  Snakes, spiders, heights, loud noises?

For me, I am ok with snakes and spiders, although I am not fond enough of either to have one as a pet.

One animal that really creeps me out, though - crickets.  Perhaps I had one too many experiences with them as a child.  Growing up in a rural area surrounded by farms was wonderful - until fall when the field crickets invaded.  Generally, you can't see them but you can certainly hear them.  They can sing their little hearts out, especially in the middle of the night.  Sometimes it's so annoying that going after them is the only solution.  However, you can follow that infernal noise only so far.  They are incredibly adept at sensing when you are hot on the trail - instant silence.  Finding a silent cricket in the dark is very, very tricky.  But if you get lucky and manage to find the noisy  critter, then... Have you ever tried to kill a cricket?  They hop in 12 directions at once, and if you smush him - YUK!  Cricket guts go everywhere!

So, no, I am not fond of crickets.  You might say I have cricketaphobia.  Now what are you afraid of?

Finally, the rains came

Last week, the Richmond area received about five inches of rain, which helped to reduce the rainfall deficit in our area for the year. For the record, though, we’re still short by 4.9 inches of rainfall for the year.

During the weekend before remnants of Tropical Storm Nicole drenched the Richmond area, the county of Chesterfield had announced implementing mandatory water restrictions on September 28, 2010. For several weeks prior to the announcement of mandatory water restrictions, I witnessed homeowners with automatic sprinkling systems and golf courses in our area persistently irrigating their brown lawns as the water level in Lake Chesdin continually inched downwards to record low levels. Why do they do this?

To me, such behavior is not unlike that described in a 1968 journal article entitled “The Tragedy of the Commons” in the journal Science, December 13, 1968 by the late, renowned ecologist, Garrett Hardin. Using the concept of tragedy of the commons, we may view water as a common resource, which we pay very little for. Each of us wants to maximize the beauty of our lawns, our profits from golfers, etc. Each of us reasons that if I water a little extra to keep my lawn green, it won’t matter. We do this for our own self interest, without regard for the resource and end up doing harm to the common water supply and the rest of the water user groups as well. If all water users make this individual economic decision, then the water resource in common will be exhausted to the detriment to all.
So, in my infinite quest to do the ethically right thing and not harm others with my own actions, I used my truck to transport water in four 5-gallon plastic buckets from the James River to our home about two miles away to water our winter vegetable garden of Bloomsdale spinach, dwarf Siberian curly leaf kale, cilantro, and mustard greens. Fortunately for me, it started raining…I didn’t like adding additional CO2 into the atmosphere, and taking time away from family as I drove to and from the river.

As an aside, the availability of clean drinking water is at a crisis. About a year ago, the federal government predicted that within five years at least 36 states will experience water shortages as a result of climate change (rising temperatures and drought), population growth, urban sprawl and waste. Barry Nelson, senior policy analyst for the Natural Resources Defense Council (NRDC), summed up the change in philosophy that is upon us: “The last century was the century of water engineering. This century is going to have to be the century of water efficiency.”

Question of the Week

Suppose you are going on vacation and want to save on your heating bill.  Which will save more - turning off your heat completely (assuming your pipes won't freeze) or just setting the thermostat to a lower temperature?

In other words, does it cost more to heat the house up from a very cold temperature than it would to keep it at a more moderate temperature while you are gone?

Answer:  Turn off your heat! Based on years of research, the US Department of Energy concluded "the fuel required to reheat a building to a comfortable temperature is roughly equal to the fuel saved as the building drops to a lower temperature. You save fuel between the time that the temperature stabilizes at the lower level and the next time the heat is needed." In other words, during the period your house is at its coldest temperature, you are saving on your fuel bill. So if you aren't worried about your water pipes, pets or tender houseplants, turn off the heat while you are away. Not only will you save on your fuel bill, but you will also conserve valuable natural resources.

Scotch tape + 2 researchers = Nobel Prize

So… here’s a good one - two guys used Scotch tape and won a Nobel Prize. Hmmm…


Andre Geim and Konstantin Novoselov won the Nobel Prize in Physics on Tuesday for their pioneering work with a revolutionary new material called graphene. Basically a one-atom-thick layer of carbon, graphene could change the world as we know it.

Graphene is a flat single layer of carbon atoms arranged in a tight honeycomb pattern. It is stronger than steel and conducts electricity better than any other material. According to researchers at Columbia University, “It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap.”

So where does the tape come in? Graphene comes from graphite, good old fashioned pencil lead. At one atom thick, it is the thinnest of all materials. After its discovery in 2004, scientists were having trouble extracting a one-atom-thick layer. According to Novoselov, “The way you clean graphite is just cover it with tape and pull the tape off, and then throw it away. So once, I just picked it up out of the trash and we analyzed it.”

In all fairness, the contribution that won them the Nobel Prize was not the tape but their way of spotting the single layer of graphene in thicker flakes of graphite. A layer one atom thick is essentially invisible even with the most powerful microscope. The two researchers discovered that putting the graphene on a silicon wafer changes the color of the wafer, like the colors oil makes on water.

And why is this material so revolutionary? Graphene could replace silicon semi-conductors with smaller and faster chips. Since graphene performs well at room temperature, it might solve heat issues, as well. According to Michio Kaku at bigthink.com, other applications might include embedding the material in plastics so they conduct electricity, replacing carbon fibers in materials to make planes and satellites lighter, increasing efficiency of batteries with graphene powder, plus stiffer-stronger-lighter plastics, better touchscreens, and better sports equipment.

Graphene appears to be a supermaterial. Geim “would compare this situation with the one 100 years ago when people discovered polymers. It took some time before polymers went into use in plastics and became so important in our lives.” Revolutionary, indeed!

Photo courtesy of University of Manchester

Question of the Week

What are you afraid of? Ever wonder what makes us scream, shake, or shout when we get scared? Goose Bumps! The Science of Fear opens tomorrow at the Science Museum of Virginia!


So to celebrate, I will pose a question (or maybe 2):

What do women fear most?

What do men fear most?

Hint: The answer is a specific phobia, which is defined as an excessive fear of an object or situation.

Please post your guesses below in the Comment section. (Click on the blog title and then click "Post a Comment" or click on the word "comments" below).

(Answers will be posted next week.)

Answer:  Results differ slightly, depending on whose research you read, but generally, women are afraid of certain animals, like snakes and spiders, and men are afraid of heights, illness and being buried alive. Interesting, huh? And what are you afraid of?