Wednesday, July 25, 2012

Let's Bee Friends

Here at the Museum, we have an exhibit beehive where the honey bees (Apis mellifera) are free to come and go as they please since the hive entrance is connected by a tube to a hole in a glass window.  When you look at the hive, you're seeing mostly worker bees, which are all females.  Honey bees are famous, of course, for producing honey--but, did you know that about one third of our food crops, including almonds, apples and soybeans to name a few, are pollinated by honeybees?:
Bees, along with ants and wasps, belong to the order Hymenoptera which means "membranous wings."  There are about 18,000 hymenopteran species in North America, with about 115,000 species worldwide.  All have a very similar body structure.  As insects, they have three body parts (head, thorax, abdomen) and six legs and two antennae that are bent (sort of like your elbow bends.)  They also have two compound eyes and a cluster of three "simple eyes" or "ocelli" (on its forehead between the compound eyes) that function as light sensors.  Look closely in the photo below--can you see the three ocelli?:
Hymenopterans have a pair of forewings and a pair of hind wings.  And, most have chewing mouth parts, but in the case of bees, their mouths are modified to include a proboscis--think of it as a built-in soda straw!--that's used to suck up nectar.  Can you see the proboscis of this bumblebee?:
Honey is basically processed and condensed nectar.  When nectar is sucked up by a bee, it goes into a special "honey stomach" with enzymes to break down the nectar's sugar.  Once back at the hive, the nectar is transferred into cells where worker bees fan the cells with their wings to reduce the moisture (water) content, thus producing honey.  Bees also collect pollen, which is carried in "pollen baskets"--actually a special area on their hind legs which have a fringe of spiky hairs that the pollen sticks to.  Pollen is mixed with nectar to form "beebread," a food that is fed to developing bee larvae.  Check out the pollen basket on this bumblebee:
Not all bees are social.  Carpenter bees are solitary, with usually one female that makes a nest by boring a hole into wood--usually in trees, but also in man-made wooden objects.  In the photo below, this perfectly "drilled" hole in a fence rail on our Outdoor Trail was made by a female carpenter bee:
After she makes the nest, a female carpenter bee's job is to take care of the young.  The male carpenter bee mates with the female and then guards their territory.  Male carpenter bees may display fierce territorial behavior--even flying straight towards your face, but its all show and no sting--males don't have stingers (females do, though!)  You can tell this is a male carpenter bee because he has a white or cream colored spot on his head between his mouthparts:
 
By the way, an easy way to tell the difference between a carpenter bee and a bumble bee is to look at their abdomens--a carpenter bee has a black, shiny, relatively smooth abdomen, like in the photo above.  A bumblebee has a "fuzzy" abdomen with yellow stripes on the abdomen like in the photo below.  Also, all bumblebees will have a black face (no light colored dots on the males):
One final comment--you may have heard about something called "Colony Collapse Disorder" first reported about a decade ago.  In 2006, North American beekeepers reported losing 30%-90% of their bee colonies--bees seemed to die off or else never came back to their hives.  Although scientists aren't exactly sure what causes CCD, there's evidence to support the idea it could be a "perfect storm" of events with many contributing factors including poisoning by a class of pesticides called neonicotinoids (introduced in the 1990's to protect food crops from insect pests), infections caused by a virus (Israeli acute paralysis virus or IAPV), infestations of parasitic mites, and fungal infections.

So what can you do to help?  Try making your yard "bee friendlier" by using less pesticides, or by planting native plants that will help sustain bees with nectar and pollen.  I know a lot of people are extremely allergic to bee stings (including myself!) and many people are afraid of bees because of this.  But, in the grand scheme of nature, bees are very important to the ecosystem and essential for the pollination of many food crops, so I hope we can "bee" appreciative of this small natural wonder.  More "off the beaten path" in two weeks...
Cheers,
Lisa




Wednesday, July 11, 2012

A Closer Look at a "Living Fossil"

If you've read my previous blogs, you know I'm fascinated with "close-up" photography--I love the small details of nature!  So, can you guess what animal this is?  Its species is considered a "living fossil" and it's on display at our ever-popular Touch Tank.  Here's one of its compound eyes--similar to an insect's eye:
In addition to two compound eyes, it has various "eyes" that help sense different types of light--but they don't see images like our eyeballs!  In the photo below, can you spot a triangle of dots?  Located on the top part of the animal between the compound eyes, the center one is called the "endoparietal eye" and the two on either side of it are the "median eyes"--all play a role in sensing ultraviolet light:
From fossil evidence, we know this kind of animal has been around for about 360 million years.  Today, there are only 4 species worldwide.  The species we have in our Touch Tank, Limulus polyphemus, is found on the eastern coast of North and Central America--the other three species live in the Indo-Pacific region.  Since they are marine animals, they have gills to get oxygen from the water.  A closer look at the gills:
Under the top hard parts, there are thin flat parts like pages of a book--that's why they're sometimes called "book gills."   Not only do the gills help the animal breathe, they help it swim by flapping up and down.  By the way, this animal swims upside down in the water!  Here's what the gills look like when they're closed:
This animal has the word "crab" in its common name, but it's more closely related to today's spiders as well as extinct trilobites rather than crabs or other crustaceans.  In fact, this animal is classified in its very own class, "Merostomata," which means "legs attached to the mouth."  You can see why in this photo--see the bristly mouth and some of its legs?:
There are a total of 10 walking legs and at the end of each leg is a claw.  The claws help move food to its mouth--it eats stuff like worms and molluscs.  If the crab's first pair of claws have a rounded "boxing glove" shape, the crab is a boy, like in the photo below.  (A girl's first pair of claws would look like the two claws on the right in the photo below):
This animal has a tail--don't worry, no stinger!--that helps it steer while swimming and helps flip itself over (remember--it swims upside down!)  The second photo shows the tail where it joins to the body.  Technically the tail is called a "telson":
The two main body parts (cephalothorax and abdomen) have sort of a "hinge" that allows the animal to flex its body:
Here's the side view of both main body parts:
Have you figured out what it is?....Yep, a horseshoe crab!:
If you want to know more about horseshoe crabs, there are two websites I recommend.  The first is "The Horseshoe Crab" run by the Delaware-based Ecological Research & Development Group, a non-profit organization dedicated to horseshoe crab conservation.  It has a detailed description of horseshoe crab anatomy and an explanation of how LAL (Limulus amebocyte lysate) a derivative of horseshoe crab blood is used to test drugs, vaccines and medical products for bacterial toxins thereby saving human lives.  The Maryland Department of Natural Resources has an excellent overview of the life history of horseshoe crabs.

Many thanks to Touch Tank volunteers Dawson Connell, Tatum Conner, Carly Cook, Erin Copsey, Poppy Crawshaw, Megan Holley and Kristen Penrose who helped me with all these photos--very patient folks!  More off the beaten path in two weeks....
Cheers,
Lisa