Wednesday, September 19, 2012

Polyphemus Caterpillar & Cocoon

Many, many thanks to Maggie McCartney and Thomas Waser in our Herpetology Department for spotting this incredible caterpillar on our Museum grounds!  It's a polyphemus caterpillar--my index finger is shown for scale.  And, yes, the caterpillar really is almost a neon green color.  I took these photos on September 15, 2012.
I usually take my camera with me everywhere I go since I never know when a great photo opportunity will turn up.  And wouldn't you know it--this was one of those rare days I didn't bring my camera with me!  Fortunately, I was able to put the caterpillar in my empty lunchbox and took it home with me.  At home, I immediately started photographing to take advantage of the day's remaining sunlight--it was the only way to do justice to the brilliant green color!  This side view shows the caterpillar walking along a stick:
The first three pairs of legs closest to the head are the "true legs" or thoracic legs.  The more fleshy looking legs are "prolegs"--the middle four pair are the anterior prolegs and the last pair are the anal prolegs.  The next photo shows the contrast between the thoracic legs and prolegs:
Here'a an even closer look at the prolegs.  You can see that each proleg ends in a flat pad rimmed with small hooks called "crochets":
It was fascinating to watch the superbly choreographed movements of all the legs--it made the body seem to undulate or ripple:
 
Here's a close-up of the head with the mouth parts closed.  The two slender finger-like projections to the side of the mouth are the antennae:
Here's the mouth open--kinda scary, right?:
Do you see a small cluster of five dark dots on the side of the head?  These are simple eyes called "stemmata."  There's a sixth simple eye positioned close to the base of the antenna, making a total of 12 simple eyes on the caterpillar's head:
Some characteristic markings of the polyphemus caterpillar are the bright slanting yellow lines along most of the middle segments, punctuated by silver and reddish "warts."  You can also see some very fine hairs:
After I finished with the above photos, I put the caterpillar in a small container with some paper towels on the bottom.  I figured I'd download the photos first to see if they turned out clearly before releasing the caterpillar in my backyard.  To my surprise, an hour later, I found the caterpillar beginning to make its cocoon!  In the next photo you see the back end of the caterpillar--the dark lines form the anal plate.  At this point, its body was already stuck to the paper towel:
In the next shot, look carefully and you can see some silk strands.  These strands are usually used to help anchor the caterpillar into a leaf.  It will draw the sides of a leaf together and then spin its cocoon.  In this case, it used what was on hand--the paper towels!  I trimmed the edges of the paper towel to give it a more leaf-like shape, and when I checked on it later in the evening, it had finished its cocoon:
So now what?  If I'm lucky, perhaps by May of next year it'll emerge as a beautiful poyphemus moth.  If it survives, I'll post the photos.  For now, in order to help regulate natural temperature, the cocoon is sitting in a large container in my garage, waiting  for spring....

And, it seems my cocoon wasn't the only one found on the Museum grounds!  Horticulture staff member Darl Fletcher and educator Judy Molnar pointed out yet another polyphemus caterpillar making a cocoon--this one in the leaves of a tropical milkweed plant located in our horticulture support area.  I was able to get a shot of the face, with the bright yellow line on the first thoracic segment, and also a detail of those lovely silvery "warts" and finally a look at the caterpillar as it began to draw leaves around itself to make the cocoon--do you see the fine silk strands?:
Finally, here's what its cocoon looks like a day later:
More "off the beaten path" in two weeks....
Cheers,
Lisa




Wednesday, September 5, 2012

More "Whose Feet?"

The topic today is feet....so here's the first set of feet.  Can you guess what they belong to?
What about this one?  Hint:  It's the hind foot of an animal that spends a lot of time in the water, but can also come out onto land:
This next one is an odd sort of "foot" belonging to a marine snail:
The last photo shows an animal that has lots and lots of tiny "tube feet" that are like little suction cups:
Have it all figured out?  The first set of feet--with the nice talons!--belongs to a black vulture.  We have the black vulture and a turkey vulture on our Outdoor Trail:
In the second photo, the hind foot belongs to a newt--a type of salamander:
The third photo shows the underside of a knobbed whelk--a marine mollusc, and specifically, a "gastropod" which means "stomach foot."  The bottom part, which is soft and slimy, is the "foot."  When the animal is threatened, it can pull its "foot" into it's hard shell, and close a hard bit of shell (the "operculum") over the shell opening to protect itself from predators.  Think of it as a built-in "trapdoor."  The next photo shows the "foot" starting to move into the shell, and the photo after that shows the operculum:
The tiny "tube feet" belong to a seastar--or "starfish" if you prefer.  Seastars eat clams and use their tube feet to pry apart the clam.  The seastar can then evert it's stomach into the clam shell, digest the clam and pull it's stomach back in.  In the top photo below, you can see the "suction cup" action of the tube feet--the seastar is sticking to the glass side of it's aquarium.  In the bottom photo below, you see the seastar beginning to engulf a clam :
In the last photo, you see the underside of the seastar--notice its radial symmetry.  In the center of its body is its mouth opening:
Hope you enjoyed looking at these feet.  More "off the beaten path" in two weeks!
Cheers,
Lisa