biologyandfriends: December 2012

Wednesday, 12 December 2012

Squidddddd dissection!!

Last Friday my class was lucky enough to dissect some Cephalopoda (Head-foot) from the Mollusks phylum. Sadly I wasn't in attendance for this exciting new learning experience. I'm sad I missed out on this interactive hands on way of learning, as it always helps you grasp the material better, when you actually use it in real situations. However I know my classmates found it to be a phenomenal way of studying the information. Looking over the notes I saw that the class got to see some fascinating parts of the squid, like at one point they got to interact with the beak and see how it works. They also got to take a closer look at the internal organs of the squid helping them better understand their functions. Hopefully next time I will be able to participate in one of these hands on activities!

1.) The squid features 8 shorter arms and, 2 longer tentacles with suckers at the end.

some suckers

2.)The arms and tentacles serve two different purposes for the squid. The shorter arms are great for locomotion, because they are shorter than the tentacles, which grab prey and latch on to surfaces.

A close up of the sucker

4.)The suckers on the tentacles of a squid are a good predatory adaption as they easily grapple prey.

The beak

The squids beak is also good as it rips the prey apart making it easier for digestion.

5.) The soft bodied portion that contains the internal organs called the visceral mass
The also feature bilateral symmetry.

6.) A squid has two gills.

7.) The squids defensive ink sac empties into the water jet and it is a defense mechanism, it distracts the predator so it has time to escape.

8.) The pen provides the squid with support so it has shape making it capable of swimming. Without this vital body structure the squid would be a blob.

9.) I would assume that solid feces would exit through the anus.

Since I was absent I had to use other students photos

Wednesday, 5 December 2012

annelida dissection

Last week our Biology class did our very first dissection on an earthworm, or a lumbricus terrestris. It was a very interesting experience for my partner and I, both being petrified of worms had to tough it out. However some how we did manage to cut through all three of our worms, and scream while doing so. we began by slicing it on its ventral side. We then followed the steps and had to locate and identify different organs like the gizzard in the digestive tract. Overall it was a somewhat useful and scary learning experience that truly changed my attitude towards hands on work teaching me that it can't be taught only by book.

Questions!
1.)The pumping organ found within a earthworm can be called aortic arches or hearts. Also unlike us the worm has five of these pumping organs.

2.) When a worm munches on some soil, the soil would enter its mouth however the pharynx would pull in the food, then it would travel down the esophagus to the crop where it would then be moistened. The moist food would travel to the Gizzard and undergo mechanical digestion basically its ground up. After this the nutrients need to be absorbed the large intestine does this chemically. After this its ready to be excreted through the anus.

3.) Throughout our studies I actually learned that annelids feature well developed nervous systems. The brain its self is called the cerebral ganglion, using ganglia it connects to the ventral nerve cord with runs the worms entire body. A swollen area of nerves that entwines every segment to the brain is commonly known as ganglion they are found at each of the ventral cords segments.

4.) Out of the two organs in the worms excretory system I managed to catch glimpses of the Anus but not the nephridia as I ran out of time.

5.) Well it was simple to figure out the worms eating habits. As it seemed to leak soil every where when we accidently cut the intestine open.

6.) Sadly I didn't spot the setae on the worm which help it move around, by griping its surrounding environment.

7.) In certain worms the gizzard assists in this by churning and grinding the food down further.

8.) The excretory and digestive system are seen past segment 32.

9.)Worms mating can be confusing because the are hermaphrodites so they are able to produce male and female organs. Which is why they both collect sperm from one another and place it in sacs until they reach maturity. A sticky substance is then formed from the citicellium creating a ring with the fertilized eggs.