Exoskeleton

An exoskeleton refers to the chitinous or calcified external skeleton used by numerous animal taxa for structural support and defense against predators.

Exoskeletons can be contrasted with endoskeletons (internal skeletons) that humans and other vertebrates have.

In the animal world, exoskeletons are much more common than endoskeletons -- millions of species have exoskeletons, while only a few thousand have endoskeletons.

Exoskeletons are especially popular among arthropods and mollusks, two of the largest animal phyla in existence.

Check for a few common examples of exoskeleton !

Bio Tutorial Class

Learning Bio in the evening definitely is awful...if it is not properly planned..sometimes it needs a lot of observation of students response, to come up with some ways to get their attention..

And when Arifah and I handled the group for a tutorial in the evening, we decided on the 'brainstorming' of the environmental issues that they should master for their SPM chapters..

It was all about : Global warming, greenhouse effect, deforestation, acidic rain, thinning of ozone layer, eutrophication, all kind of pollution...
It took 20 minutes for the group discussion...and the brainstorming of ideas..





Next 20 minutes were for the presentation...We did not have difficulties in getting the presenter~ many were willing to come forward !


while the rest were listening...




...Time passed unnoticed..Infact, we did not have enough time for the presentation!

Skeletal System

Locomotion and Support is the second Chapter of Bio Form 5..And we have just started it early of the week...,There are many teaching aids available for this chapter. It really helps the students to visualise the real bones better.

And I'm using the module, a compilation of notes..

...using the vertebra models, it helps the girls to identify the C1~ cervical 1 which is an atlas and cervical 2 which is an axis...Looking at the way the two vertebrae articulated...

The specieal feature that an axis has ~ an odontoid process..




Observing the intervertebral disc which is made up of cartilage...act as a cushion~ to absorb shock..
And we have three sets of big skeleton in our lab, for the girls to identify the bones...
..plus a set of a small skeleton...which is quite handy for me to carry around when I wanna explain the system !
...and we have the 'Vertebral column' model ..to identify the cervical, the thoracic, the lumbars, sacrum, coccyx..
Also we have six boxes of vertebral column models...enough for all girls to identify the types of vertebrae..

And of course the big chart, hung at the corner of the lab...
plus the 'X-Rays' of the rib bones....
All of the above teaching aids should be more than enough for the girls to master this chapter...

Introduction of the Vertebral Column

The vertebral column (also called the backbone, spine, or spinal column) consists of a series of 33 irregularly shaped bones, called vertebrae. These 33 bones are divided into five categories depending on where they are located in the backbone.

The first seven vertebrae are called the cervical vertebrae. Located at the top of the spinal column, these bones form a flexible framework for the neck and support the head. The first cervical vertebrae is called the atlas and the second is called the axis. The atlas' shape allows the head to nod "yes" and the axis' shape allows the head to shake "no".

The next twelve vertebrae are called the thoracic vertebrae. These bones move with the ribs to form the rear anchor of the rib cage. Thoracic vertebrae are larger than cervical vertebrae and increase in size from top to bottom.

After the thoracic vertebrae, come the lumbar vertebrae. These five bones are the largest vertebrae in the spinal column. These vertebrae support most of the body's weight and are attached to many of the back muscles.

The sacrum is a triangular bone located just below the lumbar vertebrae. It consists of four or five sacral vertebrae in a child, which become fused into a single bone after age 26. The sacrum forms the back wall of the pelvic girdle and moves with it.

The bottom of the spinal column is called the coccyx or tailbone. It consists of 3-5 bones that are fused together in an adult. Many muscles connect to the coccyx.

Annelida - Locomoção

Hydrostatic skeleton

A hydrostatic skeleton or hydroskeleton is a structure found in many cold-blooded organisms

and soft-bodied animals consisting of a fluid-filled cavity, the coelom, surrounded by muscles.

The pressure of the fluid and action of the surrounding muscles are used to change an organism's shape and produce movement, such as burrowing or swimming.

Some examples are soft bodied animals such as sea anemones and earthworms.

Hydrostatic skeletons have a role in the locomotion of echinoderms (starfish, sea urchins), cnidarians(jellyfish),annelids (earthworms), nematodes, and other invertebrates.

Sea anemones
caterpillar
leech
earthworm
jelly fish
sea cucumber.

- Hydrostatic skeletons consist of fluid-filled closed chambers.

- Internal pressures generated by muscle contractions cause

i. movement as well as

ii. maintain the shape of the animals, such as the sea anemone and worms.

The sea anemone has one set of longitudinal muscles in the outer layer of the body, and a layer of circular muscles in the inner layer of the body. The anemone can elongate or contract its body by contracting one or the other set of muscles.

Extracted. TQ

Learn Bio Via gempurbio blog

It is surely interesting...once a month, bring your students to learn Bio in a different approach or style....by using ICT.....and it is gempurbio.blogspot.com. My pet project .

..And that was what I did ...again with my form 5 Helpilia girls. I follow this class from form 4...and now they are in Form 5... they are my pet students I supposed !..

And the lesson took place for two periods...They accessed my posts on Chapter Transport~ The chapter which they have just completed ..It is supposed to be a revision...and they were required to ask questions via Formspring...and they asked many questions....and I was trying to answer as many as I managed in a limited given time.

It was so fast...they wished to stay longer in the Lab Comp....