Saturday, September 15, 2012

The Tiniest Bits of Life

Science is one of those subjects that even after teaching it for years, I still get amazed! Being an open minded homeschooler is one of those things that allows me to see each amazing new bit of information as transforming. I get so excited - I hope that I share that excitement with my children!

Today I thought I'd share some thoughts about the tiniest units of life. The one celled organisms that make up all living things in the universe. Cells are the workhorses that keep things alive. God has created the cell to be an amazing miniature structure that carries out the function of getting things done for the greater organism.

Every cell has three parts.
1) the cell membrane - which surrounds the cell and protects it. Everything that leaves the cell including its waste must pass through this membrane. It is like a wall protecting a city.
2) the inside of the cell is called the cytoplasm. Small organs move around and do their work within this cytoplasm. These organs are called organelles.
3) The nucleus of the cell is usually found in the center. It is the brain of the cell and directs the work that happens within the cell. Within the nucleus are the chromosomes which determine exactly what function the cell holds. They also determine what the greater organism will be.

Saturday, September 1, 2012

Living Stars and other Awesome Creatures

We love looking for starfish when we go to the ocean... They are an amazing creature and I am so puzzled at how they manage to survive. Let's take a closer look...

1) The sea star is beautiful and looks more like art than an animal. Yet, when it is dinner time this art comes alive. It will grasp a clam with its rays (arms) and will pull the shell apart and stick its tongue like stomach into the clam and begin to eat it.
2)Sea urchins are a relative of the sea star, but they look more like a porcupine. The sea urchin is usually a spiny creature resembling a ball... but the sand dollar is also a sea urchin with very small spines that look more like fur. Another interesting sea urchin is the sea cucumber... looks just like a cucumber stuck on the bottom of the ocean!
3) The sponge -These creatures look more like stones than living things. The sponge has pores that allow water to pass through and then an opening in the top where water flows out. Tiny food particles are absorbed during the movement of the water, and this is how the sponge stays alive. Sponges have also been harvested for use in our lives for scrubbing and bathing.
4)The hydra is a tiny fresh - water invertebrate with tentacles around its mouth. It is similar to the sea anemone, and can move by doing a somersault with its tentacles.
5) Jellyfish are amazing creatures. They have stinging cells located on the membranes of their tentacles. The jellyfish life cycle is amazing. It begins as a polyp dropped by a jellyfish adult. The polyp attaches to an object on the ocean floor, and then begins to grow and look like a coral polyp. As this polyp matures it will divide into stacked disk like sections. Each of these will break away and form a young "medusa." A medusa is the free floating umbrella shaped stage. It stays with plankton and grows to look like an adult jellyfish and is then large enough to swim by itself and leave.