Cnidaria video notes

1. Cnidaria = the phylum of sea anemones and jellyfish.

2. ‘they were the first to have nerves, they invented cabling, that’s what nerves are’

3. Early scientist thought they were plants, but they do not do photosynthesis. They eat plankton or fish.

4. Trombley discovered that they could move on their own and eat daphnia (plankton). He was the first to realize that they were in fact animals.

5. Cnidarians evolved from sponges (Porifera – the first animal)

6. Sea star’s eat anemones (stimulus is touch) and you can detect the action potentials with an oscilloscope.

7. Nerves fire their action potential signal based on an ‘all or none principle’, this means that the amplitudes are always the same, but the frequency changes to indicate a more intense sensation.

8. There is a minimum amount of time that has to be in between the action potentials. This is called the refractory period.