Notes - Porifera and Cnideria

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1 Notes - Porifera and Cnideria - Animals exist on every continent on the planet. Most people consider animals to be the most important kingdom as we are considered animals. But, what is an animal? What characteristics define an animal? - Animals are considered to be any,, without cell walls. Animals have developed a division of labour to better survive. That is, they have developed that take care of a particular function for the organism. Ex. - All organisms have some symmetry to their body plan. The more specialised tissues and organs an organism has the more likely it will move from to bilateral symmetry. - Also, as animals become more complex they tend to undergo cephalisation. is the gathering of nerve cells and into their anterior end ( ). A gathering of nerves is called a ganglion and in the case of large gathering this is called a. - All animals have 7 primary functions they carryout for survival. They are: 1.) the acquisition of nutrient. Often through a mouth that leads to a digestive gut. Feeding takes many forms like carnivorous, herbivorous, parasitic, filter feeders, and. 2.) Respiration 1

2 3.) Internal transport the movement of,, etc. to cells deep inside of the organism. This is often done by a. 4.) Excretion the expulsion of toxins ( ) and waste products ( ). 5.) Response 6.) Movement move throughout environment to gather nutrients,, and avoid. A skeletal system and muscles are needed in most cases. 7.) continue species by passing on. Can occur sexually or asexually. Phylum Porifera - Porifera this phylum includes both marine and fresh water sponges. Sponges are the only animals with no specialised systems like organs. Sponges have a simple body plan. They are essentially built like a sieve or. They function to pull water through 2

3 their millions of (small holes through their epidermal layer) into their central cavity, using tiny that beat back and forth. The flagellum are attached to special cells called collar cells, that are, and function to pull out of the water and engulf them for digestion. The water exits the sponge through the. The sponge maintains its structure through an internal skeleton made of spicules and/or. The spicules are created of calcium carbonate ( ), or silicon dioxide ( ) by the amebocyte cells. The flow of water serves as the respirator, excretory, and for the sponge. - Sponges reproduce both asexually and sexually. reproduction can occur through or budding. Gemmules occur during unfavourable conditions. The sponge will produce a small shaped collection of amebocytes surrounded by. This body is very resilient to cold temperatures and. It can grow into a sponge when conditions improve. Budding occurs when a piece is broken off and simply grows into another sponge. - Sexual reproduction occurs by sperm being released (male sponge) and carried out the osculum. If they reach a female sponge they will be taken up by the cells and delivered to the eggs. The zygote that develops into the larva, swims away to settle and grow into a new sponge. 3

4 Role in Nature - Sponges often form symbiotic relationships with photosynthetic bacteria in return for protection. Sponges help breakdown and release minerals from shells as well as filter water. Humans have used sponges for bathing since the ancient Romans as well as produce chemicals that are antibacterial. Phylum - Cnidaria are soft-bodied animals with stinging tentacles around their. This phylum includes jellyfish, anemones, and. All cnidaria have radial symmetry and specialised tissues. Most cnidaria have a 2 stage life cycle like many plants do. The cnidaria alternate between a polyp and a motile. - Both stages have a gastrovascular cavity for of food. They also both have a 3 layered body wall consisting of the epidermis,, and the. - Cnidarians feed by stinging their prey with nematocysts. Nematocysts are a specialised cell that functions like a. The nematocyst contains a small barb that is triggered by a specialised hair (when touched) and injects deadly toxin to stun their prey. Once stunned the prey is pushed into the cavity for digestion. Once digested the nutrients move into cells through. 4

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6 - No central nervous system or exists, but they do have a nerve net concentrated around the mouth. There are some cells in the epidermis for sensing touch, as well as the has very simple sense organs formed of and ocelli cells. - Waste removal occurs through as the cnidaria are only a few cells thick. - For the cnidaria uses specialised epidermal cells that can change shape when stimulated. This allows movement without. - Reproduction occurs sexually and asexually. occurs by budding or having entire medusa bud off. Sexual reproduction occurs when medusa release sperm/egg into the water which grows into a when fertilised. The zygote will become a larva, which can swim, and will move to a new area to settle,, and grow into a polyp. - There are three classes of cnidaria: Hydrozoa, Scyphozoan, and Anthozoa. - includes fresh water hydra and (not a true jellyfish as it is a colony of polyps working together). Most hydrozoa are 6

7 and have a very short medusa life stage. Most organisms have separate male and female but a few are (have both male and female reproductive organs). - Scyphozoa. This class functions oppositely in that the medusa is long lived and the polyp is very short in duration. - Anthosoa includes the anemones and. This class has NO medusa stage of life. Eggs and sperm are released from the polyp, develop into a ciliated larva that attaches and grows into another polyp. Anemones have a symbiotic relationship with many photosynthetic protists that live in their cells. As such they need to be near the light at the surface. Role in Nature - Many cnidarians have symbiotic relationships with, fish, and other small animals. The animals live amongst the tentacles for protection and feed scraps to the cnidaria in return. Coral reefs are an integral part of housing and protection for small sea creatures while also protecting coast lines from wave erosion. Jewelry and medicines are also very important uses for man. 7