Lower Invertebrates
Phylum. |
Characteristics |
Body Plan |
Reproduction |
Digestion and Excretion |
Porifera |
-Sessile -No mouth or digestive cavity -Irregular shape -Filter feeders |
-Asymmetrical -2 germ layers -Acoelomate |
-Asexual (Budding, Gemmules) -Sexual (Hermaphrodites, Sperm released) |
-Filter feeders -H2o -Diffusion -Excurrent pore |
Cnidaria |
-Sessile -Free swimming -Stinger cells |
-Radial Symmetrical -2 germ layers -medusa/polyp |
-Asexual (polyp) -Budding -Sexual (medusa) -egg and sperm |
-1 opening for the mouth and anus -Diffusion |
Platyhelminthes |
-Free living or parasitic -body is flat -Mouth(pharynx) |
-Bilateral Symmetry -3 germ layers -Acelomates |
-Asexual (Fission regenerations) -Sexual (penis fencing) |
-Gastrovascular cavity -Mouth gets food(pharynx) -Flame cells |
Nematoda |
-More round in shape -Free living or parasitic -mouth and anus are separate |
-Bilateral symmetry -3 germ layers -Acoelomates |
-Sexual -Hermaphroditic |
-Separate mouth and anus -Diffusion and anus |
PARASITIC & FREE LIVING
Worms can be parasitic or free living. A free living worm can live freely. A parasitic worm needs a host to survive, the host acts as a provider. For example the host provides shelter, food and a perfect place to reproduce, without a host it would die. A free living worm has more organs and is more developed then a parastic worm. The parasitic worm has less organs because the host fills in the need for those extra organs.
Tapeworms
Tapeworms are segmented worms that live in a hosts intestines. Eating undercooked meat from infected animals is the main cause of tapeworm infection in people. It is also possible to contract pork tapeworms from foods prepared by an infected person. Because tapeworm eggs are passed with bowel movements, a person who doesn't wash hands well after wiping and then prepares food can contaminate the food. Tapeworms have a three-stage lifecycle, first stage is the egg stage, secondis an immature stage called a larva and thrid stage is the adult stage at which the worm can produce more eggs. Symptems depend on the type of tapeworm you get but some of the symptems you get are nausea, weakness, loss of appetite, abdominal pain, diarrhea and Weight loss and inadequate absorption of nutrients from food.