What is the taxonomic system ?
A universal system which organises organisms into taxa:
Domain, kingdom, Phylum, Class, Order, Family, Genus, Species
What are the 3 domains ?
Eukarya, Bacteria, Archaea
What are the kingdoms ?
Prostista, Prokarya, fungi, plants and animals.
What is convergent evolution ?
When different species independently develop similar anatomy due to similar environments.
What is an animal ?
Multicellular, heterotrophic, mobile, polorisation (have an anterior + posterior), epithelial cells, monophyletic - draw back to one common ancestor.
What are the basis for classification ?
Morphology, nucleic acids, biogeographic…
Describe the features of the porifera phylum
Sponges: No true organs or tissues. A hard body element called spinules (i.e their skeleton). Specialised feeding cells = choanocytes
Describe the features of the placozoan phylum
No mouth or gut are dipoblastic (have 2 tissue layers) and have contractile fibre cells for movement.
Describe the features of the ctenophore phylum
Cone jelly fish: Radial symmetry, diploblastic embroys (ectoderm +endoderm), Mesoglea extra cellular matrix, complete gut. 8 Ctenes (cones)
Describe the features of the cnidarian phylum
(Jelly fish, sea anemones, corals) Gastrovascular cavity (digestive + cardiac ) Nematocycts
What are nematocysts ?
Are a specialised organelle found on organisms in the cniderian phylum. They are long string like projections which are used to capture prey and act as a defence mechanism. It is formed by a tight coil which is released and penetrates the pray to release chemicals.
Describe the structure of bilaterian
Bilateral symmetry in embryo. Are tripoblastic- exoderm, endoderm and mesoderm. Are 2 major groups:
Protostomes = mouth develops first
Deuterostome = mouth develops second
Describe the features of the platyhelminths ?
Flat worms : Structurally diverse, may be free living or parasitic, Are unstructured and bilaterians
Describe the features of the annelid phylum
Segmented worm like bodies, separate ganglia (brain) for each. Thin permeable body for gas exchange. Lophotrochozoans ( feeding tube + free living laval stage)
Describe the features of the mollusks phylum
(Octopus, snails, squids) Lophorochozoans ( feeding tube + free living laval stage) Main organs in a visceral mass.
Describe the features of the nematode phylum
Roundworms- Ecdysozoan (3 layered cuticle which they shed as they grow). Thick, multi-layered cuticle (Gas exchange = gut), unsegmented - the contract body to move.
Describe the features of the arthropod phylum
Ecdysozoans with segmented bodies, Exoskeleton of chitin = waterproof. Muscles on the inside and jointed + special appendages.
Describe the features of the chordata phylum
- Dorsal hollow nerve cord - hollow tube which runs along the back above the notocord
- Tail that extends beyond the anus
- A dorsal support rod - notocord = the marker in embryos for where the spinal cord will be in the future.
Deuterostome
US
What are the differences between protostomes and deuterostomes ?
Protostomes develop their mouth first in their emryonic development. However, Deuterostomes develop their anus first.
