This is a draft cheat sheet. It is a work in progress and is not finished yet.
Sponges are the Most Ancient Animals
- No true symmetry |
- No true tissue |
- Sessile =filter feeders...dont actually move |
- Have differentiated cells |
- Not tissue because cells don't work together doing just one function |
Individual Choanoflagellate = almost identical to the protists |
Some Features Common to Animals
Chemoorganoheterotrophs: all animals obtain energy and carbon by ingesting other organisms |
Multicellular: All animals are multicellular |
No cell walls: no animal cells contain cell walls |
Active Movement: Every sessile and sedentary animals possess active movement |
Embryonic Development: All animals have a developmental precursor (embryonic/larval...) stage |
Tissues: all animals except sponges have differentiated tissues |
Sexual Reproduction: most animals reproduce sexually |
Cambrian Explosion
Leading to the Cambrian Explosion |
Oxygen Levels
--> Slowly accumulating in atmosphere |
Predator/prey interactions
--> Force for evolution. Force for change
--> Only those with certain traits survive |
Changes in expression of Master regulator genes that control the body plan of an embryo during development |
Hox Genes
--> Transcription Factors
--> When expressed, they will lead to the expression of tons of other genes
----> Lead to things like limbs |
Variation in Body-Plan |
1. Bilateral Symmetry |
2. 3-tissue layers |
3. Body Cavity |
Also, first predator/prey adaptations arose; caused an influx in evolution |
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Animals Evolved 700mya
Unique parts of molecules to animals = chemical evidence 700mya |
First animal fossils 560mya |
1st Animal: Porifera (sponges)
--No true tissues |
Metazoa |
2nd Animals: Cnidarians |
Eumetazoa |
Specialized Tissue and Radial Symmetry Evolved
CNIDARIANS
Jellyfish |
2 Layers of Tissue
1. Ectoderm
2. Endoderm |
- Have muscle and nervous tissue |
- Endoderm: Gastrovascular cavity, No circulatory System |
- Not a dense pack of cells |
- Nidano cists --> Stinging Cells |
- Some are sessile
---> Usual just floating, not moving towards anything |
- Symmetry evolved (radial symmetry) |
Body Plan - Bilateral Symmetry
Bilaterally symmetric organisms have left and right sides that are superficially mirror images of each other |
Evolution of the anterior end (head end)...Not same as bottom (feet)
--> advantage for predator because you can just go get it |
Three Germ Layers |
Tissues are groups of cells that are similar and function |
Increased complexity
--> during embryonic development |
Ectoderm |
- Outside of embryo
- Sin and nervous system
- Outer Brain
- Cornea and lens of eye
- Sensory receptors |
Mesoderm |
- Skeletal System
- Muscular System
- Excretory System
- Organs
- Reproductive system (except germ cells)
- Lining of Body Cavity |
Endoderm |
- Epithelial lining of digestive tract
- Liver
- Epithelial lining of respiratory system
- Glands |
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Arthropods-Most Successful Animal Group
Most Successful |
- Most number of animals |
- Most diverse body please |
- Jointed exoskeleton (armor can move |
- Jointed appendages |
Examples of Arthropods |
- Mosquito
- Dragonfly
- Scorpion
- Lobster
- Shrimp |
Others |
- most animals have the same body parts, just in different numbers, slightly different locations, and of different sizes |
Just different number of building blocks --> master regulator genes trigger number of blocks per part |
- The key to different body types is changing where,if, and when master regulator genes are expressed in the embryo |
HOX GENES |
The changing of number of hox genes can be done in a lab. |
Body Plan - Body Cavity
Acoelomates |
- The beginning of cephalization |
- 3 layers of solid tissue and a digestive tube |
- Nervous system is starting |
Biletartians Increase Cephalization Levels |
Radial= no cephalization
--> Equal distribution of nervous system |
Increase of Cephalization
--> Concentrations of nervous system to head |
Pseudpcoelomates |
- Pseudo because no mesodurm on outside and inside
--> Body cavity is present for waste removal |
- Increase in flexability and movement |
- Hydrostatic Skeleton |
Coelomates |
The coelom is lined on both sides by mesoderm derived tissue |
- Allow organs to be independent of outside body
--> like the folds and movement of the intestines seperate from the skin |
- Also have Segmentation (like worms)
--> vertebre, 6 pack... |
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